WBR0312

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Author PageAuthor::William J Gibson
Exam Type ExamType::USMLE Step 1
Main Category MainCategory::Genetics
Sub Category SubCategory::Reproductive, SubCategory::General Principles
Prompt [[Prompt::A newborn female 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 life expectancy of this child?

Center]]

Answer A AnswerA::60 years
Answer A Explanation AnswerAExp::'''Incorrect:''' This is the life expectancy of Down Syndrome patients. However, many Down syndrome patients begin to be affected by Alzheimer’s disease between the ages of 40 and 50.
Answer B AnswerB::10-15 years
Answer B Explanation AnswerBExp::'''Incorrect:''' This is the life expectancy of patients with progerioid syndromes such as Hutchinson-Gilford progeria.
Answer C AnswerC::1 year
Answer C Explanation AnswerCExp::'''Incorrect:''' This is the life expectancy of Patau syndrome patients. Patau syndrome is caused by an extra copy of chromosome 13.
Answer D AnswerD::1 week
Answer D Explanation AnswerDExp::'''Correct:''' The life expectancy of Edwards syndrome patients is around 1 week if they survive to birth.
Answer E AnswerE::1 day
Answer E Explanation AnswerEExp::'''Incorrect:''' This is the life expectancy of a twitter trend.
Right Answer RightAnswer::D
Explanation [[Explanation::Explanation: The patient in this vignette has Edward’s syndrome. Edward’s syndrome is a chromosomal abnormality caused by the presence of all or part of an extra 18th chromosome. Around 80 percent of Edwards syndrome patients are female. The majority of fetuses with the syndrome die before birth; those who survive have a median life expectancy of around 1 week. The physical characteristics of Edwards Syndrome include the following:
  • clenched fingers
  • small jaw
  • small head
  • prominent back portion of the skull (occiput)
  • low-set, malformed ears
  • cleft lip / palate
  • webbing of the toes
  • “rocker bottom” feet

Educational Objective: Edwards syndrome is a chromosomal abnormality of chromosome 18 with severe symptoms; the life expectancy of live births is around one week.

References: First Aid 2012 page 93
Educational Objective:
References: ]]

Approved Approved::Yes
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