There are many natural "bruises", most of which are caused by genetic mutations in some cells of the body while in the mother's body.In a common genetic disease, the genes in cells throughout the body have the same mutation, but the gene mutation in the bruise is limited to a part of the body and is called "mosaic".In mosaics, sperm and egg genes are often not mutated, so it is said that bruises are not inherited.However, in exceptional cases, it may be inherited to the next generation, in which case similar skin symptoms develop throughout the body.

　This time, the research group is studying epidermis-melting nevus resulting from a mosaic of gene mutations in keratin 1 or keratin 10.In the families included, epidermal ichthyosis developed throughout the body in a father's offspring with epidermal nevus at 5% of body surface area.

　First, the child's disease was confirmed by genetic diagnosis, and it was confirmed that the same gene mutation was found in the bruise of the father.In order to predict the possibility that the gene mutation will be transmitted to the next child and cause symptoms, the proportion of sperms with the gene mutation was measured by a technique called next-generation sequencing.As a result, it was found that 3.9% of the sperm cells of the father had the mutation, and it was predicted that the disease would develop in the next child with the same probability.

　The study explains that it will enable detailed genetic counseling for parents with epidermal nevus and reduce their anxiety about the future.

Paper information: [Journal of Investigative Dermatology] A child with epidermolytic ichthyosis from a parent with epidermolytic nevus: risk evaluation of transmission from mosaic to germline