Timothy syndrome: Difference between revisions

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__NOTOC__
__NOTOC__
{{SI}}
{{CMG}}; {{AE}} {{VKG}}
{{CMG}}; {{AE}} {{VKG}}


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==Overview==
==Overview==
Timothy syndrome is a rare syndrome that follows [[autosomal dominant]] inheritance pattern. Timothy syndrome is a multisystem disorder characterized by [[physiological]] and developmental defects which include long [[LQTS|QT-prolongation]], [[arrhythmia]]s, structural [[heart defects]], [[syndactyly]] and [[autism]] spectrum disorders. Timothy syndrome may be classified into 2 groups, classical form(type-1) and atypical form(type-2). Timothy syndrome caused by [[mutations]] in [[CACNA1C]], which encodes for [[calcium channel]] α subunit. Timothy syndrome often ends in early death. The United States of America in order to categorize a [[condition]] as a [[rare disease]] it should affect fewer than 200,000 people. [[Rare diseases]] also called as [[Orphan disease|orphan diseases]]. [[Orphan Drug Act]] was passed in 1983 by congress for the [[rare diseases]]. Today an average of 25-30 million Americans have been reported with [[rare diseases]]. The number of people with individual [[rare disease]] may be less but overall the number of people with [[rare diseases]] are large in number.
Timothy syndrome is a rare syndrome that follows [[autosomal dominant]] inheritance pattern. Timothy syndrome is a multisystem disorder characterized by [[physiological]] and developmental defects which include long [[LQTS|QT-prolongation]], [[arrhythmia]]s, structural [[heart defects]], [[syndactyly]] and [[autism]] [[spectrum]] disorders. Timothy syndrome may be classified into 2 groups, classical form(type-1) and atypical form(type-2). Timothy syndrome caused by [[mutations]] in [[CACNA1C]], which encodes for [[calcium channel]] α subunit. Timothy syndrome often ends in early death. The United States of America in order to categorize a [[condition]] as a [[rare disease]] it should affect fewer than 200,000 people. [[Rare diseases]] also called as [[Orphan disease|orphan diseases]]. [[Orphan Drug Act]] was passed in 1983 by congress for the [[rare diseases]]. Today an average of 25-30 million Americans have been reported with [[rare diseases]]. The number of people with individual [[rare disease]] may be less but overall the number of people with [[rare diseases]] are large in number.


==Historical Perspective==
==Historical Perspective==
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* Timothy syndrome was first discovered by Reichenbach and Marks, in 1992.<ref name="pmid1318983">{{cite journal| author=Reichenbach H, Meister EM, Theile H| title=[The heart-hand syndrome. A new variant of disorders of heart conduction and syndactylia including osseous changes in hands and feet]. | journal=Kinderarztl Prax | year= 1992 | volume= 60 | issue= 2 | pages= 54-6 | pmid=1318983 | doi= | pmc= | url=https://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&tool=sumsearch.org/cite&retmode=ref&cmd=prlinks&id=1318983  }}</ref><ref name="pmid7572644">{{cite journal| author=Marks ML, Trippel DL, Keating MT| title=Long QT syndrome associated with syndactyly identified in females. | journal=Am J Cardiol | year= 1995 | volume= 76 | issue= 10 | pages= 744-5 | pmid=7572644 | doi=10.1016/s0002-9149(99)80216-1 | pmc= | url=https://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&tool=sumsearch.org/cite&retmode=ref&cmd=prlinks&id=7572644  }}</ref>
* Timothy syndrome was first discovered by Reichenbach and Marks, in 1992.<ref name="pmid1318983">{{cite journal| author=Reichenbach H, Meister EM, Theile H| title=[The heart-hand syndrome. A new variant of disorders of heart conduction and syndactylia including osseous changes in hands and feet]. | journal=Kinderarztl Prax | year= 1992 | volume= 60 | issue= 2 | pages= 54-6 | pmid=1318983 | doi= | pmc= | url=https://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&tool=sumsearch.org/cite&retmode=ref&cmd=prlinks&id=1318983  }}</ref><ref name="pmid7572644">{{cite journal| author=Marks ML, Trippel DL, Keating MT| title=Long QT syndrome associated with syndactyly identified in females. | journal=Am J Cardiol | year= 1995 | volume= 76 | issue= 10 | pages= 744-5 | pmid=7572644 | doi=10.1016/s0002-9149(99)80216-1 | pmc= | url=https://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&tool=sumsearch.org/cite&retmode=ref&cmd=prlinks&id=7572644  }}</ref>


* In 1995, Splawski, Reichenbach, and Marks were the first to give the name Timothy syndrome in the honor of  Dr. Katherine W. Timothy who did the [[Phenotype|phenotypic]] analysis.<ref name="pmid221060443">{{cite journal| author=Gillis J, Burashnikov E, Antzelevitch C, Blaser S, Gross G, Turner L et al.| title=Long QT, syndactyly, joint contractures, stroke and novel CACNA1C mutation: expanding the spectrum of Timothy syndrome. | journal=Am J Med Genet A | year= 2012 | volume= 158A | issue= 1 | pages= 182-7 | pmid=22106044 | doi=10.1002/ajmg.a.34355 | pmc=3319791 | url=https://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&tool=sumsearch.org/cite&retmode=ref&cmd=prlinks&id=22106044  }}</ref>
* In 1995, Splawski, Reichenbach, and Marks were the first to give the name Timothy syndrome in the honor of  Dr.Katherine W. Timothy who did the [[Phenotype|phenotypic]] analysis.<ref name="pmid221060443">{{cite journal| author=Gillis J, Burashnikov E, Antzelevitch C, Blaser S, Gross G, Turner L et al.| title=Long QT, syndactyly, joint contractures, stroke and novel CACNA1C mutation: expanding the spectrum of Timothy syndrome. | journal=Am J Med Genet A | year= 2012 | volume= 158A | issue= 1 | pages= 182-7 | pmid=22106044 | doi=10.1002/ajmg.a.34355 | pmc=3319791 | url=https://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&tool=sumsearch.org/cite&retmode=ref&cmd=prlinks&id=22106044  }}</ref>


