New genetic loci link adipose and insulin biology to body fat distribution

Body fat distribution is a heritable trait and a well-established predictor of adverse metabolic outcomes, independent of overall adiposity. To increase our understanding of the genetic basis of body fat distribution and its molecular links to cardiometabolic traits, here we conduct genome-wide association meta-analyses of traits related to waist and hip circumferences in up to 224,459 individuals. We identify 49 loci (33 new) associated with waist-to-hip ratio adjusted for body mass index (BMI), and an additional 19 loci newly associated with related waist and hip circumference measures (P < 5 × 10−8). In total, 20 of the 49 waist-to-hip ratio adjusted for BMI loci show significant sexual dimorphism, 19 of which display a stronger effect in women. The identified loci were enriched for genes expressed in adipose tissue and for putative regulatory elements in adipocytes. Pathway analyses implicated adipogenesis, angiogenesis, transcriptional regulation and insulin resistance as processes affecting fat distribution, providing insight into potential pathophysiological mechanisms.

Genetic studies of body mass index yield new insights for obesity biology

Obesity is heritable and predisposes to many diseases. To understand the genetic basis of obesity better, here we conduct a genome-wide association study and Metabochip meta-analysis of body mass index (BMI), a measure commonly used to define obesity and assess adiposity, in up to 339,224 individuals. This analysis identifies 97 BMI-associated loci (P < 5 × 10−8), 56 of which are novel. Five loci demonstrate clear evidence of several independent association signals, and many loci have significant effects on other metabolic phenotypes. The 97 loci account for ~2.7% of BMI variation, and genome-wide estimates suggest that common variation accounts for >20% of BMI variation. Pathway analyses provide strong support for a role of the central nervous system in obesity susceptibility and implicate new genes and pathways, including those related to synaptic function, glutamate signalling, insulin secretion/action, energy metabolism, lipid biology and adipogenesis.

Celebrating difference/censoring difference? : Marie Chouinard’s bODY rEMIX

This paper examines performances that defy established representations of disease, deformity and bodily difference. Historically, the ‘deformed’ body has been cast – onstage and in sideshows – as flawed, an object of pity, or an example of the human capacity to overcome. Such representations define the boundaries of the ‘normal’ body by displaying its Other. They bracket the ‘abnormal’ body off as an example of deviance from the ‘norm’, thus, paradoxically, decreasing the social and symbolic visibility (and agency) of disabled people. Yet, in contemporary theory and culture, these representations are reappropriated – by disabled artists, certainly, but also as what Carrie Sandahl has called a ‘master trope’ for representing a range of bodily differences. In this paper, I investigate this phenomenon. I analyse French Canadian choreographer Marie Chouinard’s bODY rEMIX/gOLDBERG vARIATIONS, in which 10 able-bodied dancers are reborn as bizarre biotechnical mutants via the use of crutches, walkers, ballet shoes and barres as prosthetic pseudo-organs. These bodies defy boundaries, defy expectations, develop new modes of expression, and celebrate bodily difference. The self-inflicted pain dancers experience during training is cast as a ‘disablement’ that is ultimately ‘enabling’. I ask what effect encountering able bodies celebrating ‘dis’ or ‘diff’ ability has on audiences. Do we see the emergence of a once-repressed Other, no longer silenced, censored or negated? Or does using ‘disability’ to express the dancers’ difference and self-determination usurp a ‘trope’ by which disabled people themselves might speak back to the dominant culture, creating further censorship?

Regional chromosomal assignment of human renin gene to 1q12→qter and use in linkage studies in Charcot-Marie-Tooth disease

The gene for renin, previously mapped to human chromosome 1, was further localized to 1q12 → qter using human-mouse somatic cell hybrid DNAs. The renin DNA probe used (λ HR5) could detect a HindIII restriction fragment length polymorphism. When used in studies of 12 informative families, no linkage could be found between the renin and Charcot-Marie-Tooth disease. Furthermore, an association of any renin allele with hypertension was not apparent.

Chromosome I linkage studies in Charcot-Marie-Tooth neuropathy type I

Charcot-Marie-Tooth neuropathy type 1 (CMT1) is an autosomal dominant disorder of peripheral nerve. The gene for CMT1 was originally localized to chromosome 1 by linkage to the Duffy blood group, but it has since been shown that not all CMT1 pedigrees show this linkage. We report here the results of linkage studies using five chromosome 1 markers - Duffy (Fy), antithrombin III (AT3), renin (REN), β-nerve growth factor (NGFB), and salivary amylase (AMY1) - in 16 CMT1 pedigrees. The total lod scores exclude close linkage of CMT1 to any of these markers. However, individual families show probable linkage of CMT1 to Duffy, AT3, and/or AMY1. No linkage was indicated with REN or NGFB. These results indicate that possible location of a CMT1 gene between the AMY1 and AT3 loci at p21 and q23, respectively, on chromosome 1 and support the theory that there is at least one other CMT1 gene.

