4557 Background: In patients with metastatic midgut carcinoid tumors increased serotonin secretion is related to the carcinoid syndrome and mortality. Free serotonin is taken up via the serotonin transporter (5-HTT) in the liver and the lung and metabolized to 5- hydroxyindolacetic acid (5-HIAA) by Monoamine Oxidase A (MAO-A). The 5-HTT gene has a functional polymorphism in the promoter region (5-HTTPLR), with a short (S, less active) and long (L) allele and a polymorphic region in the second intron with variable number tandem repeats (VNTR-2). The MAO-A gene contains a length polymorphism in its promoter region (MAOA-LPR). To determine the clinical effects of the serotonin metabolizing capacity of individual patients, the association between different genotypes and symptoms (flushes and diarrhea) and survival was studied. Methods: 107 patients with metastatic midgut carcinoid tumors were genotyped for 5-HTTPLR, VNTR-2 and MAO-A-LPR. Differences were tested using Chi-square test and survival according to genotypes was analyzed using Kaplan Meier survival curves and tested with a log rank test. The independent effect of genotypes on survival was studied with multivariate Cox regression analysis with adjustments for the urinary 5-HIAA level, age at presentation and the presence of liver metastases. Results: The various genotypic variants were not related to flushes or diarrhea. Patients with the SS variant of 5-HTTLPR had a shorter median survival (45 months, 95% Confidence Interval (CI) 0.50–90) compared to patients with the LS (113 months, 95% CI 53–172) and the LL variant (90 months, 95% CI 64–115) (P=0.02). After adjustment, survival in patients with the SS variant remained worse with an odds ratio of 0.43 (95% CI 0.23–0.83; P=0.009) and 0.63 (95% CI 0.33–1.11; P=0.1) compared to patients with the LS and the LL variant respectively. Survival was not influenced by the VNTR-2 or MAOA-LPR. Conclusions: The SS genotype of the 5-HTTLPR is independently associated with a worse survival in patients with metastatic midgut carcinoid tumors. No significant financial relationships to disclose.
Associations of serotonin transporter gene promoter polymorphisms and monoamine oxidase A gene polymorphisms with oppositional defiant disorder in a Chinese Han population