A Unique Case of Joubert Syndrome with Concurrent IgA Nephropathy and Nephronophthisis in an Adult Patient

A 30-year-old male born from a consanguineous marriage, with intellectual disability, developmental delay and Type 1 diabetes presented with polyuria and uremic symptoms. Physical examination revealed hypertension, retinitis pigmentosa, bilateral rotatory grade 3 nystagmus, eyelid droop, truncal obesity, acanthosis nigricans, and muscle hypotonia. Laboratory tests indicated kidney dysfunction. Magnetic resonance imaging of the brain showed the "molar tooth sign," a hallmark of Joubert syndrome. The kidney biopsy highlighted features of IgA nephropathy, diabetic nephropathy, and nephronophthisis. Whole exome sequencing identified a homozygous nonsense variant in the AHI1 gene, known to cause Joubert syndrome 3. This case is unique due to its genetic proof of an AHI1 mutation causing Joubert syndrome in an Indian patient and the co-occurrence of IgA nephropathy with nephronophthisis.