== Classification ==
== Classification ==
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{| class="wikitable"
{| class="wikitable"
|+
|+
|'''Type'''  
!'''Type'''
|'''Gene'''
!'''Gene'''
|'''Protein involved'''
!'''Protein involved'''
|'''Location'''
!'''Location'''
|'''Mutations'''
!'''Mutations'''
|'''Inheritance pattern'''
!'''Inheritance pattern'''
|'''Symptoms'''
!'''Symptoms'''
|-
|-
|Classic Timothy syndrome
!Classic Timothy syndrome
|[[CACNA1C]]
|[[CACNA1C]]
|[[Voltage-dependent calcium channel|Voltage]]-dependent [[L-type calcium channel]] subunit alpha-1C
|[[Voltage-dependent calcium channel|Voltage]]-dependent [[L-type calcium channel]] subunit alpha-1C
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|[[Long QT syndrome]] with [[syndactyly]]
|[[Long QT syndrome]] with [[syndactyly]]
|-
|-
|Atypical Timothy syndrome
!Atypical Timothy syndrome
|[[CACNA1C]]
|[[CACNA1C]]
|[[Voltage-gated calcium channels|Voltage]]-dependent [[L-type calcium channel]] subunit alpha-1C
|[[Voltage-gated calcium channels|Voltage]]-dependent [[L-type calcium channel]] subunit alpha-1C
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*It is understood that Timothy syndrome both classical and atypical form is the result of a [[missense mutation]] in the [[CACNA1C]] [[gene]].<ref name="pmid28371864">{{cite journal| author=Walsh MA, Turner C, Timothy KW, Seller N, Hares DL, James AF et al.| title=A multicentre study of patients with Timothy syndrome. | journal=Europace | year= 2018 | volume= 20 | issue= 2 | pages= 377-385 | pmid=28371864 | doi=10.1093/europace/euw433 | pmc= | url=https://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&tool=sumsearch.org/cite&retmode=ref&cmd=prlinks&id=28371864  }}</ref><ref name="pmid27868338">{{cite journal| author=Baurand A, Falcon-Eicher S, Laurent G, Villain E, Bonnet C, Thauvin-Robinet C et al.| title=Incomplete Timothy syndrome secondary to a mosaic mutation of the CACNA1C gene diagnosed using next-generation sequencing. | journal=Am J Med Genet A | year= 2017 | volume= 173 | issue= 2 | pages= 531-536 | pmid=27868338 | doi=10.1002/ajmg.a.38045 | pmc= | url=https://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&tool=sumsearch.org/cite&retmode=ref&cmd=prlinks&id=27868338  }}</ref><ref name="pmid21700933">{{cite journal| author=Cheng EP, Yuan C, Navedo MF, Dixon RE, Nieves-Cintrón M, Scott JD et al.| title=Restoration of normal L-type Ca2+ channel function during Timothy syndrome by ablation of an anchoring protein. | journal=Circ Res | year= 2011 | volume= 109 | issue= 3 | pages= 255-61 | pmid=21700933 | doi=10.1161/CIRCRESAHA.111.248252 | pmc=3151468 | url=https://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&tool=sumsearch.org/cite&retmode=ref&cmd=prlinks&id=21700933  }}</ref>
*It is understood that Timothy syndrome both classical and atypical form is the result of a [[missense mutation]] in the [[CACNA1C]] [[gene]].<ref name="pmid28371864">{{cite journal| author=Walsh MA, Turner C, Timothy KW, Seller N, Hares DL, James AF et al.| title=A multicentre study of patients with Timothy syndrome. | journal=Europace | year= 2018 | volume= 20 | issue= 2 | pages= 377-385 | pmid=28371864 | doi=10.1093/europace/euw433 | pmc= | url=https://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&tool=sumsearch.org/cite&retmode=ref&cmd=prlinks&id=28371864  }}</ref><ref name="pmid27868338">{{cite journal| author=Baurand A, Falcon-Eicher S, Laurent G, Villain E, Bonnet C, Thauvin-Robinet C et al.| title=Incomplete Timothy syndrome secondary to a mosaic mutation of the CACNA1C gene diagnosed using next-generation sequencing. | journal=Am J Med Genet A | year= 2017 | volume= 173 | issue= 2 | pages= 531-536 | pmid=27868338 | doi=10.1002/ajmg.a.38045 | pmc= | url=https://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&tool=sumsearch.org/cite&retmode=ref&cmd=prlinks&id=27868338  }}</ref><ref name="pmid21700933">{{cite journal| author=Cheng EP, Yuan C, Navedo MF, Dixon RE, Nieves-Cintrón M, Scott JD et al.| title=Restoration of normal L-type Ca2+ channel function during Timothy syndrome by ablation of an anchoring protein. | journal=Circ Res | year= 2011 | volume= 109 | issue= 3 | pages= 255-61 | pmid=21700933 | doi=10.1161/CIRCRESAHA.111.248252 | pmc=3151468 | url=https://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&tool=sumsearch.org/cite&retmode=ref&cmd=prlinks&id=21700933  }}</ref>
*[[CACNA1C]] [[gene]] encodes for [[calcium channel]] α [[subunit]] across [[cell membranes]].
*[[CACNA1C]] [[gene]] encodes for [[calcium channel]] α [[subunit]] across [[cell membranes]].
*Any [[missense mutation]] in exon 8 (atypical form) and exon 8a (classical form) of [[CACNA1C]] [[gene]] results in structural changes of Ca(V)1.2[[Ion channel|channels]] and delayed [[calcium channel]] α subunit closing and, thus, increased [[cellular]] excitability.<ref name="pmid15454078">{{cite journal| author=Splawski I, Timothy KW, Sharpe LM, Decher N, Kumar P, Bloise R et al.| title=Ca(V)1.2 calcium channel dysfunction causes a multisystem disorder including arrhythmia and autism. | journal=Cell | year= 2004 | volume= 119 | issue= 1 | pages= 19-31 | pmid=15454078 | doi=10.1016/j.cell.2004.09.011 | pmc= | url=https://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&tool=sumsearch.org/cite&retmode=ref&cmd=prlinks&id=15454078  }}</ref><ref name="pmid22999068">{{cite journal| author=Dixon RE, Cheng EP, Mercado JL, Santana LF| title=L-type Ca2+ channel function during Timothy syndrome. | journal=Trends Cardiovasc Med | year= 2012 | volume= 22 | issue= 3 | pages= 72-6 | pmid=22999068 | doi=10.1016/j.tcm.2012.06.015 | pmc=3640256 | url=https://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&tool=sumsearch.org/cite&retmode=ref&cmd=prlinks&id=22999068  }}</ref><ref name="pmid26822303">{{cite journal| author=Dick IE, Joshi-Mukherjee R, Yang W, Yue DT| title=Arrhythmogenesis in Timothy Syndrome is associated with defects in Ca(2+)-dependent inactivation. | journal=Nat Commun | year= 2016 | volume= 7 | issue=  | pages= 10370 | pmid=26822303 | doi=10.1038/ncomms10370 | pmc=4740114 | url=https://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&tool=sumsearch.org/cite&retmode=ref&cmd=prlinks&id=26822303  }}</ref>
