WBR263

Author	[[PageAuthor::Ogheneochuko Ajari, MB.BS, MS [1] (Reviewed by Will Gibson)]]
Exam Type	ExamType::USMLE Step 1
Main Category	MainCategory::Embryology
Sub Category	SubCategory::General Principles
Prompt	[[Prompt::A 12 month old female was brought to the physician’s office with complaints of fever, vomiting and difficulty with breathing. The mother is a chronic alcoholic and consumed alcohol excessively throughout the child’s pregnancy. A month ago, the child was diagnosed with fetal alcohol syndrome. Physical examination shows microcephaly, facial abnormalities, a heart murmur and developmental delay. Which one of the following errors most likely occurred in the embryonic period?]]
Answer A	AnswerA::Aplasia
Answer A Explanation	AnswerAExp::Aplasia refers to the failure of an organ to develop despite the presence of primordial tissue.
Answer B	AnswerB::Hypoplasia
Answer B Explanation	AnswerBExp::Hypoplasia is incomplete organ development with the presence of primordial tissue.
Answer C	AnswerC::Agenesis
Answer C Explanation	AnswerCExp::Agenesis refers to the failure of an organ to develop due to the absence of primordial tissue.
Answer D	AnswerD::Deformation
Answer D Explanation	AnswerDExp::Deformation is extrinsic disruption of an organ or tissue; it occurs after the embryonic period.
Answer E	AnswerE::Malformation
Answer E Explanation	AnswerEExp::Alcohol exposure during pregnancy causes tissue and central nervous system malformations. The effects of alcohol in the CNS appear to be due in part to negative effects on cell migration.
Right Answer	RightAnswer::E
Explanation	[[Explanation::The patient in this question has Fetal alcohol syndrome which is a leading cause of congenital malformation and intellectual disability in the United States. Newborns of mothers that consumed significant quantities of alcohol during pregnancy have an increased incidence of congenital abnormalities. These abnormalities include: pre-and postnatal developmental retardation microcephaly holopresencephaly facial abnormalities limb dislocation heart and lung fistulas. The question prompt states that the child exhibits microcephaly, facial abnormalities, both of which are tissue malformations. The patient's hear murmur is likely also caused by tissue malformation, but echocardiography would be required to confirm. Malformation (Choice E) refers to intrinsic disruption of tissue structure and typically occurs during the embryonic period of development (3rd -8th week). Alcohol, a teratogen, exerts its effect during this stage of fetal development. Defective cell migration is thought to mediate a substantial fraction of alcohol's teratogenicity. Educational Objective: Fetal alcohol syndrome is caused by the teratogen alcohol which causes congenital malformations, an error in organ morphogenesis in the embryonic period to organogenesis (3rd – 8th weeks). References: Riley, Edward P., M. Alejandra Infante, and Kenneth R. Warren. "Fetal alcohol spectrum disorders: an overview." Neuropsychology review 21.2 (2011): 73-80. First Aid 2015 page 561]]
Approved	Approved::Yes
Keyword	WBRKeyword::EtOH, WBRKeyword::Fetal Alcohol Syndrome, WBRKeyword::FAS, WBRKeyword::Alcohol, WBRKeyword::Teratogen, WBRKeyword::Substance abuse, WBRKeyword::Embryology, WBRKeyword::Embryo, WBRKeyword::Development
Linked Question	Linked::
Order in Linked Questions	LinkedOrder::