Prevalence of the TCF7L2 rs7903146 T allele in young Hispanic adults: Implications for colorectal cancer prevention.

Abstract

e22650 Background: Colorectal cancer (CRC) incidence has increased in recent years, particularly among young adults, raising concern about underlying genetic susceptibility factors. The rs7903146 single-nucleotide polymorphism (SNP) in the Transcription Factor 7-Like 2 ( TCF7L2 ) gene, widely studied for its role in type 2 diabetes risk, has also been associated with increased CRC susceptibility. Homozygosity for the T allele has been proposed to contribute to approximately 17% of CRC cases in certain populations. Methods: Undergraduate students from a South Florida college campus were recruited under an approved Institutional Review Board protocol. Participants provided informed consent and completed a demographic questionnaire. Saliva samples were collected for genomic DNA extraction using the InstaGene Matrix method. Genotyping of the TCF7L2 rs7903146 (C/T) variant was performed using real-time polymerase chain reaction. Genotype counts (CC, CT, TT) were obtained by direct count, and allele frequencies were calculated from these counts. The population was tested for Hardy–Weinberg equilibrium. Results: A total of 100 students were genotyped, all of whom self-identified as Hispanic or Latino. Genotype frequencies were consistent with the Hardy–Weinberg equilibrium. The frequency of the rs7903146 T allele was 0.310, and 8% of participants were homozygous for the TT genotype. Conclusions: Eight percent of the sampled population was homozygous for the TCF7L2 rs7903146 T risk allele. Because genetic screening can be performed at any age and before the development of clinically detectable physiological alterations, knowledge of genotype may support population-level risk stratification and inform preventive public health strategies. Although clinical outcomes were not assessed, these findings highlight the potential value of incorporating genetic information into future screening frameworks and longitudinal studies examining CRC risk in young adults.