*Any [[missense mutation]] in [[exon]] 8 (atypical form) and [[exon]] 8a (classical form) of [[CACNA1C]] [[gene]] results in structural changes of Ca(V)1.2[[Ion channel|channels]] and delayed [[calcium channel]] α subunit closing and, thus, increased [[cellular]] excitability.<ref name="pmid15454078">{{cite journal| author=Splawski I, Timothy KW, Sharpe LM, Decher N, Kumar P, Bloise R et al.| title=Ca(V)1.2 calcium channel dysfunction causes a multisystem disorder including arrhythmia and autism. | journal=Cell | year= 2004 | volume= 119 | issue= 1 | pages= 19-31 | pmid=15454078 | doi=10.1016/j.cell.2004.09.011 | pmc= | url=https://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&tool=sumsearch.org/cite&retmode=ref&cmd=prlinks&id=15454078  }}</ref><ref name="pmid22999068">{{cite journal| author=Dixon RE, Cheng EP, Mercado JL, Santana LF| title=L-type Ca2+ channel function during Timothy syndrome. | journal=Trends Cardiovasc Med | year= 2012 | volume= 22 | issue= 3 | pages= 72-6 | pmid=22999068 | doi=10.1016/j.tcm.2012.06.015 | pmc=3640256 | url=https://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&tool=sumsearch.org/cite&retmode=ref&cmd=prlinks&id=22999068  }}</ref><ref name="pmid26822303">{{cite journal| author=Dick IE, Joshi-Mukherjee R, Yang W, Yue DT| title=Arrhythmogenesis in Timothy Syndrome is associated with defects in Ca(2+)-dependent inactivation. | journal=Nat Commun | year= 2016 | volume= 7 | issue=  | pages= 10370 | pmid=26822303 | doi=10.1038/ncomms10370 | pmc=4740114 | url=https://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&tool=sumsearch.org/cite&retmode=ref&cmd=prlinks&id=26822303  }}</ref>
*There is one more mutation in ''G406R'' that is associated with the timothy syndrome.<ref name="pmid282119895">{{cite journal| author=Sepp R, Hategan L, Bácsi A, Cseklye J, Környei L, Borbás J et al.| title=Timothy syndrome 1 genotype without syndactyly and major extracardiac manifestations. | journal=Am J Med Genet A | year= 2017 | volume= 173 | issue= 3 | pages= 784-789 | pmid=28211989 | doi=10.1002/ajmg.a.38084 | pmc= | url=https://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&tool=sumsearch.org/cite&retmode=ref&cmd=prlinks&id=28211989  }}</ref><ref name="pmid1149428">{{cite journal| author=De Oliveira CC, Figueiredo EA, Gazzinelli G, Howells RE, Pellegrino J| title=Biochemical changes in the transformation of Schistosoma mansoni cercariae to schistosomules. | journal=Comp Biochem Physiol B | year= 1975 | volume= 51 | issue= 4 | pages= 417-20 | pmid=1149428 | doi=10.1016/0305-0491(75)90031-0 | pmc= | url=https://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&tool=sumsearch.org/cite&retmode=ref&cmd=prlinks&id=1149428  }}</ref>
*There is one more [[mutation]] in ''G406R'' that is associated with the timothy syndrome.<ref name="pmid282119895">{{cite journal| author=Sepp R, Hategan L, Bácsi A, Cseklye J, Környei L, Borbás J et al.| title=Timothy syndrome 1 genotype without syndactyly and major extracardiac manifestations. | journal=Am J Med Genet A | year= 2017 | volume= 173 | issue= 3 | pages= 784-789 | pmid=28211989 | doi=10.1002/ajmg.a.38084 | pmc= | url=https://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&tool=sumsearch.org/cite&retmode=ref&cmd=prlinks&id=28211989  }}</ref><ref name="pmid1149428">{{cite journal| author=De Oliveira CC, Figueiredo EA, Gazzinelli G, Howells RE, Pellegrino J| title=Biochemical changes in the transformation of Schistosoma mansoni cercariae to schistosomules. | journal=Comp Biochem Physiol B | year= 1975 | volume= 51 | issue= 4 | pages= 417-20 | pmid=1149428 | doi=10.1016/0305-0491(75)90031-0 | pmc= | url=https://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&tool=sumsearch.org/cite&retmode=ref&cmd=prlinks&id=1149428  }}</ref>
*The location of ''G406R'' is in domain one segment six (''D1S6'') which holds glycine at this position and plays a very important role in voltage-dependent inactivation  
*The location of ''G406R'' is in domain one segment six (''D1S6'') which holds [[glycine]] at this position and plays a very important role in [[voltage]]-dependent inactivation.
*[[Calcium channel]] α subunit especially Ca(V)1.2 involved in transporting positively charged [[calcium ions]] into the [[cells]] across a [[cell membrane]] which plays a critical role in the normal function of [[heart]] and [[brain]] cells
*[[Calcium channel]] α subunit especially [[Ca]](V)1.2 involved in transporting positively charged [[calcium ions]] into the [[cells]] across a [[cell membrane]] which plays a critical role in the normal function of [[heart]] and [[brain]] [[Cells (biology)|cells]].
*[[Mutation|Mutations]] in Ca(V)1.2 [[Calcium channel|calcium channels]] leads to disruption of the following events in the [[heart]] and other organs:<ref name="pmid259819772">{{cite journal| author=Betzenhauser MJ, Pitt GS, Antzelevitch C| title=Calcium Channel Mutations in Cardiac Arrhythmia Syndromes. | journal=Curr Mol Pharmacol | year= 2015 | volume= 8 | issue= 2 | pages= 133-42 | pmid=25981977 | doi=10.2174/1874467208666150518114857 | pmc=4762596 | url=https://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&tool=sumsearch.org/cite&retmode=ref&cmd=prlinks&id=25981977  }}</ref>
*[[Mutation|Mutations]] in Ca(V)1.2 [[Calcium channel|calcium channels]] leads to disruption of the following events in the [[heart]] and other organs:<ref name="pmid259819772">{{cite journal| author=Betzenhauser MJ, Pitt GS, Antzelevitch C| title=Calcium Channel Mutations in Cardiac Arrhythmia Syndromes. | journal=Curr Mol Pharmacol | year= 2015 | volume= 8 | issue= 2 | pages= 133-42 | pmid=25981977 | doi=10.2174/1874467208666150518114857 | pmc=4762596 | url=https://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&tool=sumsearch.org/cite&retmode=ref&cmd=prlinks&id=25981977  }}</ref>
**Cell-to-cell communication
**Cell-to-cell communication
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**Normal regulation of certain [[genes]]
**Normal regulation of certain [[genes]]


