2p21 microdeletion syndrome

2p21 microdeletion syndrome (also known as cystinuria-hypotonia-intellectual disability syndrome or hypotonia-cystinuria syndrome) is a rare chromosomal disorder caused by a contiguous gene deletion on the short arm of chromosome 2 at band p21. The deletion typically encompasses several genes, most notably SLC3A1 (associated with cystinuria) and PREPL (associated with hypotonia and neurodevelopmental features). The size of the deletion can vary among affected individuals, which influences the range and severity of symptoms. The syndrome primarily affects the nervous system, kidneys, and musculoskeletal system. Key clinical features include neonatal or infantile hypotonia (low muscle tone), feeding difficulties in early life, intellectual disability of variable severity, growth retardation, and cystinuria — a condition in which excessive amounts of the amino acid cystine are excreted in the urine, predisposing individuals to recurrent kidney stones. Some patients may also exhibit facial dysmorphism, obesity in later childhood, and speech and motor developmental delays. Management of 2p21 microdeletion syndrome is symptomatic and supportive. Treatment of cystinuria involves high fluid intake, urinary alkalinization, and sometimes medications such as tiopronin or D-penicillamine to reduce cystine stone formation. Hypotonia and developmental delays are addressed through early intervention programs including physical therapy, occupational therapy, and speech therapy. There is currently no cure for this condition, and long-term follow-up with a multidisciplinary team including nephrologists, neurologists, and developmental specialists is recommended.

Common questions about 2p21 microdeletion syndrome