Genomic changes in gliomas detected using single nucleotide polymorphism array in formalin-fixed, paraffin-embedded...

Area of Science:

• Neuro-oncology
• Genomics
• Molecular Diagnostics

Background:

• Loss of heterozygosity (LOH) on chromosomes 1p and 19q is critical for oligodendroglioma (ODG) diagnosis, prognosis, and treatment.
• Current clinical assays for detecting these genomic alterations are limited in scope.

Purpose of the Study:

• To evaluate the utility of single nucleotide polymorphism (SNP) arrays for identifying genomic alterations in gliomas from formalin-fixed paraffin-embedded (FFPE) tissues.
• To compare SNP array results with standard short tandem repeat (STR) assays for 1p and 19q LOH detection.

Main Methods:

• DNA was extracted from FFPE tissues of 30 brain tumors (15 ODGs, 15 non-ODGs).
• Samples were analyzed using Illumina SNP arrays with 300,000 markers.
• SNP array results were compared against conventional STR assays for chromosomes 1p and 19q.

Main Results:

• Fifteen ODGs showed concordant LOH and deletion on both 1p and 19q by STR and SNP array.
• Ten non-ODGs had no 1p/19q LOH by STR; seven showed no abnormalities, and three had partial deletions by SNP array.
• Five non-ODG cases exhibited partial LOH or deletion by both methods, with no major discordance observed.

Conclusions:

• SNP arrays are feasible for assessing genomic changes in routine glioma FFPE specimens.
• SNP arrays offer advantages including whole-genome screening, detection of small deletions, and differentiation of deletion types.
• SNP array analysis holds significant potential as an accurate clinical diagnostic test for gliomas.