ABSTRACT
BACKGROUND/AIMS: Loss of heterozygosity (LOH) has been discovered in retinoblastoma (RB) in previous studies. In this study, we aimed to discover potential tumour suppressor genes through investigation of the incidence of allelic loss in chromosome 1, 6, 9, 13, 19, 20, 21, 22 and X in Chinese sporadic retinoblastoma patients and to study the expression of genes flanking LOH region 13q31. METHODS: Twenty-five microdissected RB samples were analysed to investigate the LOH in 140 microsatellite markers. Expression of genes flanking D13S265 was investigated by real-time quantitative-PCR on available frozen samples. The promoter and entire coding region of GPC6 were examined for sequence changes in an extended batch of 29 RB samples. RESULTS: Allele losses were found in 92% (23/25) of the tumours. We identified a new LOH locus at 13q31 (D13S265) with a high occurrence rate (67%, 14/21) apart from the RB1 locus (68%, 17/25). Expression study detected the reduced expression of Glypican 6 (GPC6) transcript significantly associated with the LOH at 13q31 (p=0.024). Furthermore, mutation screening revealed no remarkable sequence alteration in GPC6 that could affect its expression. CONCLUSION: Results suggest that a reduction in GPC6 mRNA in retinoblastoma is associated with the non-random allelic loss at 13q31 that could contribute to RB development.
Subject(s)
Chromosomes, Human, Pair 13/genetics , Glypicans/biosynthesis , Loss of Heterozygosity , Retinal Neoplasms/genetics , Retinoblastoma/genetics , Child, Preschool , Chromosome Mapping , DNA Mutational Analysis/methods , Gene Expression , Glypicans/genetics , Humans , Infant , Microdissection/methods , Microsatellite Repeats , Neoplasm Proteins/metabolism , Prognosis , RNA, Messenger/genetics , RNA, Neoplasm/genetics , Retinal Neoplasms/metabolism , Retinal Neoplasms/pathology , Retinoblastoma/metabolism , Retinoblastoma/pathology , Tumor Cells, CulturedABSTRACT
We report the first use in Hong Kong of molecular techniques to screen prenatally for retinoblastoma and review 17 cases of retinoblastoma seen at the Hong Kong Eye Hospital from 2001 to 2006. A pregnant couple whose first child had retinoblastoma requested prenatal screening for retinoblastoma during their second pregnancy in 2000. Whole RB1 coding gene sequencing was performed on peripheral blood cells taken from family members and cultured amniocytes collected from the foetus during the 14th week of gestation. No RB1 gene mutations were found in the amniocyte samples and at birth the baby had no evidence of ocular tumours. During 5 years of follow-up the child remained healthy with intact visual function. Prenatal diagnosis of retinoblastoma alleviates parental stress and improves the perinatal care of affected family members.
Subject(s)
Genetic Testing , Prenatal Diagnosis , Retinal Neoplasms/genetics , Retinoblastoma/genetics , Adult , Female , Hong Kong , Humans , Male , Pedigree , Polymerase Chain Reaction , Pregnancy , Retinal Neoplasms/diagnosis , Retinoblastoma/diagnosis , Retinoblastoma Protein/geneticsABSTRACT
PURPOSE: Variants in the complement factor H (CFH) gene have been shown to be strongly associated with age-related macular degeneration (AMD). In this study, sequence alterations in CFH were investigated in 163 Chinese patients with exudative AMD and 155 unrelated Chinese control subjects. METHODS: All the 22 CFH exons, intron-exon boundaries, and promoter sequences were screened by polymerase chain reaction and DNA sequencing. RESULTS: Fifty-eight sequence changes, 42 of them novel, were identified. Six SNPs with an allele frequency >30% were significantly associated with exudative AMD. SNP rs3753396 was novel; the rest had been reported: rs3753394, rs551397, rs800292, rs2274700, and rs1329428. Two haplotype blocks were constructed. The TG haplotype for rs551397 and rs800292 was the major haplotype that conferred a significantly increased susceptibility to exudative AMD (P(corr) = 0.0001, OR = 1.91, 95% CI = 1.36-2.68). CONCLUSIONS: The findings support prior evidence that the CFH gene is one of the AMD-associated genes. There is a different distribution pattern of CFH variants in the Chinese compared with other populations. Individual SNP and haplotype analyses revealed that the ancient alleles at the 5' end of CFH contribute to an increased susceptibility to exudative AMD.
