Phenotypically concordant and discordant monozygotic twins display different DNA copy number variation profiles (BAC)

The exploration of copy number variation (CNV), notably of somatic cells, is an understudied aspect of genome biology. Any differences in the genetic make-up between twins derived from the same zygote represent an extreme example of somatic variation. We studied 19 pairs of monozygotic twins with either concordant or discordant phenotype using two platforms for genome-wide CNV analyses and show that CNVs exist within pairs in both groups. These findings impact our views of genotypic and phenotypic diversity in monozygotic twins, and suggest that CNV analysis in phenotypically discordant monozygotic twins may provide a powerful tool in identifying disease predisposition loci. Our results also imply that caution should be exercised with the interpretation of disease causality of de novo CNVs found in patients based on analysis of a single tissue in routine disease-related DNA diagnostics Keywords: copy number variation, concordant and discordant monozygotic twins Analysis of copy number variability in monozygotic twin pairs discordant for a Parkinsons disease (PD) phenotype. One twin sibling was compared to the other. Dye swap repetitions are made for all PD twin comparisons, except for 1961vs1962, where a normal replicate is made instead. Three twin pairs have been compared to a healthy female subject (F1), with a regular and a dye swaped experiment. 292cy5_F1_cy3 and 702_cy5_F1_c3 have been repeated twice. In total, 32 hybridizations are made.