Although mutations in HNF1β were first identified as a cause of maturity onset diabetes of youth, it has become increasingly clear over time that the predominant clinical manifestations of this condition involve the kidney. HNF1β is a master transcription factor regulating the expression of several kidney-specific genes from the first steps of nephrogenesis.
Thus, mutations in HNF1β can affect kidney development, maintenance of the tubular architecture, cyst formation, and ion transport. Mutations in HNF1β comprise whole-gene deletions, missense, non-sense, frameshift, and splice-site mutations with TILDE OPERATOR+D9150% of them occurring de novo.
The allelic heterogeneity is reflected by the varied clinical presentation, making diagnosis difficult. In this month's Kidney International Reports, Izzi and colleagues present a case series showing the many presentations of HNF1β mutations, including a newly described manifestation: medullary sponge kidney.