This information is provided by the National Institutes of Health (NIH) Genetic and Rare Diseases Information Center (GARD).
48,XXXY syndrome is a type of chromosome abnormality characterized by the presence of 2 extra X chromosomes in males. It is sometimes referred to as a variant of Klinefelter syndrome, but differs from Klinefelter syndrome in many ways and is more severe. Signs and symptoms of 48,XXXY syndrome can vary but may include learning difficulties; intellectual disability; low muscle tone (hypotonia); hypogonadism; delayed growth; distinctive facial features; and a variety of birth defects that may affect the genital and musculoskeletal systems. Many also have poorly developed social skills and delayed language development. This condition is not inherited and likely results from a random error in cell division. Treatment depends on the features in each individual and often involves the coordinated efforts of a multidisciplinary team of specialists.
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