VARIATION OF EXPRESSION OF THE GENE FOR TYPE-2 NEUROFIBROMATOSIS - ABSENCE OF A GENDER EFFECT ON VESTIBULAR SCHWANNOMAS, BUT CONFIRMATION OF A PREPONDERANCE OF MENINGIOMAS IN FEMALES

Type 2 neurofibromatosis is a dominantly inherited disorder in which t he great majority of sufferers develop bilateral vestibular schwannoma s. In a UK study of 183 individuals from 112 families we have previous ly shown a fairly similar disease course within families, but quite ma rked inter-familial variation. We have confirmed an increase in severi ty when the gene is inherited from an affected mother, but evidence th at women are more severely affected than men is lacking. Age at onset of symptoms, of deafness and at diagnosis are identical for the entire dataset and for a comparison of 10 male/female sibling pairs. Only th ree out of 42 pregnancies in symptomatic women were accompanied by a r eversible worsening in symptoms due to vestibular schwannomas. Of 328 consecutive cases of unilateral vestibular schwannoma, there was no si gnificant difference in the sex ratio or size. There now appears to be little evidence for a female hormonal effect on vestibular schwannoma s. However, females with type 2 neurofibromatosis have sigificantly mo re meningiomas.