fragile X syndrome refers to the pattern of abnormality caused by a defect in the X chromosome resulting in mental retardation, learning problems, and unusual physical characteristics.
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Fragile X syndrome refers to the abnormality of the X chromosome caused by a defective gene and associated with mild to severe mental retardation, particularly when the defective gene is passed from mother to child.
Fragile X syndrome is also spelled Fragile-X syndrome. Please see Fragile-X syndrome