Association of adiponectin promoter variants with traits and clusters of metabolic syndrome in Arabs: family-based study.

Plasma levels of adiponectin are decreased in type 2 diabetes, obesity and hypertension. Our aim was to use a family-based analysis to identify the genetic variants of the adiponectin (ADIPOQ) gene that are associated with obesity, insulin resistance, dyslipidemia and hypertension, among Arabs. We screened 328 Arabs in one large extended family for single nucleotide polymorphisms (SNPs) in the promoter region of the ADIPOQ gene. Two common SNPs were detected: rs17300539 and rs266729. Evidences of association between traits related to the metabolic syndrome and the SNPs were studied by implementing quantitative genetic association analysis. Results showed that SNP rs266729 was significantly associated with body weight (p-value=0.001), waist circumference (p-value=0.037), BMI (p-value=0.015) and percentage of total body fat (p-value=0.003). Up to 4.1% of heritability of obesity traits was explained by the rs266729 locus. Further cross-sectional analysis showed that carriers of the G allele had significantly higher values of waist circumference, BMI and percentage of total body fat (p-values 0.014, 0.004 and 0.032, respectively). No association was detected between SNP rs266729 and other clusters of metabolic syndrome or their traits except for HOMA-IR and fasting plasma insulin levels, p-values 0.035 and 0.004, respectively. In contrast, both measured genotype and cross-sectional analysis failed to detect an association between the SNP rs17300539 with traits and clusters of metabolic syndrome. In conclusion, we showed family-based evidence of association of SNP rs266729 at ADIPOQ gene with traits defining obesity in Arab population. This is important for future prediction and prevention of obesity in population where obesity is in an increasing trend.

A novel locus for hereditary spastic paraplegia with thin corpus callosum and epilepsy.

BACKGROUND: Hereditary spastic paraplegia (HSP) are classified clinically as pure when progressive spasticity occurs in isolation or complicated when other neurologic abnormalities are present. At least 22 genetic loci have been linked to HSP, 8 of which are autosomal recessive (ARHSP). HSP complicated with the presence of thin corpus callosum (HSP-TCC) is a common subtype of HSP. One genetic locus has been identified on chromosome 15q13-q15 (SPG11) for HSP-TCC, but some HSP-TCC families have not been linked to this locus. METHODS: The authors characterized two families clinically and radiologically and performed a genome-wide scan and linkage analysis. RESULTS: The two families had complicated ARHSP. The affected individuals in Family A had thin corpus callosum and mental retardation, whereas in Family B two of three affected individuals had epilepsy. In both families linkage analysis identified a locus on chromosome 8 between markers D8S1820 and D8S532 with the highest combined lod score of 7.077 at marker D8S505. This 9 cM interval located on 8p12-p11.21 represents a new locus for ARHSP-TCC. Neuregulin and KIF13B genes, located within this interval, are interesting functional candidate genes for this HSP form. CONCLUSION: Two consanguineous families with complicated autosomal recessive hereditary spastic paraplegia were clinically characterized and genetically mapped to a new locus on 8p12-p11.21.

A family study in Oman: large, consanguineous, polygamous Omani Arab pedigrees.

OBJECTIVE: To establish a suitable human model for the study of the genetics of complex diseases. METHODS: We have selected an Omani Arab population to provide the statistical power required to study the genetics of complex diseases with confidence. This model consists of five multigenerational highly inbred pedigrees, descending from a small number of founders just a few generations ago with environmental homogeneity, restricted geographical distribution, detailed records and well-ascertained and -validated pedigrees. Stringent criteria were adopted for defining the phenotypes of hypertension, diabetes mellitus, dyslipidemias and obesity. The SOLAR genetic software package was used to draw the pedigree structure. RESULTS: Outstanding statistical power to detect susceptibility loci was obtained. CONCLUSIONS: This model represents a large homogeneous human family-based population for the study of genetic and environmental factors contributing to complex diseases.

Support for linkage of familial combined hyperlipidemia to chromosome 1q21-q23 in Chinese and German families.

We examined familial combined hyperlipidemia (FCHL) families from nonisolated regions in Germany and China to see if we could corroborate support for a chromosome 1q FCHL locus in more general populations. We recruited 24 German families with 137 members, 92 of whom met the criteria of affected in terms of the low density lipoprotein (LDL) and triglyceride levels in excess of the 90th percentile for age and gender. In China, we recruited 12 families with a total of 81 members. All affected persons had total cholesterol concentrations >240 mg/dl and triglyceride concentrations >250 mg/dl. We examined the markers APOA2, D1S1677, D1S104, D1S194, D1S426, and D1S196. Two-point linkage analysis allowing for heterogeneity gave a maximum linkage of disorder score (HLOD) of 2.60 right over D1S194, estimating the proportion of linked families at 36%. This marker is adjacent to D1S104. The evidence for linkage was roughly the same both in the German (HLOD 1.40) and Chinese families (HLOD 1.52). Marker D1S194 is close to the retinoid X receptor (RXR) gene locus, which was found to be linked to triglyceride levels in an earlier twin study from our laboratory. We interpret our observations as encouraging support for the recent findings indicating the presence of a gene for FCHL on chromosome 1q. Furthermore, since DIS194 is adjacent to the gene for the RXR, we suggest that RXR is an attractive candidate for involvement in FCHL.

Cell targeting of a pore-forming toxin, CytA delta-endotoxin from Bacillus thuringiensis subspecies israelensis, by conjugating CytA with anti-Thy 1 monoclonal antibodies and insulin.

The cytolytic protein toxin CytA was linked to two monoclonal antibodies (mAb) directed against the mouse or the rat Thy 1 antigen. The purified CytA-mAb conjugates were not toxic to either target or nontarget cells. The conjugates did bind specifically to target cells since they agglutinated the target cells but not nontarget cells. When the conjugates were treated with dithiothreitol, the released CytA was toxic to all cells tested. These results suggested that the attachment of CytA to a molecule such as the mAb prevented it from forming a pore. Another conjugate was made by linking CytA to insulin. The purified insulin-CytA conjugate bound to and intoxicated cells bearing a high number of insulin receptors. Furthermore, the conjugate was far less toxic to cells expressing a low number of insulin receptors and not toxic to a known CytA target cell line from Aedes aegypti. However, CytA released from the conjugate by reduction was toxic to all cells tested. These results suggested that the cytotoxicity exhibited by CytA in the conjugate form against cells bearing insulin receptors was mediated through insulin and that, in the conjugate form, CytA no longer shows its broad in vitro cytolytic activity. The difference in toxicity between CytA-mAb conjugates and insulin-CytA conjugate is discussed in relation to size of the ligands, the number, distribution, and mobility of the target molecules, and intracellular trafficking.