Molecular genetic analysis of the mechanism of tumorigenesis in acoustic neuroma.

OBJECTIVE

Acoustic neuroma, both familial and sporadic, is clinically and biologically a heterogeneous condition with a wide variation in age of presentation, length of history, and tumor growth rate. In an attempt to correlate this clinical diversity with the underlying molecular pathology, we have analyzed 43 paired blood-tumor DNA samples from patients with acoustic neuromas.

DESIGN

Molecular genetic analysis.

SETTING

Molecular genetic research laboratory.

PATIENTS

Paired blood-tumor DNA samples were obtained from 43 patients (41 sporadic and two patients with neurofibromatosis type 2).

MAIN OUTCOME MEASURES

Loss of constitutional heterozygosity was looked for in the region of tumor suppressor genes on chromosomes 3p, 5q, 11p, 17p, 17q, and 22.

RESULTS

We found loss of heterozygosity exclusively for markers on chromosome 22. Thirty-nine percent of tumors showed allele loss, and in each case the loss of heterozygosity included the region of the neurofibromatosis type 2 (NF2) gene. No loss of heterozygosity was detected in the region of known or putative suppressor genes in chromosomes 3p, 5q, 11p, 17p, and 17q.

CONCLUSIONS

This study has demonstrated that (1) chromosome 22 allele loss is a frequent event in sporadic acoustic neuroma; (2) the minimal region of loss of heterozygosity in acoustic neuroma includes the NF2 gene; (3) the known tumor suppressor genes investigated (VHL, adenomatous polyposis coli, WT2, p53, and NF1) do not appear to be important in the pathogenesis of acoustic neuroma; and (4) patients with extensive chromosome 22 loss tended to be younger and with a slightly shorter clinical history than those with no detectable allele loss.