Alpha 1-antitrypsin deficiency causes: Difference between revisions

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{{Alpha 1-antitrypsin deficiency}}
{{Alpha 1-antitrypsin deficiency}}
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==Overview==
==Overview==
Alpha 1-antitrypsin deficiency (A1AD) occurs largely in part because of a mutation of chromosome 14.
Alpha1-antitrypsin deficiency (AATD) is caused by a [[Mutations|mutation]] in the [[Gene|SERPINA1 gene]]. SERPINA1 is located on [[chromosome 14]].


==Causes==
==Causes==
Alpha-1 antitrypsin (AAT) is a type of protein called a "protease inhibitor." It is made in the liver and it works to protect the lungs and liver. AAT deficiency means there is not enough of this protein in the body. It is caused by a genetic defect in the formation of the 14th chromosome.
*Alpha1-antitrypsin deficiency (AATD) is caused by a [[mutation]] in the [[Gene|SERPINA1  gene]].<ref name="pmid28927525">{{cite journal |vauthors=Hazari YM, Bashir A, Habib M, Bashir S, Habib H, Qasim MA, Shah NN, Haq E, Teckman J, Fazili KM |title=Alpha-1-antitrypsin deficiency: Genetic variations, clinical manifestations and therapeutic interventions |journal=Mutat. Res. |volume=773 |issue= |pages=14–25 |year=2017 |pmid=28927525 |doi=10.1016/j.mrrev.2017.03.001 |url=}}</ref><ref name="pmid27399863">{{cite journal |vauthors=Stoller JK |title=Alpha-1 antitrypsin deficiency: An underrecognized, treatable cause of COPD |journal=Cleve Clin J Med |volume=83 |issue=7 |pages=507–14 |year=2016 |pmid=27399863 |doi=10.3949/ccjm.83a.16031 |url=}}</ref>
 
*SERPINA1 is located on [[chromosome 14]] and is highly pleomorphic, with more than 100 [[Alleles|allelic variants]].This gene instructs the body to make a [[protein]] called [[alpha-1 antitrypsin]] (AAT), which [[Function (biology)|functions]] to [[Inhibition|inhibit]] [[neutrophil elastase]] [[enzyme]].
===Genetics===
*[[Neutrophil elastase]] helps the body fight [[infections]], but it can also attack healthy tissue in the [[lung]] if not inactivated by AAT. Alpha1-antiprotease functions to protect the lungs from unregulated [[Proteases|protease activity]].
The alpha-1 AT gene has been located on the long arm of chromosome 14, and has been successfully been sequenced and cloned. There have been 75 different alleles for alpha-1 AT variants that have been described, but only 10-15 are associated with severe alpha-1 AT deficiency. Each allele has been given a letter code based upon electrophoretic mobility.  By far, the most common severe deficient variant is the Z allele, which is produced by substitution of a lysine for glutamate at position 342 of the molecule. This accounts for 95% of the clinically recognized cases of severe alpha-1 AT deficiency. The 75 alleles can basically be divided into four groups:
*[[Mutations]] associated with AAT can result in:
* Normal – M alleles (normal phenotype is MM), found in 90% of the U.S. population, patients have normal lung function.
**Deficient amount of AAT in the body.
* Deficient – Z allele (carried by 2-3% of the U.S. Caucasian population), have plasma levels of alpha-1 AT that are < 35% of normal.
**Complete absence of AAT.
* Null – No detectable alpha-1 AT.  Least common and most severe form of the disease.
**A form of AAT that does not work effectively to protect healthy [[lung]] tissue.  
* Dysfunctional – Patients have a normal alpha-1 AT level, but the enzyme does not function properly.
*SERPINA1 [[Mutations|mutation]] allows [[neutrophil elastase]] to destroy [[Lung|lung tissue]], causing [[lung disease]].
*In addition, the accumulation of intrahepatic [[Alpha1 antitrypsin|alpha1-antitrypsin]] can build up in the [[liver]] and can result in [[apoptosis]] of [[hepatocytes]].  
*The severity of AATD may also be worsened by environmental factors such as exposure to tobacco smoke, dust, and chemicals. This initially presents as laboratory abnormalities on [[Liver function tests|liver function test]], but can progress to [[hepatitis]], followed by [[fibrosis]] and [[cirrhosis]].


==References==
==References==
{{reflist|2}}
{{reflist|2}}
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Latest revision as of 16:43, 23 January 2018

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Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]; Associate Editor(s)-in-Chief: Mazia Fatima, MBBS [2]

Overview

Alpha1-antitrypsin deficiency (AATD) is caused by a mutation in the SERPINA1 gene. SERPINA1 is located on chromosome 14.

Causes

References

  1. Hazari YM, Bashir A, Habib M, Bashir S, Habib H, Qasim MA, Shah NN, Haq E, Teckman J, Fazili KM (2017). "Alpha-1-antitrypsin deficiency: Genetic variations, clinical manifestations and therapeutic interventions". Mutat. Res. 773: 14–25. doi:10.1016/j.mrrev.2017.03.001. PMID 28927525.
  2. Stoller JK (2016). "Alpha-1 antitrypsin deficiency: An underrecognized, treatable cause of COPD". Cleve Clin J Med. 83 (7): 507–14. doi:10.3949/ccjm.83a.16031. PMID 27399863.


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