* Due to the fact that [[exon]] 8(atypical Timothy syndrome) is more expressed in heart muscles than that of exon 8a(classic Timothy syndrome) patients with exon 8 mutation have a severe form of long QT interval.
* Due to the fact that [[exon]] 8(atypical Timothy syndrome) is more expressed in heart muscles than that of [[exon]] 8a(classic Timothy syndrome) patients with [[exon]] 8 [[mutation]] have a severe form of long [[QT interval]].


== Causes ==
== Causes ==
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=== Natural History ===
=== Natural History ===


* The [[symptoms]] of Timothy syndrome usually develop in the first decade of life, and start with [[Symptom|symptoms]] such as [[cardiac]], hand/foot, facial, and [[Neurodevelopmental disorders|neurodevelopmental]] symptoms.
* The [[symptoms]] of Timothy syndrome usually develop in the first decade of life, and start with [[Symptom|symptoms]] such as [[cardiac]], [[hand]]/[[foot]], [[facial]], and [[Neurodevelopmental disorders|neurodevelopmental]] symptoms.


=== Complications ===
=== Complications ===
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*[[Sequence analysis]](100% detectable), Targeted [[analysis]] for [[pathogenic]] variants(>95% detectable), [[Gene]]-targeted [[deletion]]/duplication [[analysis]]  of ''[[CACNA1C]]'' [[gene]] testing is the [[Gold standard (test)|gold standard]] test for the [[diagnosis]] of Timothy syndrome.<ref name="pmid221060442">{{cite journal| author=Gillis J, Burashnikov E, Antzelevitch C, Blaser S, Gross G, Turner L et al.| title=Long QT, syndactyly, joint contractures, stroke and novel CACNA1C mutation: expanding the spectrum of Timothy syndrome. | journal=Am J Med Genet A | year= 2012 | volume= 158A | issue= 1 | pages= 182-7 | pmid=22106044 | doi=10.1002/ajmg.a.34355 | pmc=3319791 | url=https://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&tool=sumsearch.org/cite&retmode=ref&cmd=prlinks&id=22106044  }}</ref>
*[[Sequence analysis]](100% detectable), Targeted [[analysis]] for [[pathogenic]] variants(>95% detectable), [[Gene]]-targeted [[deletion]]/duplication [[analysis]]  of ''[[CACNA1C]]'' [[gene]] testing is the [[Gold standard (test)|gold standard]] test for the [[diagnosis]] of Timothy syndrome.<ref name="pmid221060442">{{cite journal| author=Gillis J, Burashnikov E, Antzelevitch C, Blaser S, Gross G, Turner L et al.| title=Long QT, syndactyly, joint contractures, stroke and novel CACNA1C mutation: expanding the spectrum of Timothy syndrome. | journal=Am J Med Genet A | year= 2012 | volume= 158A | issue= 1 | pages= 182-7 | pmid=22106044 | doi=10.1002/ajmg.a.34355 | pmc=3319791 | url=https://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&tool=sumsearch.org/cite&retmode=ref&cmd=prlinks&id=22106044  }}</ref>
*Along with the genetic testing patients also evaluate for following recommendations:
*Along with the [[Genetics|genetic]] testing patients also evaluate for following recommendations:
**[[Electrocardiogram]]([[The electrocardiogram|ECG]])
**[[Electrocardiogram]]([[The electrocardiogram|ECG]])
**[[Echocardiogram]]
**[[Echocardiogram]]
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**Thin vermilion border of the upper [[lip]]
**Thin vermilion border of the upper [[lip]]
**Round [[face]]
**Round [[face]]
**Poor dental enamel with widely spaced teeth  
**Poor [[dental]] [[enamel]] with widely spaced [[teeth]]


