Lactase persistence/non‐persistence genetic variants in irritable bowel syndrome in an endemic area for lactose malabsorption

• DOI: 10.1111/j.1440-1746.2012.07259.x
• Publication Date: 2012-09-18T13:01:30Z
• Authors: Sunil Kumar; Prabhat Ranjan; Balraj Mittal; Rajan Singh; Uday C Ghoshal
• Keywords: Adult; Male; 0303 health sciences; Polymorphism, Genetic; Genotype; India; Middle Aged; Irritable Bowel Syndrome; 03 medical and health sciences; Lactose Intolerance; Gene Frequency; Sample Size; Intestine, Small; Humans; Female; Lactase

AbstractBackground and AimLactase non‐persistence is common in India. We evaluated: (i) frequency of lactase gene (C/T‐13910 and G/A‐22018) polymorphisms in irritable bowel syndrome (IBS) and healthy controls (HC), (ii) association between these polymorphisms and IBS‐subtypes and symptoms.MethodsA total of 150 IBS patients (Rome‐III criteria) and 252 age and gender‐matched HC were evaluated for C/T‐13910 and G/A‐22018 genotypes using polymerase chain reaction‐restriction fragment length polymorphism (PCR‐RFLP).ResultsTotals of 79 (52%), 52 (35%) and 19 (13%) patients had diarrhea‐predominant IBS (D‐IBS), constipation predominant IBS (C‐IBS) and alternating diarrhea and constipation IBS (A‐IBS), respectively (Rome‐III). Frequency of C/T‐13910 [genotypes: CC 102 (68%), CT 43 (29%), TT 5 (3%) vs CC 155 (61%), CT 83 (33%), TT 14 (6%), P > 0.05] and G/A‐22018 [GG 97 (65%), GA 41 (27%), AA 12 (8%) vs GG 154 (61%), GA 78 (31%), AA 20 (8%), P > 0.05] were similar among IBS and HC. Patients with D‐IBS more often had C/T‐13910 and G/A‐22018 genotypes than C‐IBS (CC 71 [90%], CT 6 [8%], TT 2 [2%]) versus (24 [46%], 25 [48%], 3 [6%]), A‐IBS (7 [39%], 12 [63%], 0, [0%]) and HC (155 [61%], 83 [33%], 14 [6%]), P < 0.0001 and (GG 69 [87%], GA 6 [8%], AA 4 [5%]) vs (22 [42%], 24 [46%], 6 [12%]) vs (6 [32%], 11 [58%], 2 [10%]), P < 0.0001. IBS with CC and GG genotypes more often had abdominal pain (P = 0.005), distension (P = 0.031) and higher stool frequency (P = 0.003) and reported symptoms following dairy products than non‐CC (P < 0.0001).ConclusionThough C/T‐13910 and G/A‐22018 polymorphisms were comparable among IBS and HC, these were more common among D‐IBS and reported some symptoms like abdominal pain, bloating and exacerbation by dairy products.