Overall, by studying the haplotype backgrounds, we deduced that the 63 deletions correspond to approximately 31 separate mutation/deletion events (Supplementary Results). A rather complex pattern of inheritance was indicated. Firstly, carriers of these deletions are not completely infertile and, moreover, could pass on the deletion to their children (one carrier with 5 children overall passed on the deletion to all 4 of the chip-typed children). However, the probability that the carriers could pass on the deletion to a child appears to be substantially lower than that under a model of neutrality. The many haplotype backgrounds observed for the chromosomes with the deletion indicate that the deletion occurs rather frequently as a de novo event. This is in sharp contrast to other rare variants such as the BRAC2 mutation in Iceland where all chromosomes with the mutation appear to have a single founder and share a haplotype background15,16. If the deletions were inherited neutrally, they would be expected to have a much higher frequency in the population than observed. Hence, this novel approach provides support to the notion that the deletions
