Figure 3.

Schematic of hypothetical meiotic and mitotic recombination events leading to the observed allelic and copy number imbalances in the proband. (a) Shows a possible exchange between homologous chromosomes at meiosis that could lead to a copy number gain in two neighbouring genes (labelled G1 and G2); the coloured boxes represent flanking alleles of a repetitive sequence. (b) Shows the homologous chromosomes 3 of the proband at conception. (c) Shows a possible early mitotic event (between homologous copies of chromosome 3) during development of the proband that would give rise to interstitial segmental isodisomy in the region bounded by genes 1 and 2. The contribution of this cell line with that of the cell line represented in (b) would be consistent with the allelic imbalance and copy number data of the proband.