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Comprehensive Strategy IDs Mutation in Homologous Genes

Approach can accurately detect mutations in genes with multiple copies of highly homologous sequences

FRIDAY, Aug. 28, 2015 (HealthDay News) — A comprehensive approach can improve molecular analysis of PMS2 for patients with Lynch syndrome, according to a study published online Aug. 27 in the Journal of Molecular Diagnostics.

In an effort to establish a comprehensive approach for mutation detection of PMS2, Jianli Li, Ph.D., from Baylor Miraca Genetics Laboratories in Houston, and colleagues designed a strategy combining targeted capture next-generation sequencing (NGS), multiplex ligation-dependent probe amplification, and long-range polymerase chain reaction (PCR) followed by NGS.

The researchers identified exonic deletions, duplications, and a nonsense mutation, p.S22*. When PMS2 and PMS2CL shared identical sequences as a result of gene conversion, traditional multiplex ligation-dependent probe amplification and Sanger sequencing approaches were unable to differentiate the origin of the exonic deletions in the 3′ region. However, using of the combination strategy, the researchers were able to identify mutations in the active gene unambiguously with a straightforward long-range-PCR/NGS method. Recurrent exon 14 deletions were found to be mediated by homologous Alu sequences in breakpoint analysis of multiple samples.

“Our comprehensive approach provides a reliable tool for accurate molecular analysis of genes containing multiple copies of highly homologous sequences and should improve PMS2 molecular analysis for patients with Lynch syndrome,” the authors write.

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