=== Heart ===
=== Heart ===
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*[[Extremities]] examination of patients with Timothy syndrome shows [[Webbed toes|webbed]] fingers([[syndactyly]]) and toes.<ref name="pmid23678275">{{cite journal| author=An HS, Choi EY, Kwon BS, Kim GB, Bae EJ, Noh CI et al.| title=Sudden cardiac arrest during anesthesia in a 30-month-old boy with syndactyly: a case of genetically proven Timothy syndrome. | journal=J Korean Med Sci | year= 2013 | volume= 28 | issue= 5 | pages= 788-91 | pmid=23678275 | doi=10.3346/jkms.2013.28.5.788 | pmc=3653096 | url=https://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&tool=sumsearch.org/cite&retmode=ref&cmd=prlinks&id=23678275  }}</ref><ref name="Marks_1995a">{{cite journal | author = Marks M, Whisler S, Clericuzio C, Keating M | title = A new form of long QT syndrome associated with syndactyly. | journal = J Am Coll Cardiol | volume = 25 | issue = 1 | pages = 59-64 | year = 1995 | id = PMID 7798527}}</ref><ref name="Marks_1995b">{{cite journal | author = Marks M, Trippel D, Keating M | title = Long QT syndrome associated with syndactyly identified in females. | journal = Am J Cardiol | volume = 76 | issue = 10 | pages = 744-5 | year = 1995 | id = PMID 7572644}}</ref><ref name="Splawski_2004">{{cite journal | author = Splawski I, Timothy K, Sharpe L, Decher N, Kumar P, Bloise R, Napolitano C, Schwartz P, Joseph R, Condouris K, Tager-Flusberg H, Priori S, Sanguinetti M, Keating M | title = Ca(V)1.2 calcium channel dysfunction causes a multisystem disorder including arrhythmia and autism. | journal = Cell | volume = 119 | issue = 1 | pages = 19-31 | year = 2004 | id = PMID 15454078}}</ref><ref name="Splawski_2005">{{cite journal | author = Splawski I, Timothy K, Decher N, Kumar P, Sachse F, Beggs A, Sanguinetti M, Keating M | title = Severe arrhythmia disorder caused by cardiac L-type calcium channel mutations. | journal = Proc Natl Acad Sci U S A | volume = 102 | issue = 23 | pages = 8089-96; discussion 8086-8 | year = 2005 | id = PMID 15863612}}</ref>
*[[Extremities]] examination of patients with Timothy syndrome shows [[Webbed toes|webbed]] fingers([[syndactyly]]) and toes.<ref name="pmid23678275">{{cite journal| author=An HS, Choi EY, Kwon BS, Kim GB, Bae EJ, Noh CI et al.| title=Sudden cardiac arrest during anesthesia in a 30-month-old boy with syndactyly: a case of genetically proven Timothy syndrome. | journal=J Korean Med Sci | year= 2013 | volume= 28 | issue= 5 | pages= 788-91 | pmid=23678275 | doi=10.3346/jkms.2013.28.5.788 | pmc=3653096 | url=https://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&tool=sumsearch.org/cite&retmode=ref&cmd=prlinks&id=23678275  }}</ref><ref name="Marks_1995a">{{cite journal | author = Marks M, Whisler S, Clericuzio C, Keating M | title = A new form of long QT syndrome associated with syndactyly. | journal = J Am Coll Cardiol | volume = 25 | issue = 1 | pages = 59-64 | year = 1995 | id = PMID 7798527}}</ref><ref name="Marks_1995b">{{cite journal | author = Marks M, Trippel D, Keating M | title = Long QT syndrome associated with syndactyly identified in females. | journal = Am J Cardiol | volume = 76 | issue = 10 | pages = 744-5 | year = 1995 | id = PMID 7572644}}</ref><ref name="Splawski_2004">{{cite journal | author = Splawski I, Timothy K, Sharpe L, Decher N, Kumar P, Bloise R, Napolitano C, Schwartz P, Joseph R, Condouris K, Tager-Flusberg H, Priori S, Sanguinetti M, Keating M | title = Ca(V)1.2 calcium channel dysfunction causes a multisystem disorder including arrhythmia and autism. | journal = Cell | volume = 119 | issue = 1 | pages = 19-31 | year = 2004 | id = PMID 15454078}}</ref><ref name="Splawski_2005">{{cite journal | author = Splawski I, Timothy K, Decher N, Kumar P, Sachse F, Beggs A, Sanguinetti M, Keating M | title = Severe arrhythmia disorder caused by cardiac L-type calcium channel mutations. | journal = Proc Natl Acad Sci U S A | volume = 102 | issue = 23 | pages = 8089-96; discussion 8086-8 | year = 2005 | id = PMID 15863612}}</ref>
*[[Syndactyly]] is due to the failure of [[apoptosis]] on the [[apical]] ectodermal ridge.


== Laboratory Findings ==
== Laboratory Findings ==
There are no [[diagnostic]] laboratory findings associated with Timothy syndrome.
 
* There are no [[diagnostic]] laboratory findings associated with Timothy syndrome.


== Ultrasound ==
== Ultrasound ==
Line 212: Line 215:
== Medical Therapy ==
== Medical Therapy ==


