Abstract
Purpose::
Published information on linkage mapping, mRNA expression, microarray data, known biological function or predicted biochemical pathways of candidate proteins were used to prioritize selected genes for screening at the GLC1B locus. We aimed to reduce the GLC1B region by family-based linkage analysis and to further screen the prioritized genes in a group of adult-onset POAG families.
Methods::
Highly polymorphic DNA markers and SNPs were used for saturation mapping of our potentially linked families. Sequence specific primers flanking the intron-exon boundaries were used for PCR-amplification and direct DNA sequencing of the prioritized genes.
Results::
The 2 extreme GLC1B boundaries as defined by D2S2161 and D2S410 contain over 220 genes, of which previously we excluded 20 of them. In this study, Bioinformatic, genomic convergence and proteomic streamlining methods prioritized 23 of these genes as the most promising candidates. We screened and excluded 5 new genes (TGOLN2, MAT2A, ST3GAL5, BCL2L11, NCK2) from this region. Our combined linkage information from British, French-Canadian, Peruvian and Australian POAG families suggests that the GLC1B may be mapping between D2S1381 and D2S176, within a region of 6.66-Mb. Five of the 23 prioritized genes maps within this refined region, of which 2 (UNC50, FHL2) were screened and excluded as the GLC1B candidates. Screening of these 7 new genes revealed a total of 22 DNA alterations, of which 7 were exonic. The 3 non-synonymous variations observed in TGOLN2 (R359W, F553L) and FHL2 (R88K) considered as non-disease causing. Although no mutations were found within the coding regions of these genes, other mutations within their non-coding or regulatory regions cannot be ruled out.
Conclusions::
The GLC1B locus may be limited to a region of 6.66-Mb that is flanked by D2S1381 and D2S176. Screening of 7 new candidate genes did not reveal any disease-causing mutations. Screening of other prioritized genes from this region is currently in progress.
Keywords: gene screening • genetics • linkage analysis