Recently, an association of the Val66Met polymorphism of the brain-derived neurotrophic factor with hippocampal volume in patients with major depression has been reported. Here, we aimed at replicating this finding in an independent German sample. We included 79 patients with unipolar major depressive episodes and 84 healthy comparison participants. The brain-derived neurotrophic factor Val66Met polymorphism was determined in all participants. The volume of the hippocampus was manually traced on high-resolution magnetic resonance images. The hippocampal volumes of patients were significantly smaller than those of the comparison participants, confirming previous reports. There was, however, no Val66Met effect on hippocampal volume in either group. To conclude, we did not replicate the Val66Met effect on hippocampal volume in neither patients with major depression nor in healthy participants.

The human dopamine D2 receptor (DRD2) has been implied in the vulnerability for alcoholism and/or the modification of its severity. This is supported through animal experimental and pharmacological data. We analyzed the DRD2 311Ser/Cys polymorphism in 312 German alcoholics and 131 ethnically matched controls to investigate the association of genetic DRD2 variants with alcoholism or clinical characteristics of homogeneous subgroups of alcoholics. We observed no association between the 311Cys variant and alcoholism, and none of the clinical characteristics evaluated was significantly associated with 311Cys. The allele frequencies of the 311Cys variant were 0.026 and 0.031 in the alcoholics and controls, respectively. These are the highest reported 311Cys frequencies in Caucasians. The DRD2 TaqI A1/A2 restriction fragment length polymorphism was analyzed simultaneously in our samples. In most cases, the 311Cys allele is associated with the TaqI A2-allele. Data do not suggest a clinical relevance of the 311Cys variant in alcoholism. However, the relevance of this variant in other diseases or the existence of other DRD2 variants with altered receptor function or expression cannot be excluded.