WBR0312

Author	[[PageAuthor::William J Gibson (Reviewed by Yazan Daaboul, M.D.)]]
Exam Type	ExamType::USMLE Step 1
Main Category	MainCategory::Genetics
Sub Category	SubCategory::Reproductive, SubCategory::General Principles
Prompt	[[Prompt::A newborn girl is born via cesarean section to a 42-year-old primigravid woman. The child has microcephaly with a prominent occiput, low-set ears, cleft palate, and rocker-bottom feet with webbed toes. An image of the patient’s hands is shown below. What is the median lifespan that is associated with this patient's condition? ]]
Answer A	AnswerA::50 to 60 years
Answer A Explanation	AnswerAExp::Sixty years is the median lifespan of patients with Down Syndrome. However, many patients with Down syndrome are affected by Alzheimer’s disease between the ages of 40 and 50.
Answer B	AnswerB::10 to 15 years
Answer B Explanation	AnswerBExp::Ten years is the median lifespan of patients with progerioid syndromes such as Hutchinson-Gilford progeria.
Answer C	AnswerC::1 to 2 years
Answer C Explanation	AnswerCExp::One year is the median lifespan of patients with Patau syndrome. Patau syndrome is caused by an extra copy of chromosome 13 (trisomy 13).
Answer D	AnswerD::1 to 2 weeks
Answer D Explanation	AnswerDExp::One week (5-15 days) is the median lifespan of patients with Edwards' syndrome if they survive to birth.
Answer E	AnswerE::1 to 2 days
Answer E Explanation	AnswerEExp::The median lifespan of anencephaly is on the order of approximately one day.
Right Answer	RightAnswer::D
Explanation	[[Explanation::Edwards' syndrome is a chromosomal abnormality caused by the presence of all or part of an extra 18th chromosome (trisomy 18). Approximately 80% of patients with Edward's syndrome are female. The majority of fetuses with the syndrome die before birth; those who survive have a median lifespan of approximately 1 to 2 weeks. Less than 10% of patients with Edwards' syndrome live beyond 1 year. The physical characteristics of Edwards' syndrome include the following: Intellectual disability Clenched fingers (shown in the picture above) Micrognathia Microcephaly Prominent occiput Low-set, dysmorphic ears Cleft lip and/or palate Webbing of the toes Rocker bottom feet Educational Objective: Edwards' syndrome is a chromosomal abnormality of chromosome 18 (trisomy 18) with severe abnormal facies and symptoms. The majority of patients with Edwards' syndrome die before birth. Among those who survive, the median lifespan of live births is approximately 1 to 2 weeks. References: First Aid 2014 page 90]]
Approved	Approved::Yes
Keyword	WBRKeyword::Edwards syndrome, WBRKeyword::Edwards' syndrome, WBRKeyword::Trisomy 18, WBRKeyword::Chromosome, WBRKeyword::Chromosomal Abnormality, WBRKeyword::Aneuploidy, WBRKeyword::Newborn, WBRKeyword::Median lifespan, WBRKeyword::Lifespan, WBRKeyword::Median life expectancy, WBRKeyword::Life expectancy
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