Question

Webbed neck, short stature, low posterior hairline. What is the diagnosis?

• A. Turner syndrome
• B. Down syndrome
• C. Patau syndrome
• D. Edwards syndrome

Hint:

Think about which chromosomal syndrome specifically in females presents with webbed neck and short stature due to an X chromosome abnormality.

Answer 1

The Correct Option is A

Turner Syndrome -- Key facts:

Karyotype: 45,X (monosomy X) -- most common; also 45,X/46,XX mosaicism, isochromosome Xq, ring X, etc.

Pathophysiology: Loss of one X chromosome leads to:

• SHOX gene haploinsufficiency (on pseudoautosomal region of X) causing short stature
• Gonadal dysgenesis (streak gonads) causing primary amenorrhea and infertility
• Lymphatic dysplasia causing webbed neck and peripheral edema in neonates

Classic features mnemonic:

• Short Stature
• Shield chest, Widely Spaced nipples
• Webbed neck (pterygium colli)
• Low posterior hairline
• Cubitus Valgus
• Coarctation of aorta
• Streak gonads (primary amenorrhea)
• Horseshoe kidney

Differentiating from Noonan syndrome: Noonan syndrome has normal karyotype (PTPN11 mutation), affects both males and females, and has pulmonary stenosis (not coarctation) as the cardiac defect.

\[\boxed{\text{Turner Syndrome (45,X)}}\]