6q16 microdeletion syndrome

6q16 microdeletion syndrome (Orphanet code 171829) is a rare chromosomal disorder caused by a submicroscopic deletion on the long arm of chromosome 6 in the region 6q16. This contiguous gene deletion syndrome affects multiple body systems, most prominently the central nervous system. Because the deletion removes several genes simultaneously, the clinical presentation can vary depending on the exact size and location of the deleted segment. Key clinical features include intellectual disability (ranging from mild to severe), developmental delay, obesity or a tendency toward excessive weight gain (often with early onset, sometimes resembling a Prader-Willi-like phenotype), hypotonia (low muscle tone), seizures, and behavioral abnormalities. Affected individuals may also present with distinctive facial features such as a broad forehead, epicanthal folds, a flat nasal bridge, and a thin upper lip. Some patients exhibit eye abnormalities and feeding difficulties in infancy. The SIM1 gene, located within the 6q16 region, is considered a critical gene for the obesity phenotype, as it plays a role in hypothalamic development and energy homeostasis. There is currently no cure for 6q16 microdeletion syndrome. Management is supportive and multidisciplinary, focusing on early intervention programs for developmental delay, speech and occupational therapy, seizure management with antiepileptic medications when needed, and dietary and behavioral strategies to address obesity. Regular monitoring by a team including neurologists, endocrinologists, and developmental pediatricians is recommended. Genetic counseling is advised for affected families.

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