* Pharmacologic medical therapy is recommended among patients with [disease subclass 1], [disease subclass 2], and [disease subclass 3].
*[[Verapamil]], [[mexiletine]] and [[ranolazine]] are also effective in treating the patients of Timothy syndrome.<ref name="JacobsKnight2006">{{cite journal|last1=Jacobs|first1=Avrum|last2=Knight|first2=Bradley P.|last3=McDonald|first3=Karen T.|last4=Burke|first4=Martin C.|title=Verapamil decreases ventricular tachyarrhythmias in a patient with Timothy syndrome (LQT8)|journal=Heart Rhythm|volume=3|issue=8|year=2006|pages=967–970|issn=15475271|doi=10.1016/j.hrthm.2006.04.024}}</ref><ref name="pmid20883512">{{cite journal| author=Shah DP, Baez-Escudero JL, Weisberg IL, Beshai JF, Burke MC| title=Ranolazine safely decreases ventricular and atrial fibrillation in Timothy syndrome (LQT8). | journal=Pacing Clin Electrophysiol | year= 2012 | volume= 35 | issue= 3 | pages= e62-4 | pmid=20883512 | doi=10.1111/j.1540-8159.2010.02913.x | pmc= | url=https://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&tool=sumsearch.org/cite&retmode=ref&cmd=prlinks&id=20883512  }}</ref><ref name="pmid23580742">{{cite journal| author=Gao Y, Xue X, Hu D, Liu W, Yuan Y, Sun H et al.| title=Inhibition of late sodium current by mexiletine: a novel pharmotherapeutical approach in timothy syndrome. | journal=Circ Arrhythm Electrophysiol | year= 2013 | volume= 6 | issue= 3 | pages= 614-22 | pmid=23580742 | doi=10.1161/CIRCEP.113.000092 | pmc= | url=https://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&tool=sumsearch.org/cite&retmode=ref&cmd=prlinks&id=23580742  }}</ref><ref name="pmid282119896">{{cite journal| author=Sepp R, Hategan L, Bácsi A, Cseklye J, Környei L, Borbás J et al.| title=Timothy syndrome 1 genotype without syndactyly and major extracardiac manifestations. | journal=Am J Med Genet A | year= 2017 | volume= 173 | issue= 3 | pages= 784-789 | pmid=28211989 | doi=10.1002/ajmg.a.38084 | pmc= | url=https://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&tool=sumsearch.org/cite&retmode=ref&cmd=prlinks&id=28211989  }}</ref><ref name="pmid235807422">{{cite journal| author=Gao Y, Xue X, Hu D, Liu W, Yuan Y, Sun H et al.| title=Inhibition of late sodium current by mexiletine: a novel pharmotherapeutical approach in timothy syndrome. | journal=Circ Arrhythm Electrophysiol | year= 2013 | volume= 6 | issue= 3 | pages= 614-22 | pmid=23580742 | doi=10.1161/CIRCEP.113.000092 | pmc= | url=https://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&tool=sumsearch.org/cite&retmode=ref&cmd=prlinks&id=23580742  }}</ref>
* Pharmacologic medical therapies for Timothy syndrome include beta blockers which are the mainstay of treatment.
*[[Beta blockers|Beta-blockers]] helps in controlling the [[QT interval]] prolongation which in-turn helps in  preventing [[ventricular tachycardia]], which is the main cause of death in patients with Timothy syndrome.
*[[Verapamil]], mexiletine and [[ranolazine]] are also effective in treating the patients of Timothy syndrome.<ref name="JacobsKnight2006">{{cite journal|last1=Jacobs|first1=Avrum|last2=Knight|first2=Bradley P.|last3=McDonald|first3=Karen T.|last4=Burke|first4=Martin C.|title=Verapamil decreases ventricular tachyarrhythmias in a patient with Timothy syndrome (LQT8)|journal=Heart Rhythm|volume=3|issue=8|year=2006|pages=967–970|issn=15475271|doi=10.1016/j.hrthm.2006.04.024}}</ref><ref name="pmid20883512">{{cite journal| author=Shah DP, Baez-Escudero JL, Weisberg IL, Beshai JF, Burke MC| title=Ranolazine safely decreases ventricular and atrial fibrillation in Timothy syndrome (LQT8). | journal=Pacing Clin Electrophysiol | year= 2012 | volume= 35 | issue= 3 | pages= e62-4 | pmid=20883512 | doi=10.1111/j.1540-8159.2010.02913.x | pmc= | url=https://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&tool=sumsearch.org/cite&retmode=ref&cmd=prlinks&id=20883512  }}</ref><ref name="pmid23580742">{{cite journal| author=Gao Y, Xue X, Hu D, Liu W, Yuan Y, Sun H et al.| title=Inhibition of late sodium current by mexiletine: a novel pharmotherapeutical approach in timothy syndrome. | journal=Circ Arrhythm Electrophysiol | year= 2013 | volume= 6 | issue= 3 | pages= 614-22 | pmid=23580742 | doi=10.1161/CIRCEP.113.000092 | pmc= | url=https://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&tool=sumsearch.org/cite&retmode=ref&cmd=prlinks&id=23580742  }}</ref><ref name="pmid282119896">{{cite journal| author=Sepp R, Hategan L, Bácsi A, Cseklye J, Környei L, Borbás J et al.| title=Timothy syndrome 1 genotype without syndactyly and major extracardiac manifestations. | journal=Am J Med Genet A | year= 2017 | volume= 173 | issue= 3 | pages= 784-789 | pmid=28211989 | doi=10.1002/ajmg.a.38084 | pmc= | url=https://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&tool=sumsearch.org/cite&retmode=ref&cmd=prlinks&id=28211989  }}</ref><ref name="pmid235807422">{{cite journal| author=Gao Y, Xue X, Hu D, Liu W, Yuan Y, Sun H et al.| title=Inhibition of late sodium current by mexiletine: a novel pharmotherapeutical approach in timothy syndrome. | journal=Circ Arrhythm Electrophysiol | year= 2013 | volume= 6 | issue= 3 | pages= 614-22 | pmid=23580742 | doi=10.1161/CIRCEP.113.000092 | pmc= | url=https://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&tool=sumsearch.org/cite&retmode=ref&cmd=prlinks&id=23580742  }}</ref>
*Beta-blockers helps in controlling the QT interval prolongation which in-turn helps in  preventing ventricular tachycardia, which is the main cause of death in patients with Timothy syndrome.
*In [[Patient|patients]] with Timothy syndrome despite treated with the [[Beta blockers|beta-blockers]] risk of [[cardiac]] events still persists.<ref name="pmid19118258">{{cite journal| author=Vincent GM, Schwartz PJ, Denjoy I, Swan H, Bithell C, Spazzolini C et al.| title=High efficacy of beta-blockers in long-QT syndrome type 1: contribution of noncompliance and QT-prolonging drugs to the occurrence of beta-blocker treatment "failures". | journal=Circulation | year= 2009 | volume= 119 | issue= 2 | pages= 215-21 | pmid=19118258 | doi=10.1161/CIRCULATIONAHA.108.772533 | pmc= | url=https://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&tool=sumsearch.org/cite&retmode=ref&cmd=prlinks&id=19118258  }}</ref>
*In [[Patient|patients]] with Timothy syndrome despite treated with the [[Beta blockers|beta-blockers]] risk of [[cardiac]] events still persists.<ref name="pmid19118258">{{cite journal| author=Vincent GM, Schwartz PJ, Denjoy I, Swan H, Bithell C, Spazzolini C et al.| title=High efficacy of beta-blockers in long-QT syndrome type 1: contribution of noncompliance and QT-prolonging drugs to the occurrence of beta-blocker treatment "failures". | journal=Circulation | year= 2009 | volume= 119 | issue= 2 | pages= 215-21 | pmid=19118258 | doi=10.1161/CIRCULATIONAHA.108.772533 | pmc= | url=https://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&tool=sumsearch.org/cite&retmode=ref&cmd=prlinks&id=19118258  }}</ref>
**Preferred regimen (1): [[Nadolol]]  1–1.5 mg/kg/day administered once a day in patients ≥12 years of age, divided twice daily in [[Infant|infants]] and [[children]]
**Preferred regimen (1): [[Nadolol]]  1–1.5 mg/kg/day administered once a day in patients ≥12 years of age, divided twice daily in [[Infant|infants]] and [[children]]
**Preferred regimen (2): [[Verapamil]] 120 mg twice a day and by decreasing the beta blocker dosage to half.
**Preferred regimen (2): [[Verapamil]] 120 mg twice a day and by decreasing the [[beta blocker]] dosage to half.
*
*
* Empiric therapy for [disease name] depends on [disease factor 1] and [disease factor 2].
* Patients with [disease subclass 1] are treated with [therapy 1], whereas patients with [disease subclass 2] are treated with [therapy 2].


== Interventions ==
== Interventions ==
Line 240: Line 239:
'''Pacemaker'''
'''Pacemaker'''


* In patients with Timothy syndrome placing a pacemaker is going to help in controlling the 2:1 AV block and bradycardia.
* In patients with Timothy syndrome placing a [[pacemaker]] is going to help in controlling the 2:1 [[AV block]] and [[bradycardia]].


