Adult-type hypolactasia and lactose malabsorption in Poland.

BACKGROUND The available data on the incidence of lactose malabsorption are contradictory. Potential bias in random selection is a major drawback of studies performed to-date. Moreover, molecular analysis of polymorphism -13910 C>T upstream of the lactase (LCT) gene (NM_005915.4:c.1917+326C>T; rs4988235) has not been reported in those studies. Therefore, in this study we aimed to assess genetic predisposition and clinical manifestation of adult-type hypolactasia (ATH). PATIENTS AND METHODS In two-hundred randomly chosen healthy subjects (HS) aged from 18 to 20 years, the presence of -13910 C>T polymorphic variants upstream of the LCT gene was assessed. In a subgroup of subjects with genotype predisposing to ATH, hydrogen-methane breath test (BT) with lactose loading was conducted to determine the current state of lactase activity. In addition, clinical symptoms typical for lactose malabsorption were assessed using the questionnaire method. RESULTS Sixty-three out of 200 (31.5 %) HS had -13910 C/C genotype. Thus, genetically determined lactase persistence is expected in the remaining 137 (68.5 %) subjects. Thirteen out of 53 (24.5 %) HS having -13910 C/C genotype were proved to be lactose intolerant. Recalculating the data for the entire studied population it implies the incidence of lactose malabsorption in 7.7 % of subjects. Only three out of 13 (23.1 %) subjects with abnormal BT results, reported clinical symptoms related to lactose consumption. CONCLUSIONS Significantly lower than previously reported incidence of clinically detectable lactose malabsorption in young healthy adults in Poland has been documented. The -13910 C/C genotype upstream of the LCT gene indicates a predisposition to ATH, but definitely does not define the current ability to tolerate lactose.