Concurrence of fragile X syndrome and 47, XYY in an individual with a Prader‐Willi‐like phenotype

We report on a 34‐year‐old developmentally disabled man referred to our clinic for evaluation of possible Prader‐Willi syndrome on the basis of obesity and voracious appetite. Cytogenetic and molecular analysis revealed a 47, XYY karyotype and the presence of a trinucleotide repeat expansion resulting in fragile X syndrome. To our knowledge, this is the first report of concurrence of XYY and fragile X syndrome in the medical literature. Review of sex chromosome abnormalities associated with fragile X syndrome and phenotypic considerations are presented. © 2003 Wiley‐Liss, Inc.