title: Hexasomy of the Prader-Willi/Angelman critical region, including the OCA2 gene, in a patient with pigmentary dysplasia: case report.
abstract: Derivatives of chromosome 15, often referred to as inv dup(15), represent the most common supernumerary marker chromosome (SMC). SMC(15)s can be classified into two major groups according to their length: small SMC(15) and large ones. Depending on the amount of euchromatin, the carriers may either present with a normal phenotype or with a recognizable syndrome. Here we describe a patient with severe mental retardation, epilepsy, dysmorphic features and pigmentary dysplasia. His karyotype was 47,XY,+mar[41]/46,XY[9]. Chromosomal fluorescence in situ hybridization (FISH) showed the SMC to be originating from chromosome 15, dicentric and containing four copies of the Prader-Willi/Angelman Syndrome Critical Region (PWACR), including the OCA2 gene. Molecular studies indicated that it is maternally derived. This report supports the previous observations assuming that severity of phenotype in patients with SMC(15) depends on the dosage of the PWACR and that skin pigmentation is correlated to OCA2 gene copy number.
authors.affiliation: Charles Nicolle Hospital, Department of Congenital and Hereditary Diseases, Tunis, Tunisia. Kraoua_lilia@yahoo.fr
authors.forename: Lilia
authors.initials: L
authors.lastname: Kraoua
authors.forename: Myriam
authors.initials: M
authors.lastname: Chaabouni
authors.forename: Elisabeth
authors.initials: E
authors.lastname: Ewers
authors.forename: Imen
authors.initials: I
authors.lastname: Chelly
authors.forename: Ines
authors.initials: I
authors.lastname: Ouertani
authors.forename: Lamia
authors.initials: L
authors.lastname: Ben Jemaa
authors.forename: Faouzi
authors.initials: F
authors.lastname: Maazoul
authors.forename: Thomas
authors.initials: T
authors.lastname: Liehr
authors.forename: Habiba
authors.initials: H
authors.lastname: Chaabouni
mesh_terms: D000293:Adolescent; D017204:Angelman Syndrome / Q000235:genetics*; D002871:Chromosome Banding; D025063:Chromosome Disorders / Q000235:genetics; D002884:Chromosomes, Human, Pair 15 / Q000235:genetics; D006801:Humans; D008297:Male; D026901:Membrane Transport Proteins / Q000235:genetics*; D010641:Phenotype; D010859:Pigmentation Disorders / Q000235:genetics*; D011218:Prader-Willi Syndrome / Q000235:genetics*
chemical_list: D026901:Membrane Transport Proteins; C489600:OCA2 protein, human