WBR263
| Author | [[PageAuthor::Ogheneochuko Ajari, MB.BS, MS [1] (Reviewed by Will Gibson)]] |
|---|---|
| Exam Type | ExamType::USMLE Step 1 |
| Main Category | MainCategory::Embryology, 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:
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. |
| 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:: |