Diagnosis of adult-type hypolactasia/lactase persistence: genotyping of single nucleotide polymorphism (SNP C/T-13910) is not consistent with breath test in Colombian Caribbean population

Abstract

CONTEXT: Genotyping of single nucleotide polymorphism (SNP C/T-13910) located upstream of the lactase gene is used to determine adult-type hypolactasia/lactase persistence in North-European Caucasian subjects. The applicability of this polymorphism has been studied by comparing it with the standard diagnostic methods in different populations. OBJECTIVE: To compare the lactose hydrogen breath test with the genetic test in a sample of the Colombian Caribbean population. METHODS: Lactose hydrogen breath test and genotyping of SNP C/T-13910 were applied to 128 healthy individuals (mean age 35 ± 1). A positive lactose hydrogen breath test was indicative of hypolactasia. Genotyping was done using polymerase chain reaction/restriction fragment length polymorphism. The kappa index was used to establish agreement between the two methods. RESULTS: Seventy-six subjects (59%) were lactose-maldigesters (hypolactasia) and 52 subjects (41%) were lactose-digesters (lactase persistence). The frequencies of the CC, CT and TT genotypes were 80%, 20% and 0%, respectively. Genotyping had 97% sensitivity and 46% specificity. The kappa index = 0.473 indicates moderate agreement between the genotyping of SNP C/T-13910 and the lactose hydrogen breath test. CONCLUSION: The moderate agreement indicates that the genotyping of the SNP C/T-13910 is not applicable to determine adult-type hypolactasia/lactase persistence in the population participating in this study.

Keywords

• Intolerância à lactose
• Lactase
• Polimorfismo de um único nucleotídeo
• Testes respiratórios
• Colômbia
• Região do Caribe