Association of complement receptor 2 polymorphisms with innate resistance to HIV-1 infection.

HIV-1 induces activation of complement through the classical and lectin pathways. However, the virus incorporates several membrane-bound or soluble regulators of complement activation (RCA) that inactivate complement. HIV-1 can also use the complement receptors (CRs) for complement-mediated antibody-dependent enhancement of infection (C-ADE). We hypothesize that hypofunctional polymorphisms in RCA or CRs may protect from HIV-1 infection. For this purpose, 139 SNPs located in 19 RCA and CRs genes were genotyped in a population of 201 Spanish HIV-1-exposed seronegative individuals (HESN) and 250 HIV-1-infected patients. Two SNPs were associated with infection susceptibility, rs1567190 in CR2 (odds ratio (OR) = 2.27, P = 1 × 10(-4)) and rs2842704 in C4BPA (OR = 2.11, P = 2 × 10(-4)). To replicate this finding, we analyzed a cohort of Italian, sexually HESN individuals. Although not significant (P = 0.25, OR = 1.57), similar genotypic proportions were obtained for the CR2 marker rs1567190. The results of the two association analyses were combined through a random effect meta-analysis, with a significant P-value of 2.6 x 10(-5) (OR = 2.07). Furthermore, we found that the protective CR2 genotype is correlated with lower levels CR2 mRNA as well as differences in the ratio of the long and short CR2 isoforms.

SIRPB1 copy-number polymorphism as candidate quantitative trait locus for impulsive-disinhibited personality.

Impulsive-disinhibited personality (IDP) is a behavioral trait mainly characterized by seeking immediate gratification at the expense of more enduring or long-term gains. This trait has a major role in the development of several disinhibitory behaviors and syndromes, including psychopathy, attention-deficit and hyperactivity disorder, cluster-B personality disorders, criminality and alcoholism. Available data consistently support a strong heritable component, accounting for 30-60% of the observed variance in personality traits. A genome-wide analysis of copy-number variants was designed to identify novel genetic pathways associated with the IDP trait, using a series of 261 male participants with maximized opposite IDP scores. Quantitative trait locus analysis of candidate copy-number variants (CNVs) was conducted across the entire IDP continuum. Functional effects of associated variants were evaluated in zebrafish embryos. A common CNV mapping to the immune-related gene SIRPB1 was significantly associated with IDP scores in a dose-dependent manner (ß=-0.172, P<0.017). Expression quantitative trait locus analysis of the critical region revealed higher SIRPB1 mRNA levels associated with the haplotype containing the deleted allele (P<0.0007). Epigenetic marks highlighted the presence of two potential insulators within the deleted region, confirmed by functional assays in zebrafish embryos, which suggests that SIRPB1 expression rates are affected by the presence/absence of the insulator regions. Upregulation of SIRPB1 has been described in prefrontal cortex of patients with schizophrenia, providing a link between SIRPB1 and diseases involving disinhibition and failure to control impulsivity. We propose SIRPB1 as a novel candidate gene to account for phenotypic differences observed in the IDP trait.