Loss-of-function deletions in HNF1B triggering maturity-onset diabetes of the young, type 5 [MODY5; also known as renal cyst and diabetes syndrome (RCAD); OMIM 137920; Box 1] have also been reported to cause Müllerian phenotypes in two patients (Lindner et al., 1999). The gene discussed is HNF1B; the disease is renal cysts and diabetes syndrome.