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. Author manuscript; available in PMC: 2021 Apr 7.
Published in final edited form as: Annu Rev Genet. 2017 Nov 27;51:123–141. doi: 10.1146/annurev-genet-121415-121955

Figure 2. Types of segmental mosaicism.

Figure 2.

Segmental mosaicism refers to the Blaschko-linear patterning of cutaneous lesions that respect the midline: Single postzygotic mutations leading to segmental lesions reflect type 1 segmental mosaicism, by which the mutation is limited to lesional tissue in an otherwise wild-type individual. Type 2 segmental mosaicism occurs when a second mutagenesis event, such as loss of heterozygosity, occurs in individuals already carrying heritable mutations, leading to segments with more severe phenotype.