Figure 2. Possible mechanisms of generating hyperhaploidy.

1. Cells undergo genome-wide loss of chromosomes resulting in haploidy (n=1) followed by subsequent duplication of some chromosomes (n=1.4), resulting in loss of heterozygosity (LOH) on all chromosomes. 2. Cells first become hyperdiploid (n=2.4) before losing a haploid genome (n=1.4). In this instance paternal or maternal chromosomes are lost randomly resulting in diploid chromosomes with LOH 33% of the time. 3. Cells undergo loss of chromosomes resulting in hyperhaploid state (n=1.4) with retention of heterodisomy in all diploid chromosomes, which is consistent with our results.