Mosaicism denotes an individual who has at least two populations of cells with distinct
genotypes that are derived from a single fertilized egg. Genetic variation among the cell
lines can involve whole chromosomes, structural or copy-number variants, small or single-
nucleotide variants, or epigenetic variants. The mutational events that underlie mosaic
variants occur during mitotic cell divisions after fertilization and zygote formation. The
initiating mutational event can occur in any types of cell at any time in development, leading …