Figure 1. Schematic representation of postzygotic mechanisms that may give rise to revertant mosaicism in an individual compound heterozygous for an autosomal recessive phenotype.

Two corresponding chromosomes carry either the paternal (blue) or maternal (pink) mutation. Various mutational events may result in cells showing loss of compound heterozygosity (bottom row). As a consequence, these cells will produce either a functional protein (black boxes), a semifunctional protein (gray box), or no protein at all (white boxes). Reproduced with permission from the American Journal of Medical Genetics (19).