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

Step 1: Identify the classic triad of features.

• Webbed neck (pterygium colli): Excess skin folds on the lateral neck
• Short stature: Growth failure due to haploinsufficiency of SHOX gene on X chromosome
• Low posterior hairline: Hair extends down low on the back of the neck

This triad is the hallmark of Turner syndrome.

Step 2: Review Turner syndrome. Turner syndrome is a chromosomal disorder in females caused by complete or partial monosomy of the X chromosome (45,X is the most common karyotype). Clinical features include:

• Webbed neck, low posterior hairline
• Short stature (SHOX gene haploinsufficiency)
• Shield chest with widely spaced nipples
• Cubitus valgus
• Primary amenorrhea and infertility (streak gonads)
• Coarctation of the aorta (most common cardiac defect)
• Horseshoe kidney (most common renal defect)
• Congenital lymphedema of hands and feet in neonates
• Normal intelligence (usually)

Step 3: Differentiate from other syndromes.

• Down syndrome (Trisomy 21): Flat facies, upslanting palpebral fissures, single palmar crease, intellectual disability -- no webbed neck or low hairline.
• Patau syndrome (Trisomy 13): Holoprosencephaly, cleft lip/palate, polydactyly -- severe malformations, not webbed neck.
• Edwards syndrome (Trisomy 18): Clenched fists, rocker-bottom feet, prominent occiput -- not webbed neck or low hairline.

Note: Webbed neck with similar features also appears in Noonan syndrome (normal karyotype), but Turner syndrome is the classic answer for this triad.

Conclusion: Webbed neck + short stature + low posterior hairline = Turner syndrome (45,X).