Functional disomy of proximal Xp causes a distinct phenotype comprising early hypotonia, hypertelorism, small hands and feet, ear abnormalities, myopia and cognitive impairment.
Extra structurally abnormal chromosomes (ESACs) derived from the X chromosome are rare. We report a non-mosaic ESAC derived from the X chromosome in a 3-year-old female who presented with early hypotonia, developmental delay, hypertelorism, low set ears, and small hands and feet. The breakpoints of the ESAC were mapped by SNP microarray to Xp11.1-p11.22, a region encompassing 7.17 Mb and containing 110 known or putative genes and excluding the X-inactivation center. A review of other reported patients with karyotypes that cause functional disomy of proximal Xp allows delineation of a common phenotype comprising early hypotonia, cognitive impairment, hypertelorism, myopia, small hands and feet and abnormal external ears.
Hunter
Matthew
M
Royal Children's Hospital, Melbourne, Australia.
Bruno
Damien
D
Amor
David J
DJ
D000015:Abnormalities, Multiple / Q000235:genetics*; D002675:Child, Preschool; D041321:Chromosomes, Human, X / Q000235:genetics*; D004423:Ear / Q000002:abnormalities; D005260:Female; D006801:Humans; D006972:Hypertelorism / Q000150:complications / Q000235:genetics*; D008607:Intellectual Disability / Q000150:complications / Q000235:genetics*; D007621:Karyotyping; D017880:Limb Deformities, Congenital / Q000150:complications / Q000235:genetics*; D009123:Muscle Hypotonia / Q000150:complications / Q000235:genetics*; D009216:Myopia / Q000150:complications / Q000235:genetics; D010641:Phenotype; D024182:Uniparental Disomy / Q000235:genetics*