Mosaic neurofibromatosis type 1

Definition

A rare mosaic form of neurofibromatosis type 1 (NF1) characterized by findings typical of NF1, namely multiple café-au-lait macules (CALMs), cutaneous neurofibromas, skinfold freckling/lentiginous macules, iris Lisch nodules and tumors of the nervous system. Mosaic form is caused by postzygotic pathogenic variants in NF1-gene. In mosaic NF1 the allelic/tissue distribution of the pathogenic NF1-variant clearly suggests mosaicsm and/or the distribution of CALMs and cutaneous neurofibromas is segmental. The phenotype can be milder than in NF1.