ABSTRACT
BACKGROUND: Lactase non-persistence (LNP) has been associated with the CC genotype of -13910C > T and GG genotype of -22018G > A polymorphisms present upstream of the lactase gene. Lactose intolerance (LI) is caused when gastrointestinal symptoms develop in individuals with low lactase activity. OBJECTIVE: To analyse association of LNP genotype and LI symptoms with milk intake and determine whether factors such as age, gender and genotype affect LI status. SUBJECTS AND METHODS: Genetic analysis and lactose tolerance test (LTT) were performed on 205 healthy Indian adults. The pattern of milk consumption was recorded using a dietary questionnaire. RESULTS: LI was strongly associated with -13910CC genotype (OR = 10.28, 95% CI = 2.32-45.55, p = 0.002). Females were found to be at a higher risk of developing LI (OR = 2.47, 95% CI = 1.33-4.59, p = 0.004). The association of the ≥50 years age group with LI was marginally significant (OR = 1.86, 95% CI = 0.995-3.47, p = 0.05). Frequency and quantity of milk intake were lower in subjects belonging to the LNP genotype and LI groups (p < 0.05). CONCLUSIONS: Subject study suggests that gender and genotype may be associated with development of LI. Association of age with LI was marginal. The data also indicate that LNP genotype and LI may play a role in influencing milk intake in individuals.
Subject(s)
Asian People/genetics , Lactose Intolerance/genetics , Milk , Adolescent , Adult , Age Factors , Aged , Alleles , Animals , Female , Genetic Variation , Humans , India/epidemiology , Lactose Intolerance/epidemiology , Male , Middle Aged , Polymorphism, Single Nucleotide , Sex Factors , Young AdultABSTRACT
BACKGROUND: Lactase nonpersistence (LNP) is characterized by the decrease in lactase expression in the small intestine. Studies have shown that -13910 C>T and -22018 G>A single-nucleotide polymorphisms (SNPs) located upstream of the lactase gene are associated with an LNP/lactase persistence (LP) trait. OBJECTIVE: The current study evaluated the LP allelic frequency in 227 healthy Indian subjects consisting of North Indians, Maharashtrians, Gujaratis, Parsis, and South Indians, and for the first time assessed its relation with milk consumption pattern in Indian subjects. METHODS: The two SNPs were genotyped using the polymerase chain reaction and restriction fragment length polymorphism methods. The milk consumption pattern for the studied subjects was noted by questionnaire. RESULTS: The two SNPs were present in a strong linkage disequilibrium. LP prevalence varied in these Indian regional groups. The LP frequency was highest for North Indians and lowest for Parsis (p=0.03 CC vs. CT+TT, p=0.008 GG vs. GA+AA). South Indians had a lower LP frequency compared to North Indians (p=0.07 for each SNP). The milk consumption pattern varied in these Indian subgroups, with the Gujaratis exhibiting the highest milk intake and Parsis the lowest (p=0.04). CONCLUSION: Our study indicates that the milk intake in Indians might be influenced by their dietary habits in addition to their ancestral history. An overall correlation, however, between milk consumption and LP genotypes was not observed.
