Family based association analyses between the serotonin transporter gene polymorphism (5-HTTLPR) and neuroticism, anxiety and depression.

We studied the association between the short/long promotor-based length polymorphism of the serotonin transporter gene (5-HTTLPR) and neuroticism, anxiety and depression. Subjects included twins, their siblings and parents from the Netherlands Twin Register (559 parents and 1,245 offspring). Subjects had participated between one and five times in a survey study measuring neuroticism, anxiety and depression. Offspring of these families were also approached to participate in a psychiatric interview diagnosing DSM-IV major depression. Within-family and total association between 5-HTTLPR and these traits were tested. Only three of the 36 tests showed a significant effect of 5-HTTLPR (P<0.05). These effects were in opposite directions, i.e. both negative and positive regression coefficients were found for the s allele. No additive effect of the s allele was found for DSM-IV depression. Our results strongly suggest that there is no straightforward association between 5-HTTLPR and neuroticism, anxiety and depression.