Ile/Ile homozygosity at codon 655 of HER2 in schwannoma

This study aimed to determine the genetic role of HER2, one of the epidermal growth factor receptor (EGFR) family, in schwannoma. The latter is a neogrowth of myelin-producing Schwann cells in peripheral nerves, inducible by N-nitrosoethylurea in animals with mutation in the neu gene (homologous gene of human HER2 protein).

In this study we obtained genomic DNA samples from tissue blocks of schwannoma, initially by xylene treatment and alcohol extraction, followed by use of the DNA extraction kit. Evaluation of this genetic polymorphism in our subjects was conducted by direct nucleotide sequencing or restriction enzyme analyses after PCR work.

There were thirty extracted DNA samples from tissue blocks of schwannoma, and all were Ile/Ile homozygotes after genotype analyses. Two individuals received the leukocyte DNA extraction after peripheral blood sampling, both showing Ile/Ile homozygosity. This study gave the impression of an association of the HER2 polymorphism at codon 655 with tumorigenesis of schwannoma. Although the majority of the Taiwanese showed Ile/Ile homozygosity (about 83%), the present study revealed a 100% carriage rate among the tissue blocks from our subjects with schwannoma.

Ile/Ile homozygosity at codon 655 of HER2 in schwannoma may imply some role in tumorigenesis of Ile655Val allele of HER2 in this nerve tumor.