WBR0312

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Author [[PageAuthor::William J Gibson (Reviewed by Yazan Daaboul, M.D.)]]
Exam Type ExamType::USMLE Step 1
Main Category MainCategory::Genetics
Sub Category 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::Among those who survive, patients with Edwards' syndrome have a median lifespan of approximately 1 week (5 to 15 days).
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. Fewer 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: Image: Attribution to "Overlapping fingers.JPG" uploaded by user:Bobjgalindo licensed under the GNU Free Documentation license. commons.wikimedia.org. Retrieved Jan 9 2015.
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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