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 the great majority of sufferers develop bilateral vestibular schwannomas. In a UK study of 183 individuals from 112 families we have previously shown a fairly similar disease course within families, but quite marked inter-familial variation. We have confirmed an increase in severity when the gene is inherited from an affected mother, but evidence that 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 three out of 42 pregnancies in symptomatic women were accompanied by a reversible worsening in symptoms due to vestibular schwannomas. Of 328 consecutive cases of unilateral vestibular schwannoma, there was no significant difference in the sex ratio or size. There now appears to be little evidence for a female hormonal effect on vestibular schwannomas. However, females with type 2 neurofibromatosis have significantly more meningiomas.