Clinical evaluation, biochemistry and genetic polymorphism analysis for the diagnosis of lactose intolerance in a population from northeastern Brazil

Abstract

OBJECTIVE:This work aimed to evaluate and correlate symptoms, biochemical blood test results and single nucleotide polymorphisms for lactose intolerance diagnosis.METHOD:A cross-sectional study was conducted in Fortaleza, Ceará, Brazil, with a total of 119 patients, 54 of whom were lactose intolerant. Clinical evaluation and biochemical blood tests were conducted after lactose ingestion and blood samples were collected for genotyping evaluation. In particular, the single nucleotide polymorphisms C>T-13910 and G>A-22018 were analyzed by restriction fragment length polymorphism/polymerase chain reaction and validated by DNA sequencing.RESULTS:Lactose-intolerant patients presented with more symptoms of flatulence (81.4%), bloating (68.5%), borborygmus (59.3%) and diarrhea (46.3%) compared with non-lactose-intolerant patients (p<0.05). We observed a significant association between the presence of the alleles T-13910 and A-22018 and the lactose-tolerant phenotype (p<0.05). After evaluation of the biochemical blood test results for lactose, we found that the most effective cutoff for glucose levels obtained for lactose malabsorbers was <15 mg/dL, presenting an area under the receiver operating characteristic curve greater than 80.3%, with satisfactory values for sensitivity and specificity.CONCLUSIONS:These data corroborate the association of these single nucleotide polymorphisms (C>T-13910 and G>A-22018) with lactose tolerance in this population and suggest clinical management for patients with lactose intolerance that considers single nucleotide polymorphism detection and a change in the biochemical blood test cutoff from <25 mg/dL to <15 mg/dL.

Knowledge and Attitudes Towards Nutrigenetics: Findings from the 2019 Unified Forces Preventive Nutrition Conference (UFPN)

“…Genetic single nucleotide polymorphisms (SNPs) (C>T-13910 and G>A-22018), located upstream to the lactase gene, have been strongly associated with adult lactose intolerance / persistence in several populations [14][15][16]. Due to the complexity and sensitivity of common biochemical and histological current methods of diagnosis, incorporating genetic screening for these common variations can significantly improve early diagnosis of lactase intolerance, enabling nutritional strategies to alleviate gastrointestinal symptoms in parallel to providing RDA calcium intake [17]. Despite these advancements, translation of nutrigenetics to the clinical setting is challenging and gradual and should be incorporated in light of restricted and evidence-based knowledge [18].…”

Laktózintolerancia: a laktázgén C/T-13910 polimorfizmusának és a hidrogénkilégzési teszt pontosságának retrospektív kiértékelése gasztroenterológiai szakrendelésen

“…Pozitív laktózterhelés esetén (15-25 mg/dl vagy 170-225 mmol/l) a betegek 75,9%-ban a C>T 13910 polimorfizmusban CC, az A>G 22018-polimorfizmusban 66,7%-ban GG genotípusú, de az esetszám kicsi, és etnikailag kevert (fehér, illetve színes bőrű) volt [23].…”

Lactose tolerance test as an alternative to hydrogen breath test in the study of lactose malabsorption

“…Performance standardization has not yet been established, and a variety of protocols and cut-off values have been proposed to define lactose malabsorption. The most commonly used cut-off point for the increase in glucose concentrations with respect to baseline concentrations is 20 mg/dL [12], although 15 mg/dL has been reported to have better sensibility and specificity [7,13]. An important limitation is that this test is not valid or indicated for diabetic patients [14], and bacterial overgrowth can interfere with its interpretation.…”