USMLE

Turner Syndrome

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Chromosomal Abnormalities
  1. Down Syndrome (Trisomy 21)
  2. Edwards Syndrome (Trisomy 18)
  3. Patau Syndrome (Trisomy 13)
  4. Klinefelter Syndrome
  5. Turner Syndrome
  6. Williams Syndrome
  7. Cri du Chat Syndrome
  8. Imprinting

Turner Syndrome, also known as 45,X or 45,XO, is a chromosomal defect affecting females that results from the loss or partial loss of a X-chromosome.

The lack of an second X chromosome results in defective ovarian development. This may present in adolescent females as amenorrhea (lack of menses), with a lack of secondary sex characteristics. Ultrasound imaging reveals streak ovaries. Defective ovaries result in reduced estrogen levels, with compensatory elevation in LH and FSH.

Other physical findings include a short statue, webbed neck, cystic hygroma, and lymphedema. Cardiovascular complications include coarctation of the aorta, and a bicuspid aortic valve (increased risk for aortic stenosis).

Find Turner Syndrome and more Chromosomal Abnormalities among Pixorize's visual mnemonics for the USMLE Step 1 and NBME Shelf Exams.