Objective: Many researches strongly suggest that early- and late-onset obsessive-compulsive disorder (OCD) represent separate subtypes of the disorder, possibly with distinct underlying pathogeneses. The aim of this study was to determine the association between 5-HTTLPR genotypes and the onset of OCD.
Methods: We recruited 124 OCD patients and classified them into an early-onset group (age of onset <18 years) and a late onset-group (age of onset ≥18 years). From the blood, DNA was isolated using standard techniques and the 5-HTTLPR polymorphism was genotyped by polymerase chain reaction and electrophoresis. We classified the subject as s/s, s/l, and l/l group according to their genotype. We also combined the s/l and l/l genotypes (l allele non-carrier) and compared these with the s/s genotype (l allele non-carrier) for our analysis. Genotype and allele frequencies of early- and late-onset OCD were analyzed by chi-square statistics.
Results: The frequencies of s/l+ l/l genotype and I allele in early-onset OCD group were significantly higher than late-onset OCD group.
Conclusion: These results suggest that a 5-HTTLPR polymorphism is an important factor in the onset of OCD.