Distribution of the - 13910C>T polymorphism in the general population of Portugal and in subjects with gastrointestinal complaints associated with milk consumption.

Background: The - 13910C>T polymorphism has been associated with lactase persistence (LP) in European populations.

Aim: To assess - 13910C>T genotypes across Portugal and in adult individuals with unspecific gastrointestinal complaints associated with milk consumption.

Subjects And Methods: This study genotyped - 13910C>T in the general population from Northern (n = 64), Central (n = 70) and Southern (n = 65) Portugal and in 40 subjects with gastrointestinal symptoms. Additionally, the concordance was evaluated between breath-hydrogen test and - 13910C>T genotypes in 65 samples.

Results: An overall frequency of 0.349 for the LP - 13910*T allele was estimated in the general population, with a noticeable decrease in the South (0.269) compared with North (0.383) and Centre (0.393). Among the symptomatic group, the frequency of the - 13910*T allele (0.363) was not significantly different from the general population. A 94% concordance was found between the breath-hydrogen and the molecular tests.

Conclusions: This study suggests that (i) the distribution of the LP polymorphism is not uniform across the country, (ii) genotyping - 13910C>T is a good diagnostic tool for lactase status in the Portuguese population and (iii) self-reported gastrointestinal complaints are not good predictors of the LP status, implying that a significant part of those complaints may not be related to hypolactasia.