== Surgery ==
== Surgery ==


* Surgery is not the first-line treatment option for patients with Timothy syndrome. Surgery is usually reserved for patients with either:
* Surgery is not the first-line treatment option for patients with Timothy syndrome. Surgery is usually reserved for patients with either:
** Syndactyly: Surgical release of syndactyly
**[[Syndactyly]]: Surgical release of [[syndactyly]].<ref name="pmid27895538">{{cite journal| author=Braun TL, Trost JG, Pederson WC| title=Syndactyly Release. | journal=Semin Plast Surg | year= 2016 | volume= 30 | issue= 4 | pages= 162-170 | pmid=27895538 | doi=10.1055/s-0036-1593478 | pmc=5115922 | url=https://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&tool=sumsearch.org/cite&retmode=ref&cmd=prlinks&id=27895538  }}</ref>


== Primary Prevention ==
== Primary Prevention ==
Line 255: Line 254:
*Effective measures for the [[secondary prevention]] of Timothy syndrome include:<ref name="pmid203015793">{{cite journal| author=Adam MP, Ardinger HH, Pagon RA, Wallace SE, Bean LJH, Stephens K et al.| title=GeneReviews® | journal= | year= 1993 | volume=  | issue=  | pages=  | pmid=20301579 | doi= | pmc= | url= }}</ref>
*Effective measures for the [[secondary prevention]] of Timothy syndrome include:<ref name="pmid203015793">{{cite journal| author=Adam MP, Ardinger HH, Pagon RA, Wallace SE, Bean LJH, Stephens K et al.| title=GeneReviews® | journal= | year= 1993 | volume=  | issue=  | pages=  | pmid=20301579 | doi= | pmc= | url= }}</ref>
**Taking special care while giving the [[anesthesia]] due to the risk of [[cardiac]] [[arrhythmias]].
**Taking special care while giving the [[anesthesia]] due to the risk of [[cardiac]] [[arrhythmias]].
**Monitoring of serum [[glucose]] levels due to intractable [[hypoglycemia]] in patients with Timothy syndrome.


==References==
==References==

Latest revision as of 22:36, 13 April 2020

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Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]; Associate Editor(s)-in-Chief: Vamsikrishna Gunnam M.B.B.S [2]

Synonyms and keywords: Long QT syndrome 8; LQT8; Long QT syndrome with syndactyly; TS

Overview

Timothy syndrome is a rare syndrome that follows autosomal dominant inheritance pattern. Timothy syndrome is a multisystem disorder characterized by physiological and developmental defects which include long QT-prolongation, arrhythmias, structural heart defects, syndactyly and autism spectrum disorders. Timothy syndrome may be classified into 2 groups, classical form(type-1) and atypical form(type-2). Timothy syndrome caused by mutations in CACNA1C, which encodes for calcium channel α subunit. Timothy syndrome often ends in early death. The United States of America in order to categorize a condition as a rare disease it should affect fewer than 200,000 people. Rare diseases also called as orphan diseases. Orphan Drug Act was passed in 1983 by congress for the rare diseases. Today an average of 25-30 million Americans have been reported with rare diseases. The number of people with individual rare disease may be less but overall the number of people with rare diseases are large in number.

Historical Perspective

  • Timothy syndrome was first discovered by Reichenbach and Marks, in 1992.[1][2]
  • In 1995, Splawski, Reichenbach, and Marks were the first to give the name Timothy syndrome in the honor of Dr.Katherine W. Timothy who did the phenotypic analysis.[3]

Classification

  • Timothy syndrome may be classified into 2 groups as follows:[4][5][6][7]
Type Gene Protein involved Location Mutations Inheritance pattern Symptoms
Classic Timothy syndrome CACNA1C Voltage-dependent L-type calcium channel subunit alpha-1C 12p13.33 Exon 8 a Autosomal dominant Long QT syndrome with syndactyly
Atypical Timothy syndrome CACNA1C Voltage-dependent L-type calcium channel subunit alpha-1C 12p13.33 Exon 8 Autosomal dominant A very severe form of long QT syndrome without syndactyly

Pathophysiology

  • Due to the fact that exon 8(atypical Timothy syndrome) is more expressed in heart muscles than that of exon 8a(classic Timothy syndrome) patients with exon 8 mutation have a severe form of long QT interval.

Causes

Genetic Causes

Differentiating Timothy syndrome from other Diseases

Epidemiology and Demographics

Incidence

  • The incidence of timothy syndrome is unknown worldwide.
  • Only 20 cases were reported worldwide.

Prevalence

  • The prevalence of timothy syndrome is less than 1 per 100,000 individuals worldwide.

Mortality rate

  • In patients with timothy syndrome the average age of death is 2.5 years

Age

  • Timothy syndrome commonly affects individuals of younger age group, the median age of diagnosis is usally within the first few days after birth.

Race

  • There is no racial predilection to Timothy syndrome.

Gender

  • Timothy syndrome affects men and women equally.

Risk Factors

Screening

  • There is insufficient evidence to recommend routine screening for Timothy syndrome.

Natural History, Complications, Prognosis

Natural History

Complications

Prognosis

  • The prognosis for patients diagnosed with Timothy syndrome is grim.
  • The average age of death is 2.5 years in patients with Timothy syndrome.[28] [29]

Diagnosis

Diagnostic study of choice

Symptoms

Common Symptoms

Common symptoms of Timothy syndrome include:[31][32]

Less Common Symptoms

Less common symptoms of Timothy syndrome include:[33][34]

Electrocardiogram

Physical Examination

Characteristic phenotypic features of Timothy syndrome: bald head and lower–set ears, webbing of fingers and toes. Case courtesy by U. Krause Et Al[42]

HEENT

Heart

Neurodevelopmental

Extremities

Laboratory Findings

  • There are no diagnostic laboratory findings associated with Timothy syndrome.

Ultrasound

  • Ultrasound may be helpful in the diagnosis of syndactyly during pregnancy with Timothy syndrome patients.

X Ray, CT scan and MRI scan

Medical Therapy

Interventions

  • The feasibility of interventions depends on the severity of Timothy syndrome patients at the time of diagnosis which include:[57][58]

Implantable cardioverter-defibrillators (ICDs)

  • ICDs are good alternative choice of treatment for the patients who are resistant to beta blockers.

