Abstract
Neurofibromatosis (NF) is a serious, common, genetically determined neurological disorder; with a prevalence of about 1:4000 births it affects both sexes and all races and ethnic groups. The two major forms are referred to as NF1 and NF2, as suggested in 1987 by a National Institutes of Health Consensus Development Conference on Neurofibromatosis. In NF1, the disease phenotype is more variable and complex than in NF2. Complications can occur in any of the body systems in tissues of ectodermal, mesodermal and neural tube origin; there is marked variation of disease phenotype even within families. The NF2 gene, in contrast, only seems to be expressed in tissues of ectodermal origin and its expression is more uniform both within and between families. The recent discovery and isolation of the gene responsible for the NF1 mutation has practical applications in the field of molecular genetics which could modify the approaches for diagnosis, treatment and prevention of NF. This Memorandum summarizes the discussions and recommendations of the participants at a joint WHO/National Neurofibromatosis Foundation (NNFF) meeting, held in Jacksonville, Florida, USA, on 27-28 January 1991.