Association between Obsessive Compulsive Disorder and Tumor Necrosis Factor-α Gene -308 (G>A) and -850 (C>T)...

Area of Science:

• Neurogenetics
• Immunology
• Pediatric Psychiatry

Background:

• Obsessive-compulsive disorder (OCD) is a neurobiological condition often linked to autoimmune mechanisms following Group A β-hemolytic streptococcus (GABHS) infections.
• Tumor necrosis factor-alpha (TNF-α), a key cytokine involved in apoptosis, plays a role in autoimmune diseases.

Purpose of the Study:

• To investigate the association between specific polymorphisms in the TNF-α gene promoter region (-308 G>A and -850 C>T) and their relationship with childhood-onset OCD.
• To explore potential correlations between these polymorphisms, OCD, and antistreptolysin O (ASO) titers.

Main Methods:

• Genotyping of TNF-α gene promoter polymorphisms (-308 and -850) using polymerase chain reaction (PCR), restriction fragment length polymorphism (RFLP), and polyacrylamide gel electrophoresis (PAGE).
• Diagnosis of childhood OCD in patients (n=49) and controls (n=58) aged 4-12 years using DSM-IV criteria and KSAD-S-PL.
• Measurement of antistreptolysin O (ASO) titers to assess streptococcal infection markers.

Main Results:

• A significant positive association was found between OCD and the TNF-α -308 (G>A) polymorphism (p < 0.001).
• No significant association was observed between OCD and the TNF-α -850 (C>T) polymorphism (p = 0.053).
• A significant association was identified between the TNF-α -850 polymorphism and ASO titers (p = 0.010), but not between the -308 polymorphism and ASO titers (p = 0.953).

Conclusions:

• The mutant AA genotype at the TNF-α -308 locus may serve as a molecular indicator for childhood-onset OCD.
• The mutant CT genotype at the TNF-α -850 locus shows a significant association with ASO titers, suggesting a potential link to streptococcal infections in OCD pathogenesis.