Horseshoe kidney is associated with which syndrome?

• A. Turner syndrome
• B. Down syndrome
• C. Klinefelter syndrome
• D. Ehlers-Danlos syndrome

Answer: (A)

Horseshoe kidney occurs when the lower poles of the kidneys fuse during development, forming a single U-shaped organ. As the fused kidney tries to ascend from the pelvis to its normal position, it is often held down by the inferior mesenteric artery, so it ends up located lower than usual and takes on its characteristic shape.

This congenital positioning and fusion anomaly is classically seen with Turner syndrome (45,X), a chromosomal condition in which renal malformations, including horseshoe kidney, are more common than in the general population. So in a patient with Turner syndrome, finding a horseshoe kidney fits a well-known association. While other syndromes can have renal anomalies, Turner syndrome is the classic linkage clinicians look for with this particular kidney anomaly.