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The reasons for the ethnic disparities in the prevalence of systemic lupus erythematosus (SLE) and the relative high frequency of SLE risk alleles in the population are not fully understood. Population genetic factors such as natural selection alter allele frequencies over generations and may help explain the persistence of such common risk variants in the population and the differential risk of SLE. In order to better understand the genetic basis of SLE that might be due to natural selection, a total of 74 genomic regions with compelling evidence for association with SLE were tested for evidence of recent positive selection in the HapMap and HGDP populations, using population differentiation, allele frequency, and haplotype-based tests. Consistent signs of positive selection across different studies and statistical methods were observed at several SLE-associated loci, including PTPN22, TNFSF4, TET3- DGUOK, TNIP1, UHRF1BP1, BLK, and ITGAM genes. This study is the first to evaluate and report that several SLE-associated regions show signs of positive natural selection. These results provide corroborating evidence in support of recent positive selection as onemechanism underlying the elevated population frequency of SLE risk loci and supports future research that integrates signals of natural selection to help identify functional SLE risk alleles. [ABSTRACT FROM AUTHOR]

Objective The proposed pathogenesis of the cardiac manifestations of neonatal lupus (cardiac-NL) involves maternal autoantibodies to the RNPs SSA/Ro and SSB/La, enhanced by as-yet-unknown factors that likely involve dysregulation of both inflammatory and fibrotic fetal responses. This study was designed to improve the power to detect specific associations in genes with candidate biologic functions. Methods Using data from our genome-wide association study of 116 Caucasian children with cardiac-NL and 3,351 Caucasian controls, we tested for enrichment of single-nucleotide polymorphism (SNP) associations in genes with candidate biologic functions related to fibrosis, immune function, apoptosis, T cell function, cell infiltration, innate immune cell function, interferon, Toll-like receptors, and calcium channels. After linkage disequilibrium pruning and exclusion of the extended HLA region, a total of 15,103 SNPs in 3,068 genes remained. Results A highly significant enrichment of P values was observed for genes related to fibrosis ( P = 2.27 × 10−9), apoptosis ( P = 7.67 × 10−7), and innate immune cell ( P = 2.53 × 10−6), immune ( P = 5.01 × 10−4), T cell ( P = 2.23 × 10−4), and interferon functions ( P = 1.64 × 10−3). The most significant non-HLA associations included the sialyltransferase gene ST8SIA2 (rs1487982; odds ratio 2.20 [95% confidence interval 1.52-3.19], P = 3.37 × 10−5), the integrin gene ITGA1 (rs2432143; odds ratio 2.31 [95% confidence interval 1.54-3.45], P = 4.54 × 10−5), and the complement regulator gene CSMD1 (rs7002001; odds ratio 2.41 [95% confidence interval 1.57-3.72], P = 6.33 × 10−5). Conclusion This study identified novel candidate genes associated with cardiac-NL and highlights the value of studying this cohort for advancing knowledge regarding the genetic etiology of this syndrome. Identification of causal alleles is expected to provide critical insight into the molecular mechanisms responsible for linking maternal autoantibodies to cardiac scarring in these fetuses/neonates. [ABSTRACT FROM AUTHOR]

OBJECTIVE--The Gullah-speaking African American population from the Sea Islands of South Carolina is characterized by a low degree of European admixture and high rates of type 2 diabetes and diabetic complications. Affected relative pairs with type 2 diabetes were recruited through the Sea Islands Genetic African American Registry (Project SUGAR). RESEARCH DESIGN AND METHODS--We conducted a genome-wide linkage scan, genotyping 5,974 single nucleotide polymorphisms in 471 affected subjects and 50 unaffected relatives from 197 pedigrees. Data were analyzed using a multipoint engine for rapid likelihood inference and ordered subsets analyses (OSAs) for age at type 2 diabetes diagnosis, waist circumference, waist-to-hip ratio, and BMI. We searched for heterogeneity and interactions using a conditional logistic regression likelihood approach. RESULTS--Linkage peaks on chromosome 14 at 123-124 cM were detected for type 2 diabetes (logarithm of odds [LOD] 2.10) and for the subset with later age at type 2 diabetes diagnosis (maximum LOD 4.05). Two linkage peaks on chromosome 7 were detected at 44-45 cM for type 2 diabetes (LOD 1.18) and at 78 cM for type 2 diabetes (LOD 1.64) and the subset with earlier age at type 2 diabetes diagnosis (maximum LOD 3.93). The chromosome 14 locus and a peak on 7p at 29.5 cM were identified as important in the multilocus model. Other regions that provided modest evidence for linkage included chromosome 1 at 167.5 cM (LOD 1.51) and chromosome 3 at 121.0 cM (LOD 1.61). CONCLUSIONS--This study revealed a novel type 2 diabetes locus in an African American population on 14q that appears to reduce age of disease onset and confirmed two loci on chromosome 7. Diabetes 58:260-267, 2009 [ABSTRACT FROM AUTHOR]