In Silico Analysis of NF2 Gene Missense Mutations in Neurofibromatosis Type 2: From Genotype to Phenotype.

HYPOTHESIS

Computer-based (in silico) protein modeling to examine genotype-phenotype relationships for a given mutation has been applied to many genes but never to NF2.

BACKGROUND

Missense mutations in the merlin protein occur in approximately 9% of patients with neurofibromatosis type 2 (NF2). Within this subset of patients, no genotype-phenotype correlations have been established. The aim of this study was to determine if genotype correlates with phenotype in the cohort of NF2 patients with missense mutations as a first step to defining a method to predict clinical phenotype from genotype for these patients.

METHODS

We analyzed 45 patients with NF2 as a result of missense mutations drawn from the United Kingdom NF2 registry. Our analysis included 17 different NF2 mutations from NF2 patients and six single-nucleotide polymorphisms (SNP)--presumed benign because they are observed in the dbSNP National Center for Biotechnology Information database and 1000 Genomes. We analyzed the mutations using three mutation tolerance prediction approaches: Align GVGD, SIFT, and PolyPhen-2. The mutation sites were also modeled on the three-dimensional crystal structure of merlin to investigate the spatial relationship of NF2-causing mutations.

RESULTS

Two mutation tolerance predictors (SIFT and PolyPhen-2) were able to distinguish NF2-causing mutations from non-NF2-causing SNPs (p < 0.05). Mapping mutations on the molecular structure of merlin suggest that mutations resulting in greater structural conflicts within the protein are more likely to correlate with severe phenotypes.

CONCLUSION

This work is a step toward a better understanding of genotype-phenotype relationships in NF2 caused by missense mutations using a computer-based methodology.