Tryptophan hydroxylase 2 (TPH2) gene polymorphisms and psychiatric comorbidities in temporal lobe epilepsy

• We studied the influence of TPH2 gene variants on mental disorders in TLE.
• The presence of the A allele in the rs17110747 polymorphism increased the risk of alcohol abuse.
• Serotonergic system has a role in the expression of mental disorders in TLE.

Psychiatric comorbidities are frequent in temporal lobe epilepsy (TLE). It is plausible that variance in serotonin-related genes is involved in the susceptibility of these associations. We report here the results on the association of tryptophan hydroxylase 2 (TPH2) gene polymorphisms with psychiatric comorbidities in TLE. A cohort study was conducted on 163 patients with TLE. We assessed the influence of the rs4570625 and rs17110747 polymorphisms in the TPH2 gene on psychiatric comorbidities in TLE. In patients with TLE, the presence of the T allele in the rs4570625 polymorphism was associated with psychotic disorders (OR = 6.28; 95% CI = 1.27–17.54; p = 0.02), while the presence of the A allele in the rs17110747 polymorphism was associated with alcohol abuse (OR = 20.33; 95% CI = 1.60–258.46; p = 0.02). Moreover, we identified male gender (OR = 11.24; 95% CI = 1.68–76.92; p = 0.01) and family history of psychiatric disorder (OR = 15.87; 95% CI = 2.46–100; p = 0.004) as factors also associated with alcohol abuse in TLE. Conversely, a family history of epilepsy was inversely associated with alcohol abuse (OR = 0.03; 95% CI = 0.001–0.60; p = 0.02). Tryptophan hydroxylase 2 gene allele variants might be risk factors for psychiatric conditions in TLE. More specifically, we observed that the T allele in the rs4570625 polymorphism was associated with psychotic disorders, and the A allele in the rs17110747 TPH2 polymorphism was associated with alcohol abuse in patients with TLE. We believe that this study may open new research venues on the influence of the serotonergic system associated with psychiatric comorbidities in epilepsy.