Genetic variation of the mineralocorticoid receptor gene (MR, NR3C2) is associated with a conceptual endophenotype of "CRF-hypoactivity".
Recently, the "conceptual endophenotype" approach has been proposed as a means to identify subgroups of patients affected by stress-related psychiatric disorders. Conceptual endophenotypes consist of patterns of psychological, biological, and symptomatic elements. We studied a sample of patients seeking help for psychosomatic and stress-related disorders (total N = 469), who were evaluated with a diagnostic instrument that integrates psychological and biological data to derive 13 endophenotypes, or Neuropattern. The goal of this study was to explore associations between common variations of the mineralocorticoid receptor gene (MR, NR3C2), and the 13 conceptual endophenotypes of Neuropattern, as well as with the respective biological and symptom measures. A common haplotype of the MR, comprised of two functional single nucleotide polymorphism (rs2070951 G/C & rs5522 A/G), was associated with the conceptual endophenotype CRF-hypoactivity, characterized by low cortisol levels at awakening and a symptom constellation often observed in atypical depression. Homozygous carriers of the G-A haplotype (haplotype 1), previously associated with reduced dispositional optimism, increased levels of rumination and higher risk for depression, more frequently endorsed this Neuropattern. In addition to the overall association between MR variation and CRF hypoactivity, we observed in the whole sample significant associations between MR haplotypes and cortisol awakening response patterns, as well as with symptoms that characterize the CRF hypoactivity endophenotype. If replicated, MR haplotype 1 might serve as a vulnerability marker for a disorder class characterized in biological terms by reduced cortisol levels, and in terms of symptom constellation by features often observed in atypical depression.