The European lactase persistence genotype determines the lactase persistence state and correlates with gastrointestinal symptoms in the Hispanic and Amerindian Chilean population: a case–control and population-based study

Abstract

BackgroundThe lactase persistent (LP) or lactase non-persistent (LNP) state in European adults is genetically determined by a single nucleotide polymorphism (SNP) located 13.9 kb upstream of the lactase (LCT) gene, known as LCT C>T−13910 (rs4988235). The LNP condition leads to an inability to digest the milk sugar lactose leading to gastrointestinal symptoms and can affect nutrient and calcium intake in certain populations.ObjectivesThe authors studied a group of 51 Chilean patients to assess whether this SNP influences the LP/LNP state in this population, and determined the prevalence of LCT C>T−13910 genotypes in a representative sample of 216 Hispanics and 43 Amerindians with correlation to digestive symptoms.DesignCase–control study done in Chilean patients with clinical suspicion of LNP that were assessed using clinical survey, hydrogen breath test (HBT) and SNP genotyping. The population sample of Hispanics and Amerindians was assessed by clinical survey and SNP genotyping.ResultsOf the 51 patients with clinical suspicion of LNP, 29 were HBT-positive. The CC genotype (LNP) was present in 89.7% of the patients with positive HBT and in only 4.7% of those with negative HBT. The prevalence of the CC genotype was 56.9% in the Hispanic population and 88.3% in Amerindians, and was associated with a higher self-reported clinical intolerance to ingestion of dairy products.ConclusionThe LP/LNP state is determined by the LCT C>T−13910 variant in Chileans. This variant predicts digestive symptoms associated with the ingestion of lactose and is a good tool for the diagnosis of primary adult hypolactasia. The LCT T−13910 allele is rare in the Amerindian population and is suggestive of European ancestry in this contemporary population.

Prevalence of Lactose Intolerance in Chile: A Double-Blind Placebo Study

“…The study was conducted using healthy student volunteers. To determine the appropriate sample size based on previous studies [8], we assumed that 60% of the subjects would be LNP and 40% would be LP. Within these groups we assumed that 35% of LNP subjects and 10% of LP subjects would present with clinical lactose intolerance.…”

“…The LCT C>T -13910 variant was genotyped using the TaqMan allelic discrimination technique with real-time polymerase chain reaction (RT-PCR) [8,14] and was confirmed in 16 samples through direct sequencing (Macrogen, Seoul, Republic of Korea).…”

“…In the Chilean mestizo population there is a high prevalence (57%) of the LCT -13910 CC genotype, which is responsible for LNP [8]. However, the prevalence of lactose intolerance in this population remains unknown.…”

“…LP is a dominant autosomal condition associated with the presence of a single nucleotide polymorphism (SNP) and the most common SNP is LCT C>T -13910 (rs4988235) [6,7]. We recently reported that the European variant C>T -13910 also determines LP among the mestizo (43%) and Amerindian (12%) Chilean populations [8]. …”

Diagnóstico de intolerancia a la lactosa en adultos: rendimiento comparativo de la clínica, test de hidrógeno espirado y test genético

“…Poblaciones nativas de América presentan las mayores tasas reportadas 9 . En Chile, un estudio reciente demostró NPL (C/C _13910) en 56% de población hispana (mestiza) y en 88% de mapuches 14 . La mayoría de los sujetos NPL son asintomáticos o toleran dosis diarias de lactosa equivalentes a una taza de leche (12 g) y la mayoría de los que reportan intolerancia a lácteos no tienen realmente MAL 9 .…”