title: Mosaic isochromosome 15q and maternal uniparental isodisomy for chromosome 15 in a patient with morbid obesity and variant PWS-like phenotype.
abstract: Angelman and Prader-Willi syndromes are reciprocal imprinting disorders caused by loss of maternally or paternally expressed genes, respectively, within 15q11.2-q13. Angelman syndrome (AS; OMIM 105830) is a neurodevelopmental disorder and is due to the loss of maternally expressed UBE3A gene. Prader-Willi syndrome (PWS; OMIM 176270) is a clinically distinct disorder caused by the loss of paternally expressed genes in the human chromosome region 15q11.2-q13. Recently published data strongly suggest a role for the paternally expressed small nucleolar RNA (snoRNA) cluster, SNORD116, in PWS etiology. Uniparental disomy (UPD) 15 is one of the important causes of PWS and AS. Interestingly, balanced and unbalanced chromosomal aberrations in the form of Robertsonian translocation, isochromosomes, supernumerary marker chromosomes and copy number variations have been strongly linked with the occurrence of UPD. Here we report on a very unique case with a mosaic isochromosome for the entire long arm of 15, that is, i(15)(q10), resulting in mosaic uniparental isodisomy for 15q and with no copy number alterations. This is the first report of UPD15 constituted by a mosaic, but copy number neutral chromosomal rearrangement in a patient with a variant PWS-like phenotype.
authors.affiliation: Cytogenetics Laboratory, Quest Diagnostics Nichols Institute, San Juan Capistrano, CA 92690, USA.
authors.forename: Jia-Chi
authors.initials: JC
authors.lastname: Wang
authors.forename: Mary
authors.initials: M
authors.lastname: Vaccarello-Cruz
authors.forename: Leslie
authors.initials: L
authors.lastname: Ross
authors.forename: Renius
authors.initials: R
authors.lastname: Owen
authors.forename: Victoria M
authors.initials: VM
authors.lastname: Pratt
authors.forename: Katherine
authors.initials: K
authors.lastname: Lightman
authors.forename: Yan
authors.initials: Y
authors.lastname: Liu
authors.forename: Katayoun
authors.initials: K
authors.lastname: Hafezi
authors.forename: Dhia
authors.initials: D
authors.lastname: Cherif
authors.forename: Trilochan
authors.initials: T
authors.lastname: Sahoo
mesh_terms: D000293:Adolescent; D002884:Chromosomes, Human, Pair 15; D005260:Female; D015870:Gene Expression; D006801:Humans; D017404:In Situ Hybridization, Fluorescence; D018404:Isochromosomes; D009767:Obesity, Morbid / Q000235:genetics*; D020411:Oligonucleotide Array Sequence Analysis; D010641:Phenotype; D020641:Polymorphism, Single Nucleotide; D011218:Prader-Willi Syndrome / Q000235:genetics*; D024182:Uniparental Disomy; D055517:snRNP Core Proteins / Q000235:genetics
chemical_list: C526417:SNRPN protein, human; D055517:snRNP Core Proteins