Distribution and Functional Consequences of Somatic MAP2K1 Variants in Affected Skin Associated with Bone Lesions in Melorheostosis.

Melorheostosis (Online Mendelian Inheritance in Man #155950) is a rare disease of benign bone overgrowth (Freyschmidt, 2001) (Supplementary Figure S1). We recently described somatic activating variants in MAP2K1 in affected bone as a cause of the disease in nearly 60% of our cohort (Kang et al., 2018). Mosaicism for the variant was also detected in some patients in the skin directly overlying the affected bone. However, unlike the proliferative changes seen in bone, the overlying skin is characterized by patchy erythematous lesions but no overgrowth (Jha et al., 2019).