Renal cysts in WDR72-associated distal renal tubular acidosis: expanding the phenotypic spectrum.

Pathogenic variants in the WDR72 gene are known to cause hypoplastic amelogenesis imperfecta (AI) and have recently been linked to distal renal tubular acidosis (dRTA). This case report highlights an unusual presentation of WDR72-associated dRTA with renal cysts. A 12-year-old boy presented with difficulty walking, lower limb deformities, and significant growth retardation. On examination, hypoplastic AI, rickets, and short stature were present. Biochemical investigations showed hypokalemia, hypophosphatemia, elevated alkaline phosphatase, and hypercalciuria. Imaging revealed medullary nephrocalcinosis and renal cysts. Clinical exome sequencing identified a homozygous pathogenic nonsense variant in WDR72 (NM_182758.4): c.2934G > A (p.Trp978Ter), consistent with autosomal recessive inheritance. He was diagnosed with dRTA and managed with potassium citrate and phosphate supplementation. Over two years, the patient showed improved growth velocity and reduced hypercalciuria, though nephrocalcinosis and renal cysts persisted. This case of WDR72-associated dRTA complicated by renal cyst formation is an underrecognized phenotype of this rare disorder. It further highlights that delayed diagnosis and prolonged, uncorrected tubulopathy may result in structural renal injury that is not fully reversible with treatment. Systematic renal evaluation, including biochemical assessment and renal ultrasonography, is strongly warranted in all children presenting with AI, particularly in the presence of concurrent growth failure, electrolyte disturbances, or rachitic changes, to facilitate early diagnosis and mitigate the risk of long-term renal sequelae.