17q12 microdeletion syndrome

17q12 microdeletion syndrome (also known as 17q12 deletion syndrome or chromosome 17q12 deletion syndrome) is a rare genetic condition caused by a small deletion of genetic material on the long arm of chromosome 17, typically spanning approximately 1.4 megabases and encompassing several genes, most notably HNF1B (also called TCF2). This contiguous gene deletion syndrome affects multiple body systems, with the kidneys and urinary tract being the most consistently involved. The hallmark renal feature is cystic kidney disease, often presenting as multicystic dysplastic kidneys or other renal structural anomalies, which may be detected prenatally on ultrasound. Maturity-onset diabetes of the young type 5 (MODY5) is another key feature, typically developing in adolescence or early adulthood due to the loss of the HNF1B gene, which plays a critical role in pancreatic development and function. Neurodevelopmental features are increasingly recognized as an important component of this syndrome. Many affected individuals exhibit developmental delay, learning difficulties, autism spectrum disorder, or other behavioral and psychiatric conditions, including schizophrenia. Cognitive abilities range from normal intelligence to mild or moderate intellectual disability. Additional features may include liver abnormalities, genital tract malformations (particularly Müllerian duct anomalies in females such as uterine and vaginal abnormalities), hyperuricemia, and hypomagnesemia. The clinical presentation is highly variable, even among members of the same family, and some individuals may be only mildly affected. There is currently no cure for 17q12 microdeletion syndrome, and management is supportive and symptom-based. Treatment may include monitoring and management of renal function, insulin or oral hypoglycemic agents for diabetes, educational support and behavioral interventions for neurodevelopmental concerns, and surgical correction of structural anomalies when necessary. Regular screening for diabetes and renal complications is recommended. Genetic counseling is important for affected individuals and their families, as the deletion may be inherited from a mildly affected parent or may occur de novo.

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