title: Large Autosomal Copy-Number Differences within Unselected Monozygotic Twin Pairs are Rare.
abstract: Monozygotic (MZ) twins form an important system for the study of biological plasticity in humans. While MZ twins are generally considered to be genetically identical, a number of studies have emerged that have demonstrated copy-number differences within a twin pair, particularly in those discordant for disease. The rate of autosomal copy-number variation (CNV) discordance within MZ twin pairs was investigated using a population sample of 376 twin pairs genotyped on Illumina Human610-Quad arrays. After CNV calling using both QuantiSNP and PennCNV followed by manual annotation, only a single CNV difference was observed within the MZ twin pairs, being a 130 KB duplication of chromosome 5. Five other potential discordant CNV were called by the software, but excluded based on manual annotation of the regions. It is concluded that large CNV discordance is rare within MZ twin pairs, indicating that any CNV difference found within phenotypically discordant MZ twin pairs has a high probability of containing the causal gene(s) involved.
authors.affiliation: Queensland Brain Institute,The University of Queensland,Brisbane,Queensland,Australia.
authors.forename: Allan F
authors.initials: AF
authors.lastname: McRae
authors.affiliation: Queensland Brain Institute,The University of Queensland,Brisbane,Queensland,Australia.
authors.forename: Peter M
authors.initials: PM
authors.lastname: Visscher
authors.affiliation: QIMR Berghofer Medical Research Institute,Brisbane,Queensland,Australia.
authors.forename: Grant W
authors.initials: GW
authors.lastname: Montgomery
authors.affiliation: QIMR Berghofer Medical Research Institute,Brisbane,Queensland,Australia.
authors.forename: Nicholas G
authors.initials: NG
authors.lastname: Martin
mesh_terms: D001315:Australia; D002877:Chromosomes, Human / Q000235:genetics*; D056915:DNA Copy Number Variations; D005260:Female; D006801:Humans; D008297:Male; D020411:Oligonucleotide Array Sequence Analysis; D020641:Polymorphism, Single Nucleotide; D014430:Twins, Monozygotic / Q000235:genetics*
keywords: post-zygotic