An increased susceptibility to infections during childhood has also been reported. Etiology Tetrasomy X is generally thought to arise as a result of successive maternal nondisjunction during meiosis. [orpha.net]

An informal study of twenty girls with tetrasomy and pentasomy X found that 10 percent of patients had joint laxity in the hips, while 20 percent had joint limitations. [ clarification needed ] [ citation needed ] Developmentally, people with tetrasomy [en.wikipedia.org]

Many also show joint and muscle tone abnormalities, including hypotonia and joint looseness in the hips. Skeletal problems may also be present, including abnormal curvatures of the spine. [en.wikipedia.org]