Hopelessness, a potential endophenotpye for suicidal behavior, is influenced by TPH2 gene variants

► First report on association of hopelessness and TPH2 gene. ► A functional TPH2 SNP showed association with hopelessness and estimated suicidal risk. ► A risk and a protective haplotype of TPH2 gene for hopelessness are identified. ► Other depression symptoms than hopelessness failed to show association with TPH2 gene. ► Genetically determined hopelessness can be a new endophenotype for suicidal behavior.