Heterogeneity evidence and linkage studies on Charcot-Marie-Tooth disease

Charcot-Marie-Tooth neuropathy type 1 (CMT1) is an autosomal dominant disorder originally localized to chromosome 1 by linkage to the Duffy blood group. Studies have since shown that the disorder may be heterogeneous, as not all families show this linkage. We tested genetic heterogeneity by the HOMOG computer program in 15 CMT1 pedigrees informative for Duffy. We detected no evidence for heterogeneity in this sample, but when we combined results with previously published lod scores, heterogeneity was statistically significant. Twelve of the 15 families studied did not show linkage to Duffy. We found six of these families to be informative for a chromosome 19 marker, apolipoprotein CII(ApoC2). Despite a previous report showing probable linkage of a non-Duffy-linked CMT1 pedigree to two chromosome 19 markers, we did not detect significant linkage of ApoC2 to CMT1 in these families.

Isolation and use of chromosome 1 probes for linkage studies on Charcot-Marie-Tooth disease

Nine probes were isolated from a human chromosome 1 enriched library and mapped to regions of chromosome 1 using somatic cell hybrid lines. One clone, LR67, which mapped 1q12→q23 detected a BglI RFLP. This probe, as well as 4 other known chromosome 1 markers, α-spectrin, Factor XIIIB, DR10 and DR78, were used for linkage studies in 15 Charcot-Marie-Tooth disease (CMT1) families. Close linking of CMT1 to any of the 5 markers was not indicated. Total lod scores excluded linkage of CMT1 to LR67 and to DR10 at 5 cM or less, to DR78 and 10 cM or less, α-spectrin at 15 cM or less and Factor XIIIB at 20 cM or less. Possible linkage, however, was shown between LR67 and CMT1 at a distance of 30 cM. Also linkage at a distance of 5 cM was detected between this probe and α-spectrin.

DNA probes in Charcot-Marie-Tooth neuropathy

Results of Duffy (Fy) linkage confirm genetic heterogeneity in Charcot-Marie-Tooth disease type 1 (CMT1). Of 11 families informative for Fy, four showed probable linkage with CMT1, seven showed probable non-linkage and two showed definite non-linkage. These results suggest that Fy linked CMT1 may be less common than previously thought. These results combined with those of another DNA probe for the antithrombin III gene confirm that there are at least two gene loci for CMT1, termed 1A and 1B.

Directional dominance on stature and cognition in diverse human populations

Homozygosity has long been associated with rare, often devastating, Mendelian disorders1, and Darwin was one of the first to recognize that inbreeding reduces evolutionary fitness2. However, the effect of the more distant parental relatedness that is common in modern human populations is less well understood. Genomic data now allow us to investigate the effects of homozygosity on traits of public health importance by observing contiguous homozygous segments (runs of homozygosity), which are inferred to be homozygous along their complete length. Given the low levels of genome-wide homozygosity prevalent in most human populations, information is required on very large numbers of people to provide sufficient power3, 4. Here we use runs of homozygosity to study 16 health-related quantitative traits in 354,224 individuals from 102 cohorts, and find statistically significant associations between summed runs of homozygosity and four complex traits: height, forced expiratory lung volume in one second, general cognitive ability and educational attainment (P < 1 × 10−300, 2.1 × 10−6, 2.5 × 10−10 and 1.8 × 10−10, respectively). In each case, increased homozygosity was associated with decreased trait value, equivalent to the offspring of first cousins being 1.2 cm shorter and having 10 months’ less education. Similar effect sizes were found across four continental groups and populations with different degrees of genome-wide homozygosity, providing evidence that homozygosity, rather than confounding, directly contributes to phenotypic variance. Contrary to earlier reports in substantially smaller samples5, 6, no evidence was seen of an influence of genome-wide homozygosity on blood pressure and low density lipoprotein cholesterol, or ten other cardio-metabolic traits. Since directional dominance is predicted for traits under directional evolutionary selection7, this study provides evidence that increased stature and cognitive function have been positively selected in human evolution, whereas many important risk factors for late-onset complex diseases may not have been.