Learning Objective #1: Describe the link between SERT polymorphism and IBS

Learning Objective #2: Understand the relationship of genetic polymorphisms and psychological distress

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Background/Purpose: Nurses are involved in helping patients with IBS self manage their symptoms. Recent evidence suggest that functional polymorphisms of the serotonin reuptake transporter (SERT) may play an important role in mood modulation but less is known about its role in IBS. This study compared the relationship among SERT polymorphisms (s/s, s/l, l/l), psychological distress, GI symptoms, and predominant stool group in IBS. Methods: Subjects (n=51) with IBS (45 ± 16 years) were recruited for a cognitive-behavioral intervention. A 10ml blood sample was drawn and DNA isolated. Oligonucleotide primers flanking the 5-HTTLPR and corresponding to the nucleotide positions -1416 to -1397 and -910 to -888 of the 5-HTT gene 5' -flanking regulatory region were used to generate 484- and 528-bp fragments and PCR amplification performed. Psychological distress was measured with the Brief Symptoms Index-53; GI symptoms with the Functional GI Disorders-Rome II Integrative Questionnaire. Predominant stool group (diarrhea, constipation, alternating) was based on Rome II criteria. Results: Participants with the s/s polymorphism had twice the level of psychological distress compared to those with the s/l or l/l polymorphisms (s/s [n=11], M ± SD, 0.84 ± 0.54; s/l [n=22] 0.43 ± 0.35; l/l [n=18] 0.40 ± 0.32, p=.015). More participants with the s/s polymorphism reported “often –almost always” having pain discomfort/pain in their “belly or abdomen” during the prior year (s/s, 82%; s/l, 32%; l/l, 40%, p=.012) that lasted > 20 minutes although those with the l/l polymorphism also had longer pain relative to the s/l group (s/s, 55%; s/l, 23%; l/l, 67%, p=.012). Most rated their discomfort/pain as moderate-severe and reported that it interfered with their daily activities (s/s, 91%; s/l, 82%; l/l, 89%). Predominant stool did not differ by polymorphism. Conclusion: These results show differences in psychological distress and pain symptoms but not predominant stool group by SERT polymorphism.