- Down Syndrome (Trisomy 21)
- Edwards Syndrome (Trisomy 18)
- Patau Syndrome (Trisomy 13)
- Klinefelter Syndrome
- Turner Syndrome
- Williams Syndrome
- Cri du Chat Syndrome
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.