Several genetic studies of neuroticism not involving the advance specification of candidate genes also have been conducted. Genome-wide linkage studies, which use large numbers of markers selected from across the genome to examine patterns of inheritance within families, have not yielded consistent findings (Fullerton et al., 2003; Nash et al., 2004), perhaps partly because of limitations in the statistical power of linkage studies (Risch & Merikangas, 1996). A more powerful recent genome-wide association study of unrelated individuals failed to find significant associations between single nucleotide polymorphisms (SNPs) and neuroticism (Shifman et al., 2008), but another recent study found associations of neuroticism and SNPs in MAMDC1 (van den Oord et al., 2008).
