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.

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.