TABLE I.
Studies With Significant Associations of AD+P to Serotonin and Dopamine Receptors, COMT, DAOA, APP, SORL1, BACE1, and MAPT
| Gene | Number of studies reported | # of AD subjects included across all studies | Outcomes |
|---|---|---|---|
| HTR2A | 8 | 1,645 | 5-HT2A C102 allele associated with risk of psychosis [Holmes et al., 1998; Nacmias et al., 2001; Rocchi et al., 2003; Assal et al., 2004] |
| Genotype significant for delusions and CC genotype protective for delusions [Lam et al., 2004] | |||
| Three studies did not find genotype or allele frequency significant for psychosis [Craig et al., 2007; Wilkosz et al., 2007; Pritchard et al., 2008a] | |||
| HTR2C | 3 | 701 | 5-HT2C Ser23 allele frequency significant for visual hallucinations [Holmes et al., 1998] |
| Two other studies found allele frequency to be not significant for psychosis [Assal et al., 2004; Pritchard et al., 2008a] | |||
| One study found genotype to be not significant for psychosis [Pritchard et al., 2008a] | |||
| SLC6A4 | 6 | 1,315 | L allele and LL genotype significant for psychosis [Sweet et al., 2001] |
| LL genotype significant for protecting against delusions [Borroni et al., 2006] | |||
| Ten-repeat allele significant for psychosis [Pritchard et al., 2007] | |||
| Two other studies did not find genotype significant for psychosis [Ha et al., 2005; Ueki et al., 2007] and one study did not find allele frequency significant for psychosis [Rocchi et al., 2003] | |||
| DRD1 | 2 | 356 | B2/B2 genotype significant for psychosis [Sweet et al., 1998] |
| B1/B2 genotype significant for hallucinations [Holmes et al., 2001] | |||
| DRD2 | 1 | 267 | Cys311 allele frequency not significant for psychosis [Sweet et al., 1998] |
| DRD3 | 3 | 789 | Ser/Ser and Gly/Gly genotype significant for psychosis [Sweet et al., 1998] |
| Gly/Gly genotype significant for protecting against delusions [Holmes et al., 2001] | |||
| One study found allele frequency and genotype not significant for psychosis [Craig et al., 2004] | |||
| DRD4 | 1 | 225 | Allele frequency not significant for psychosis [Sweet et al., 1998] |
| SLC6A3 | 1 | 395 | Genotype not significant for psychosis [Pritchard et al., 2008b] |
| COMT | 2a | 693a | rs4680 G allele frequency significant for psychosis [Sweet et al., 2005; Borroni et al., 2006, 2007] |
| DAOA | 1 | 185 | Nominally significant association (P <0.05) with one SNP (rs2153674) [DiMaria et al., 2009] |
| APP | 1 | 867 | No association of SNPs tagging the majority of genetic variation within each of the target genes with AD+P [DeMichele-Sweet et al., 2011b] |
| SORL1 | |||
| BACE1 | |||
| MAPT |
HTR2A, serotonin 2A receptor; HTR2C, serotonin 2C receptor; SLC6A4, serotonin transporter; DRD1, dopamine-1 receptor; DRD2, dopamine-2 receptor; DRD3, dopamine-3 receptor; DRD4, dopamine-4 receptor; SLC6A3, dopamine transporter; COMT, catechol-O-methyltransferase; DAOA, D-amino acid oxidase activator; MAPT, microtubule-associated protein tau; APP, amyloid beta (A4) precursor protein; BACE1, beta-site APP-cleaving enzyme 1; SORL1, sortilin-related receptor, L(DLR Class) A repeats containing.
Borroni et al. [2006] study had 232 subjects and the same study was continued with new results published in 2007 which included 88 new subjects with AD.