A phenotypic female with 49 chromosomes, presumably XXXXX

A 2-year-old girl is presented whose cultured peripheral blood consistently hasprovided metaphase cells with 49 chromosomes. She is physically and behaviorally retarded and was born with patent ductus arteriosus which has been ligated. Minor stigmas of facies, irises, and extremities are described. On the basis of chromosome morphology, the presence of a significant number of buccal epithelial cells with 4 chromatin bodies, and the asynchronous segregation of 4 chromosomes in Group C as determined by uptake of tritiated thymidine, it is concluded that the extra chromosomes are of the X type. This aneuploid pattern has probably resulted from nondysjunction during both meiotic phases of ovular maturation and subsequent fertilization by an X-bearing sperm. It has been suggested that this be termed the penta X constitution pending description of other individuals with a similar chromosome pattern.