Biomedical subjects

Afshan Siddiq

Publications and source records attributed to Afshan Siddiq.

4 recordsLinked to original sources

PubMed2005

ACDC/adiponectin and PPAR-gamma gene polymorphisms: implications for features of obesity.

OBJECTIVE: The main purpose of this study was to investigate associations of single-nucleotide polymorphisms (SNPs) in the adipocyte C1q and collagen domain-containing (ACDC) gene and its regulator, the nuclear peroxisome proliferator-activated receptor (PPAR)-gamma gene, with body fat mass and its topographical distribution in postmenopausal women. RESEARCH METHODS AND PROCEDURES: Participants were 1501 healthy women, 60 to 85 years old, who were genotyped for four SNPs in the ACDC gene (-11391G/A, -11377C/G, +45T/G, +276G/T) and the Pro12Ala SNP in the PPAR-gamma gene. Total body fat mass and the central to peripheral fat mass ratio (CFM/PFM ratio) were measured using DXA. Adiponectin and homeostasis model assessment of insulin resistance were measured in 287 subjects. RESULTS: The -11377C/G SNP was associated with adiponectin (p < 0.001) and the CFM/PFM ratio (p = 0.005); the G allele being associated with low adiponectin and high CFM/PFM ratio. Similar associations of adiponectin (p = 0.0001) and the CFM/PFM ratio (p = 0.002) characterized the 1_2 (G_G) promoter haplotype (11391G/A_-11377C/G). Genotype variation of SNP Pro12Ala was associated with total body fat mass (p = 0.04); women with GG being the most obese (p = 0.01). The Ala/Ala (GG) genotype of Pro12Ala SNP interacted with the CC genotype of SNP-11377C/G in the determination of BMI (p = 0.001), when analyzed using a codominant model. DISCUSSION: Polymorphisms in the ACDC gene are associated with body fat distribution, whereas the Pro12Ala polymorphism in PPAR-gamma is associated with overall adiposity, apparently in interaction with an ACDC promoter SNP.

Absorptiometry, Photon↗

PubMed2005

A synonymous coding polymorphism in the alpha2-Heremans-schmid glycoprotein gene is associated with type 2 diabetes in French Caucasians.

alpha2-Heremans-Schmid glycoprotein (AHSG) is an abundant plasma protein synthesized predominantly in the liver. The AHSG gene, consisting of seven exons and spanning 8.2 kb of genomic DNA, is located at chromosome 3q27, a susceptibility locus for type 2 diabetes and the metabolic syndrome. AHSG is a natural inhibitor of the insulin receptor tyrosine kinase, and AHSG-null mice exhibit significantly enhanced insulin sensitivity. These observations suggested that the AHSG gene is a strong positional and biological candidate for type 2 diabetes susceptibility. Direct sequencing of the AHSG promoter region and exons identified nine common single nucleotide polymorphisms (SNPs) with a minor allele frequency > or =5%. We carried out a detailed genetic association study of the contribution of these common AHSG SNPs to genetic susceptibility of type 2 diabetes in French Caucasians. The major allele of a synonymous coding SNP in exon 7 (rs1071592) presented significant evidence of association with type 2 diabetes (P = 0.008, odds ratio 1.27 [95% CI 1.06-1.52]). Two other SNPs (rs2248690 and rs4918) in strong linkage disequilibrium with rs1071592 showed evidence approaching significance. A haplotype carrying the minor allele of SNP rs1071592 was protective against type 2 diabetes (P = 0.014). However, our analyses indicated that rs1071592 is not associated with the evidence for linkage of type 2 diabetes to 3q27.

Adult↗

PubMed2004

Adiponectin gene polymorphisms and adiponectin levels are independently associated with the development of hyperglycemia during a 3-year period: the epidemiologic data on the insulin resistance syndrome prospective study.

The plasma concentration of the adipocyte-derived peptide adiponectin is decreased in patients with obesity and type 2 diabetes. The adiponectin gene is located on chromosome 3q27, where a diabetes susceptibility locus has been mapped. Adiponectin gene polymorphisms (single nucleotide polymorphisms [SNPs]) have been associated with BMI, insulin sensitivity, and type 2 diabetes in some cross-sectional studies. Our aim was to assess the contribution of these SNPs in the development of features of the insulin resistance syndrome in a 3-year prospective study in approximately 4,500 French Caucasian subjects from the Epidemiologic Data on the Insulin Resistance Syndrome (DESIR) cohort. For subjects who were normoglycemic at baseline, the 3-year risk of becoming hyperglycemic (diabetes or impaired fasting glucose) was affected by two SNPs: G-11391A and T45G. For G-11391A, the risk was increased in GA carriers (odds ratio [OR] adjusted for sex [versus GG] = 1.60 [95% CI 1.16-2.20]; P = 0.004). For T45G, it was increased in GG carriers (OR [versus TT] = 2.71 [1.31-5.60]; P = 0.007). After 3 years, GG subjects had a greater increase in BMI (P = 0.009) and waist-to-hip ratio (P = 0.007). Adiponectin levels at baseline were associated with the development of hyperglycemia (P = 0.005), but the predictive effects on the risk for hyperglycemia were independent of adiponectin genotypes. In conclusion, in the DESIR study, variations at the adiponectin locus affect body weight gain, body fat distribution, and onset of hyperglycemia, as well as adiponectin levels. Adiponectin gene SNPs may have several phenotypic effects that co-occur with the development of the metabolic syndrome.

Adiponectin↗

PubMed2004

Genome-wide linkage analysis for severe obesity in french caucasians finds significant susceptibility locus on chromosome 19q.

To ascertain whether distinct chromosomal loci existed that were linked to severe obesity, as well as to utilize the increased heritability of this excessive phenotype, we performed a genome-wide scan in severely obese French Caucasians. The 109 selected pedigrees, totaling 447 individuals, required both the proband and a sibling to be severely obese (BMI >or=35 kg/m(2)), and 84.8% of the nuclear families possessed >or=1 morbidly obese sibling (BMI >or=40). Severe and morbid obesity are still relatively rare in France, with rates of 2.5 and 0.6%, respectively. The initial genome scan consisted of 395 evenly spaced microsatellite markers. Six regions were found to have suggestive linkage on 4q, 6cen-q, 17q, and 19q for a BMI >or=35 phenotypic subset, and 5q and 10q for an inclusive BMI >or=27 group. The highest peak on chromosome 19q (logarithm of odds [LOD] = 3.59) was significant by genome scan simulation testing (P = 0.042). These regions then underwent second-stage mapping with an additional set of 42 markers. BMI >or=35 analysis defined regions on 17q23.3-25.1 and 19q13.33-13.43 with an maximum likelihood score LOD of 3.16 and 3.21, respectively. Subsequent pooled data analysis with an additional previous population of 66 BMI >or=35 sib-pairs led to a significant LOD score of 3.8 at the 19q locus (empirical P = 0.023). For more moderate obesity and overweight susceptibility loci, BMI >or=27 analysis confirmed suggestive linkage to chromosome regions 5q14.3-q21.3 (LOD = 2.68) and 10q24.32-26.2 (LOD = 2.47). Plausible positional candidate genes include NR1H2 and TULP2.

Body Mass Index↗