Nail-Patella Syndrome LMX1B — ESENeph MCQ

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HardGlomerulonephritisNail-Patella Syndrome LMX1BESENeph

A 40-year-old woman presents with CKD and a kidney biopsy showing nail-patella-like changes: irregular thickening of the GBM with moth-eaten appearance on EM. She has dysplastic fingernails and absent patellae. What gene is mutated?

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Correct answer: C — LMX1B – a transcription factor essential for limb and kidney development; mutations cause nail-patella syndrome (hereditary osteo-onychodysplasia)

Nail-patella syndrome (hereditary osteo-onychodysplasia) is caused by heterozygous mutations in LMX1B, a LIM homeodomain transcription factor essential for limb, kidney, and eye development. Renal manifestations occur in 30-50% of patients and range from proteinuria to ESKD. The characteristic GBM finding on EM is irregular thickening with a moth-eaten/lucent appearance from collagen fibril disorganisation. The classic tetrad is: nail dysplasia, absent/hypoplastic patellae, iliac horns on X-ray, and nephropathy. Treatment is supportive (RASi for proteinuria, standard CKD care).

Reference: Sweeney et al 2003 – Nail-Patella Syndrome; KDIGO 2021 – GN