The corticotropin-releasing hormone gene and behavioral inhibition in children at risk for panic disorder.

Background: Behavioral inhibition to the unfamiliar (BI) is a heritable temperamental phenotype involving the tendency to display fearful, avoidant, or shy behavior in novel situations. BI is a familial and developmental risk factor for panic and phobic anxiety disorders. We previously observed an association between BI and a microsatellite marker linked to the corticotropin releasing hormone (CRH) gene in children at risk for panic disorder. To evaluate this further, we genotyped additional families for this marker and a panel of markers encompassing the CRH locus.

Methods: Sixty-two families that included parents with panic disorder and children who underwent laboratory-based behavioral observations were studied. Family-based association tests and haplotype analysis were used to evaluate the association between BI and polymorphisms spanning the CRH locus.

Results: We examined a set of markers which we found to reside in a block of strong linkage disequilibrium encompassing the CRH locus. The BI phenotype was associated with the microsatellite marker (p=.0016) and three single nucleotide polymorphisms (SNPs), including a SNP in the coding sequence of the gene (p=.023). Haplotype-specific tests revealed association with a haplotype comprising all of the markers (p=.015).

Conclusions: These results suggest that the CRH gene influences inhibited temperament, a risk factor for panic and phobic anxiety disorders. Genetic studies of anxiety-related temperament represent an important strategy for identifying the genetic basis of anxiety disorders.