Fig. 1

An illustration of the genotype data used for phasing. The DNA of the proband consists of two haploid genotypes across all chromosomes. IBD segments also consist of two haplotypes, one of which is identical to one of the proband’s haplotypes. Note that each IBD segment (partial diploid) is consistent with exactly one of the proband’s haplotypes, and that we can infer that the same haplotype in the proband is shared with individual A and individual B, even though those segments do not overlap (because they both overlap with individual C). Individual C’s two IBD segments are on different chromosomes and it is more likely than not that the haplotypes shared with individual C are inherited from the same parent (with dozens or hundreds of multi-chromosome IBD segments, inter-chromosome phasing becomes clearer)