D Kotzot1. 1. Institut für Humangenetik, Technische Universität München, Trogerstrasse 32, D-81675 München, Germany. DieterKotzot@gmx.de
Abstract
OBJECTIVE: To review all cases with segmental and/or complex uniparental disomy (UPD), to study aetiology and mechanisms of formation, and to draw conclusions. DESIGN: Searching published reports in Medline. RESULTS: The survey found at least nine cases with segmental UPD and a normal karyotype, 22 cases with UPD of a whole chromosome and a simple or a non-homologous Robertsonian translocation, eight cases with UPD and two isochromosomes, one of the short arm and one of the long arm of a non-acrocentric chromosome, 39 cases with UPD and an isochromosome of the long arm of two homologous acrocentric chromosomes, one case of UPD and an isochromosome 8 associated with a homozygous del(8)(p23.3pter), and 21 cases with UPD of a whole or parts of a chromosome associated with a complex karyotype. Segmental UPD is formed by somatic recombination (isodisomy) or by trisomy rescue. In the latter mechanism, a meiosis I error is associated with meiotic recombination and an additional somatic exchange between two non-uniparental chromatids. Subsequently, the chromatid that originated from the disomic gamete is lost (iso- and heterodisomy). In cases of UPD associated with one isochromosome of the short arm and one isochromosome of the long arm of a non-acrocentric chromosome and in cases of UPD associated with a true isochromosome of an acrocentric chromosome, mitotic complementation is assumed. This term describes the formation by misdivision at the centromere during an early mitosis of a monosomic zygote. In cases of UPD associated with an additional marker chromosome, either mitotic formation of the marker chromosome in a trisomic zygote or fertilisation of a gamete with a marker chromosome formed in meiosis by a disomic gamete or by a normal gamete and subsequent duplication are possible. CONCLUSIONS: Research in the field of segmental and/or complex UPD may help to explain undiagnosed non-Mendelian disorders, to recognise hotspots for meiotic and mitotic recombinations, and to show that chromosomal segregation is more complex than previously thought. It may also be helpful to map autosomal recessively inherited genes, genes/regions of genomic imprinting, and dysmorphic phenotypes. Last but not least it would improve genetic counselling.
OBJECTIVE: To review all cases with segmental and/or complex uniparental disomy (UPD), to study aetiology and mechanisms of formation, and to draw conclusions. DESIGN: Searching published reports in Medline. RESULTS: The survey found at least nine cases with segmental UPD and a normal karyotype, 22 cases with UPD of a whole chromosome and a simple or a non-homologous Robertsonian translocation, eight cases with UPD and two isochromosomes, one of the short arm and one of the long arm of a non-acrocentric chromosome, 39 cases with UPD and an isochromosome of the long arm of two homologous acrocentric chromosomes, one case of UPD and an isochromosome 8 associated with a homozygous del(8)(p23.3pter), and 21 cases with UPD of a whole or parts of a chromosome associated with a complex karyotype. Segmental UPD is formed by somatic recombination (isodisomy) or by trisomy rescue. In the latter mechanism, a meiosis I error is associated with meiotic recombination and an additional somatic exchange between two non-uniparental chromatids. Subsequently, the chromatid that originated from the disomic gamete is lost (iso- and heterodisomy). In cases of UPD associated with one isochromosome of the short arm and one isochromosome of the long arm of a non-acrocentric chromosome and in cases of UPD associated with a true isochromosome of an acrocentric chromosome, mitotic complementation is assumed. This term describes the formation by misdivision at the centromere during an early mitosis of a monosomic zygote. In cases of UPD associated with an additional marker chromosome, either mitotic formation of the marker chromosome in a trisomic zygote or fertilisation of a gamete with a marker chromosome formed in meiosis by a disomic gamete or by a normal gamete and subsequent duplication are possible. CONCLUSIONS: Research in the field of segmental and/or complex UPD may help to explain undiagnosed non-Mendelian disorders, to recognise hotspots for meiotic and mitotic recombinations, and to show that chromosomal segregation is more complex than previously thought. It may also be helpful to map autosomal recessively inherited genes, genes/regions of genomic imprinting, and dysmorphic phenotypes. Last but not least it would improve genetic counselling.
Authors: R P Spiro; S L Christian; D H Ledbetter; M I New; R C Wilson; N Roizen; R L Rosenfield Journal: Pediatr Res Date: 1999-11 Impact factor: 3.756
Authors: D Kotzot; D Balmer; A Baumer; K Chrzanowska; B C Hamel; H Ilyina; M Krajewska-Walasek; I W Lurie; B J Otten; E Schoenle; G Tariverdian; A Schinzel Journal: Eur J Pediatr Date: 2000-04 Impact factor: 3.183
Authors: S Das; C M Lese; M Song; J L Jensen; L A Wells; B L Barnoski; J A Roseberry; J M Camacho; D H Ledbetter; R E Schnur Journal: Am J Hum Genet Date: 2000-10-18 Impact factor: 11.025
Authors: Lukasz P Gondek; Ramon Tiu; Christine L O'Keefe; Mikkael A Sekeres; Karl S Theil; Jaroslaw P Maciejewski Journal: Blood Date: 2007-10-22 Impact factor: 22.113
Authors: Norihiko Kawamata; Seishi Ogawa; Martin Zimmermann; Motohiro Kato; Masashi Sanada; Kari Hemminki; Go Yamatomo; Yasuhito Nannya; Rolf Koehler; Thomas Flohr; Carl W Miller; Jochen Harbott; Wolf-Dieter Ludwig; Martin Stanulla; Martin Schrappe; Claus R Bartram; H Phillip Koeffler Journal: Blood Date: 2007-09-21 Impact factor: 22.113