title: Pigmentary mosaicism in hypomelanosis of Ito. Further evidence for functional disomy of Xp.
abstract: We report on a female with mental and motor retardation, facial dysmorphism, abnormal pigmentation reminiscent to hypomelanosis of Ito (HI), and karyotypic mosaicism involving a small supernumerary marker chromosome. The marker chromosome was defined by fluorescence in situ hybridisation (FISH) as a ring X chromosome with breakpoints in the juxtacentromeric region. FISH analysis showed that the ring does not include the XIST locus at the X-inactivation centre and, therefore, may not be subject to X inactivation. X-inactivation studies with the HUMARA (human androgen receptor) and FMR1 assay showed a skewed X-inactivation pattern (85:15) with preferential inactivation of the paternal X chromosome. These results are discussed with respect to the role of functional disomy of Xp in the pathogenesis of HI.
authors.affiliation: Department of Clinical Genetics, Medical Center of Human Genetics, Philipps University Marburg, Germany. fritzb@mailer.uni-marburg.de
authors.forename: B
authors.initials: B
authors.lastname: Fritz
authors.forename: W
authors.initials: W
authors.lastname: Küster
authors.forename: K H
authors.initials: KH
authors.lastname: Orstavik
authors.forename: A
authors.initials: A
authors.lastname: Naumova
authors.forename: J
authors.initials: J
authors.lastname: Spranger
authors.forename: H
authors.initials: H
authors.lastname: Rehder
mesh_terms: D002675:Child, Preschool; D004303:Dosage Compensation, Genetic; D005260:Female; D006801:Humans; D017404:In Situ Hybridization, Fluorescence; D007621:Karyotyping; D009030:Mosaicism; D010859:Pigmentation Disorders / Q000235:genetics*; D012303:Ring Chromosomes; D014960:X Chromosome