A Diagnosis of Maturity-onset Diabetes of the Young Type 5 Provides Clarity and Broadens Reproductive Options.

Maturity-onset diabetes of the young type 5 (MODY5) is a rare form of monogenic diabetes caused by variants and deletions of the HNF1B gene. It is associated with a range of features including cystic renal disease, urogenital anomalies, and neurodevelopmental delay. Pregnancies in the presence of HNF1B gene variants and deletions have a significant risk of adverse maternal and fetal outcomes. Accurate diagnosis allows for genetic counseling, individualized therapies, and reproductive testing options. We report the case of a woman who was recognized as having MODY5 in her first pregnancy. The fetus inherited the gene variant and developed renal tract anomalies incompatible with ex utero life. The woman underwent in vitro fertilization with preimplantation genetic testing for a monogenic disorder (preimplantation genetic testing for monogenic/single-gene defects) for her following pregnancy.