A newborn girl with 45,X karyotype presents with webbed neck, lymphedema of hands and feet, and coarctation of the aorta. The lymphedema results from:

• A Cardiac failure from coarctation causing systemic venous hypertension
• B Elevated estrogen levels stimulating lymphangiogenesis in aberrant locations
• C Hypoplasia of lymphatic channels due to haploinsufficiency of genes on the second X chromosome ✓
• D Turner syndrome-specific VEGF-C mutation impairing lymph vessel maturation

Explanation

Turner syndrome (45,X) results from monosomy X; genes on the short arm of the second X chromosome that escape X-inactivation are haploinsufficient. Loss of one copy of lymphangiogenic genes (e.g., SHOX, FOXC2-region) on Xp leads to hypoplasia of lymphatic vessels, producing the characteristic congenital lymphedema (nuchal cystic hygroma in utero manifesting as webbed neck, and peripheral lymphedema at birth).

Reference: Robbins & Cotran Pathologic Basis of Disease, 10th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.