This information is provided by the National Institutes of Health (NIH) Genetic and Rare Diseases Information Center (GARD).
Linear nevus sebaceous syndrome (LNSS) is a condition characterized by the association of a large, linear sebaceous nevus (type of birthmark) with a broad range of abnormalities that may affect every organ system, including the central nervous system (CNS).[12881] The nevus usually is located on the face, scalp, or neck.[12881][12883] The most common CNS abnormalities are intellectual disability, seizures, and hemimegalencephaly (abnormal enlargement of one side of the brain).[12881][12883] Various other CNS abnormalities have been reported.[12883] Other signs and symptoms may include various eye abnormalities; skeletal (bone) deformities; heart defects; urogenital abnormalities; and an increased risk of cancer with age.[12881][3954][3955] LNSS is not inherited (it is sporadic). It can be caused by a somatic mutation in any of several genes. Mutations that cause LNSS occur after fertilization and are only present in some body cells (mosaicism).[12887] Treatment is directed towards the specific symptoms in each person.[12884]
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