Distal monosomy 7q36 syndrome

Distal monosomy 7q36 syndrome (also known as terminal deletion 7q36 or distal 7q deletion) is a rare chromosomal disorder caused by a partial deletion of the long arm of chromosome 7, specifically involving the 7q36 region. This deletion leads to the loss of several genes critical for normal development, most notably the SHH (Sonic Hedgehog) gene, which plays a fundamental role in embryonic patterning and limb development. The syndrome primarily affects the central nervous system, craniofacial structures, and limbs. Key clinical features include holoprosencephaly (a failure of the forebrain to properly divide into two hemispheres), which can range from mild to severe forms, and sacral agenesis or caudal regression anomalies. Craniofacial abnormalities may include cyclopia, midface hypoplasia, cleft lip and/or palate, and microcephaly. Limb malformations, particularly preaxial polydactyly or other digital anomalies, are frequently observed. Intellectual disability and developmental delay of variable severity are common. Growth retardation and various organ malformations may also be present. There is no cure for distal monosomy 7q36 syndrome. Management is supportive and symptomatic, tailored to the specific manifestations in each individual. This may include surgical correction of craniofacial or limb anomalies, neurodevelopmental support, physical and occupational therapy, and management of associated organ malformations. A multidisciplinary team approach involving geneticists, neurologists, surgeons, and developmental specialists is typically required. Prognosis varies widely depending on the size of the deletion and the severity of associated malformations, particularly the degree of holoprosencephaly.

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