down syndrome
131XXXXX syndrome — A chromosomal disorder that affects females only, caused by the presence of five X chromosomes rather than the normal two. It is characterized by mild to severe mental retardation in most cases, sometimes by physical abnormalities, facial… …
132Down's syndrome — Also known as mongolism, most frequently a consequence of trisomy of chromosome 21. Common (1 in 700 live births) ; incidence increases with maternal age. The cause is usually non disjunction at meiosis but occasionally a translocation of fused… …
