Exploratory factor analysis of obsessive-compulsive patients and association with 5-HTTLPR polymorphism

Area of Science:

• Neuroscience
• Genetics
• Psychiatry

Background:

• The genetic underpinnings of obsessive-compulsive disorder (OCD) remain elusive, partly due to its complex and variable presentation.
• Previous hypotheses suggested serotonin dysfunction, but specific gene associations are not well-established.
• Phenotypic heterogeneity in OCD may hinder the identification of causative genes.

Purpose of the Study:

• To explore the association between quantitative OCD phenotypes and the serotonin transporter gene (5-HTTLPR) polymorphism.
• To investigate if specific symptom clusters in OCD correlate with genetic variations.
• To examine these associations within subgroups, particularly those with comorbid tic disorders.

Main Methods:

• Principal component analysis was used to derive five distinct symptom factors from the Yale-Brown Obsessive-Compulsive Scale (YBOCS).
• These factors were treated as quantitative phenotypes.
• Association analysis was performed between these phenotypes and the 5-HTTLPR insertion/deletion polymorphism.

Main Results:

• A trend towards an association was observed between the fifth factor (counting, repeating rituals) and 5-HTTLPR.
• In patients with a tic codiagnosis, a significantly higher score for the fifth factor was found in those with the L/L genotype compared to L/S and S/S genotypes.

Conclusions:

• The study suggests a potential genetic contribution to specific OCD symptom dimensions, particularly ritualistic behaviors.
• The serotonin transporter gene polymorphism (5-HTTLPR) may influence the expression of certain OCD symptoms, especially in individuals with comorbid tic disorders.
• Further research is warranted to elucidate the complex gene-environment interactions in OCD etiology.