Left cardiac sympathetic denervation (LCSD)

Pacemaker

Surgery

  • Surgery is not the first-line treatment option for patients with Timothy syndrome. Surgery is usually reserved for patients with either:

Primary Prevention

Secondary Prevention

References

  1. 1.0 1.1 Reichenbach H, Meister EM, Theile H (1992). "[The heart-hand syndrome. A new variant of disorders of heart conduction and syndactylia including osseous changes in hands and feet]". Kinderarztl Prax. 60 (2): 54–6. PMID 1318983.
  2. Marks ML, Trippel DL, Keating MT (1995). "Long QT syndrome associated with syndactyly identified in females". Am J Cardiol. 76 (10): 744–5. doi:10.1016/s0002-9149(99)80216-1. PMID 7572644.
  3. Gillis J, Burashnikov E, Antzelevitch C, Blaser S, Gross G, Turner L; et al. (2012). "Long QT, syndactyly, joint contractures, stroke and novel CACNA1C mutation: expanding the spectrum of Timothy syndrome". Am J Med Genet A. 158A (1): 182–7. doi:10.1002/ajmg.a.34355. PMC 3319791. PMID 22106044.
  4. Schultz D, Mikala G, Yatani A, Engle DB, Iles DE, Segers B; et al. (1993). "Cloning, chromosomal localization, and functional expression of the alpha 1 subunit of the L-type voltage-dependent calcium channel from normal human heart". Proc Natl Acad Sci U S A. 90 (13): 6228–32. doi:10.1073/pnas.90.13.6228. PMC 46901. PMID 8392192.
  5. Hiippala A, Tallila J, Myllykangas S, Koskenvuo JW, Alastalo TP (2015). "Expanding the phenotype of Timothy syndrome type 2: an adolescent with ventricular fibrillation but normal development". Am J Med Genet A. 167A (3): 629–34. doi:10.1002/ajmg.a.36924. PMID 25691416.
  6. Soldatov NM, Bouron A, Reuter H (1995). "Different voltage-dependent inhibition by dihydropyridines of human Ca2+ channel splice variants". J Biol Chem. 270 (18): 10540–3. doi:10.1074/jbc.270.18.10540. PMID 7737988.
  7. Lyford GL, Strege PR, Shepard A, Ou Y, Ermilov L, Miller SM; et al. (2002). "alpha(1C) (Ca(V)1.2) L-type calcium channel mediates mechanosensitive calcium regulation". Am J Physiol Cell Physiol. 283 (3): C1001–8. doi:10.1152/ajpcell.00140.2002. PMID 12176756.
  8. Walsh MA, Turner C, Timothy KW, Seller N, Hares DL, James AF; et al. (2018). "A multicentre study of patients with Timothy syndrome". Europace. 20 (2): 377–385. doi:10.1093/europace/euw433. PMID 28371864.
  9. Baurand A, Falcon-Eicher S, Laurent G, Villain E, Bonnet C, Thauvin-Robinet C; et al. (2017). "Incomplete Timothy syndrome secondary to a mosaic mutation of the CACNA1C gene diagnosed using next-generation sequencing". Am J Med Genet A. 173 (2): 531–536. doi:10.1002/ajmg.a.38045. PMID 27868338.
  10. Cheng EP, Yuan C, Navedo MF, Dixon RE, Nieves-Cintrón M, Scott JD; et al. (2011). "Restoration of normal L-type Ca2+ channel function during Timothy syndrome by ablation of an anchoring protein". Circ Res. 109 (3): 255–61. doi:10.1161/CIRCRESAHA.111.248252. PMC 3151468. PMID 21700933.
  11. Splawski I, Timothy KW, Sharpe LM, Decher N, Kumar P, Bloise R; et al. (2004). "Ca(V)1.2 calcium channel dysfunction causes a multisystem disorder including arrhythmia and autism". Cell. 119 (1): 19–31. doi:10.1016/j.cell.2004.09.011. PMID 15454078.
  12. Dixon RE, Cheng EP, Mercado JL, Santana LF (2012). "L-type Ca2+ channel function during Timothy syndrome". Trends Cardiovasc Med. 22 (3): 72–6. doi:10.1016/j.tcm.2012.06.015. PMC 3640256. PMID 22999068.
  13. Dick IE, Joshi-Mukherjee R, Yang W, Yue DT (2016). "Arrhythmogenesis in Timothy Syndrome is associated with defects in Ca(2+)-dependent inactivation". Nat Commun. 7: 10370. doi:10.1038/ncomms10370. PMC 4740114. PMID 26822303.
  14. Sepp R, Hategan L, Bácsi A, Cseklye J, Környei L, Borbás J; et al. (2017). "Timothy syndrome 1 genotype without syndactyly and major extracardiac manifestations". Am J Med Genet A. 173 (3): 784–789. doi:10.1002/ajmg.a.38084. PMID 28211989.
  15. De Oliveira CC, Figueiredo EA, Gazzinelli G, Howells RE, Pellegrino J (1975). "Biochemical changes in the transformation of Schistosoma mansoni cercariae to schistosomules". Comp Biochem Physiol B. 51 (4): 417–20. doi:10.1016/0305-0491(75)90031-0. PMID 1149428.
  16. Betzenhauser MJ, Pitt GS, Antzelevitch C (2015). "Calcium Channel Mutations in Cardiac Arrhythmia Syndromes". Curr Mol Pharmacol. 8 (2): 133–42. doi:10.2174/1874467208666150518114857. PMC 4762596. PMID 25981977.
  17. Corona-Rivera JR, Barrios-Prieto E, Nieto-García R, Bloise R, Priori S, Napolitano C; et al. (2015). "Unusual retrospective prenatal findings in a male newborn with Timothy syndrome type 1". Eur J Med Genet. 58 (6–7): 332–5. doi:10.1016/j.ejmg.2015.04.001. PMID 25882468.
  18. Boczek NJ, Miller EM, Ye D, Nesterenko VV, Tester DJ, Antzelevitch C; et al. (2015). "Novel Timothy syndrome mutation leading to increase in CACNA1C window current". Heart Rhythm. 12 (1): 211–9. doi:10.1016/j.hrthm.2014.09.051. PMC 4907369. PMID 25260352.
  19. Adam MP, Ardinger HH, Pagon RA, Wallace SE, Bean LJH, Stephens K; et al. (1993). "GeneReviews®". PMID 20301308.
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