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1.  MHC associations with clinical and autoantibody manifestations in European SLE 
Genes and immunity  2014;15(4):210-217.
Systemic lupus erythematosus (SLE) is a clinically heterogeneous disease affecting multiple organ systems and characterized by autoantibody formation to nuclear components. Although genetic variation within the major histocompatibility complex (MHC) is associated with SLE, its role in the development of clinical manifestations and autoantibody production is not well defined. We conducted a meta-analysis of four independent European SLE case collections for associations between SLE sub-phenotypes and MHC single-nucleotide polymorphism genotypes, human leukocyte antigen (HLA) alleles and variant HLA amino acids. Of the 11 American College of Rheumatology criteria and 7 autoantibody sub-phenotypes examined, anti-Ro/SSA and anti-La/SSB antibody subsets exhibited the highest number and most statistically significant associations. HLA-DRB1*03:01 was significantly associated with both sub-phenotypes. We found evidence of associations independent of MHC class II variants in the anti-Ro subset alone. Conditional analyses showed that anti-Ro and anti-La subsets are independently associated with HLA-DRB1*0301, and that the HLA-DRB1*03:01 association with SLE is largely but not completely driven by the association of this allele with these sub-phenotypes. Our results provide strong evidence for a multilevel risk model for HLA-DRB1*03:01 in SLE, where the association with anti-Ro and anti-La antibody-positive SLE is much stronger than SLE without these autoantibodies.
PMCID: PMC4102853  PMID: 24598797
Sub-phenotype analysis; MHC; meta-analysis; genetics; systemic lupus erythematosus; Europeans
2.  Analysis of FTO gene variants with obesity and glucose homeostasis measures in the multiethnic Insulin Resistance Atherosclerosis Study cohort 
Previous studies have replicated the association of variants within FTO (fat mass- and obesity-associated) intron 1 with obesity and adiposity quantitative traits in populations of European ancestry. Non-European populations, however, have not been so intensively studied. The goal of this investigation was to examine the association of FTO single-nucleotide polymorphisms (SNPs), prominent in the literature in a multiethnic sample of non-Hispanic White American (n = 458), Hispanic American (n = 373) and African American (n = 288) subjects from the Insulin Resistance Atherosclerosis Study (IRAS). This cohort provides the unique ability to evaluate how variation within FTO influences measures of adiposity and glucose homeostasis in three different ethnicities, which were ascertained and examined using a common protocol.
A total of 26 FTO SNPs were genotyped, including those consistently associated in the literature (rs9939609, rs8050136, rs1121980, rs1421085, rs17817449 and rs3751812), and tested for association with adiposity and glucose homeostasis traits.
For the adiposity phenotypes, these and other SNPs were associated with body mass index (BMI) in both non-Hispanic Whites (P-values ranging from 0.015 to 0.048) and Hispanic Americans (P-values ranging from 7.1 × 10−6 to 0.027). In Hispanic Americans, four other SNPs (rs8047395, rs10852521, rs8057044 and rs8044769) still showed evidence of association after multiple comparisons adjustment (P-values ranging from 5.0 × 10−5 to 5.2 × 10−4). The historically associated BMI SNPs were not associated in the African Americans, but rs1108102 was associated with BMI (P-value of 5.4 × 10−4) after accounting for multiple comparisons. For glucose homeostasis traits, associations were seen with acute insulin response in non-Hispanic Whites and African Americans. However, all associations with glucose homeostasis measures were no longer significant after adjusting for multiple comparisons.
These results replicate the association of FTO intron 1 variants with BMI in non-Hispanic Whites and Hispanic Americans but show little evidence of association in African Americans, suggesting that the effect of FTO variants on adiposity phenotypes shows genetic heterogeneity dependent on ethnicity.
PMCID: PMC4068260  PMID: 21102551
FTO; association; adiposity traits; multiethnic sample; glucose homeostasis traits
5.  Implication of European-derived adiposity loci in African Americans 
Recent genome-wide association studies (GWAS) have identified multiple novel loci associated with adiposity in European-derived study populations. Limited study of these loci has been reported in African Americans. Here we examined the effects of these previously identified adiposity loci in African Americans.
A total of 46 representative single-nucleotide polymorphisms (SNPs) in 19 loci that were previously reported in GWAS in Europeans (including FTO and MC4R) were genotyped in 4992 subjects from six African-American cohorts. These SNPs were tested for association with body mass index (BMI) after adjustment for age, gender, disease status and population structure in each cohort. Meta-analysis was conducted to combine the results.
Meta-analysis of 4992 subjects revealed seven SNPs near four loci, including NEGR1, TMEM18, SH2B1/ATP2A1 and MC4R, showing significant association at 0.005
We replicated the association of variants at four loci in six African-American cohorts that demonstrated a consistent direction of association with previous studies of adiposity in Europeans. These loci are all highly expressed in the brain, consistent with an important role for central nervous system processes in weight regulation. However, further comprehensive examination of these regions may be necessary to fine map and elucidate for possible genetic differences between these two populations.
PMCID: PMC3306054  PMID: 21750520
body mass index; genome-wide association; African Americans

Results 1-5 (5)