Possible maternal effect on severity of neurofibromatosis.

62 patients with neurofibromatosis (from 54 families) whose signs or symptoms began in childhood were assessed as to the severity of disease and whether the individual was a new mutation or born to an affected father or mother. The morbidity of disease was much more severe in cases born to affected mothers than in those born to affected fathers or those who were new mutations. This finding suggests that there may be a maternal effect in neurofibromatosis similar to that which has been observed in myotonic dystrophy. This effect may be humorally mediated.