High serum triglyceride (TG) levels is an established risk factor for coronary heart disease (CHD). Fat is stored in the form of TGs in human adipose tissue. We hypothesized that gene co-expression networks in human adipose tissue may be correlated with serum TG levels and help reveal novel genes involved in TG regulation.
Gene co-expression networks were constructed from two Finnish and one Mexican study sample using the blockwiseModules R function in Weighted Gene Co-expression Network Analysis (WGCNA). Overlap between TG-associated networks from each of the three study samples were calculated using a Fisher's Exact test. Gene ontology was used to determine known pathways enriched in each TG-associated network.
We measured gene expression in adipose samples from two Finnish and one Mexican study sample. In each study sample, we observed a gene co-expression network that was significantly associated with serum TG levels. The TG modules observed in Finns and Mexicans significantly overlapped and shared 34 genes. Seven of the 34 genes (ARHGAP30, CCR1, CXCL16, FERMT3, HCST, RNASET2, SELPG) were identified as the key hub genes of all three TG modules. Furthermore, two of the 34 genes (ARHGAP9, LST1) reside in previous TG GWAS regions, suggesting them as the regional candidates underlying the GWAS signals.
This study presents a novel adipose gene co-expression network with 34 genes significantly correlated with serum TG across populations.
Cites: Ann Clin Res. 1973 Jun;5(3):109-414584134
Cites: Genome Biol. 2011;12(3):R2221410973
Cites: Nat Genet. 2006 Feb;38(2):218-2216429159
Cites: PLoS Genet. 2006 Aug 18;2(8):e13016934000
Cites: Am J Hum Genet. 2007 Jun;80(6):1024-3617503322
Cites: Am J Physiol Gastrointest Liver Physiol. 2007 Jul;293(1):G1-417218471
Cites: Diabetologia. 2008 Jan;51(1):62-917972059
Cites: Bioinformatics. 2008 Mar 1;24(5):719-2018024473
Cites: Genome Res. 2008 May;18(5):706-1618347327
Cites: Am J Hum Genet. 2008 Aug;83(2):180-9218674750
We examined how genotype-environment correlation processes differ as a function of adolescent age. We tested whether adolescent age moderates genetic and environmental influences on positivity and negativity in mother-adolescent and father-adolescent relationships using parallel samples of twin parents from the Twin and Offspring Study in Sweden and twin/sibling adolescents from the Nonshared Environment in Adolescent Development Study. We inferred differences in the role of passive and nonpassive genotype-environment correlation based on biometric moderation findings. The findings indicated that nonpassive gene-environment correlation played a stronger role for positivity in mother- and father-adolescent relationships in families with older adolescents than in families with younger adolescents, and that passive gene-environment correlation played a stronger role for positivity in the mother-adolescent relationship in families with younger adolescents than in families with older adolescents. Implications of these findings for the timing and targeting of interventions on family relationships are discussed.
Adolescent alcohol abuse is associated with adverse outcomes in early adulthood, but differences in familial status and structure and household and community environments correlate with both adolescent drinking and adverse adult outcomes and may explain their association. We studied drinking-discordant twin pairs to evaluate such confounds to ask: Will between-family associations replicate in within-family comparisons?
With longitudinal data from >3,000 Finnish twins, we associated drinking problems at age 18½ with 13 outcomes assessed at age 25; included were sustained substance abuse, poor health, physical symptoms, early coital debut, multiple sexual partners, life dissatisfaction, truncated education, and financial problems. We assessed associations among twins as individuals with linear regression adjusted for correlated observations; within-family analyses of discordant twin pairs followed, comparing paired means for adult outcomes among co-twins discordant for adolescent problem drinking. Defining discordance by extreme scores on self-reported problem drinking at age 18½ permitted parallel analyses of twins as individuals and discordant twin pairs. Alternate definitions of pair-wise discordance and difference score correlations across the entire twin sample yielded supplementary analyses.
All individual associations were highly significant for all definitions of discordance we employed. Depending on definitions of discordance, 11 to 13 comparisons of all drinking-discordant twin pairs and 3 to 6 comparisons of discordant monozygotic (MZ) twin pairs replicated between-family associations. For most outcomes, effect size attenuated from individual-level analysis to that within discordant MZ twin pairs providing evidence of partial confounding in associations reported in earlier research. The exception was the General Health Questionnaire (GHQ); at age 25, GHQ-12 had equivalent associations with age 18½ Rutgers Alcohol Problem Index across all comparisons.
Our analyses control for shared family background, and, partly or fully, for shared genes, to yield within-family replications and more compelling evidence than previously available that adolescent alcohol abuse disrupts transitions into early adulthood.
The aims of the present study were to evaluate the contribution of the genetic and environmental factors to the risk of teenage childbearing, and to study whether life style, socio-economic conditions, and personality traits could explain possible familial effects. We linked two population-based registers: the Swedish Twin Register and the Swedish Medical Birth Register. The study covers female twin pairs born between 1953 and 1958, having their first infant before the age of 30 years (n = 1885). In order to separate familial effects from other environmental influences, and genetic effects from shared environmental effects, only complete twin pairs with known zygosity were included, in all 260 monozygotic and 370 dizygotic twin pairs. We used quantitative genetic analyses to evaluate the importance of genetic and environmental effects for liability to teenage childbearing. Logistic regression analyses were used to estimate the effects of life style, socio-economic situation, and personality on the probability of teenage childbearing, and to study whether psychosocial factors could explain possible familial effects. Fifty-nine percent (0-76%) of the variance in being a teenage mother was attributable to heritable factors; 0% (0-49%) was due to shared environmental factors; and 41% (23-67%) was explained by non-shared environmental factors. Thus, the data were consistent with the hypothesis that the familial aggregation of teenage childbearing is completely explained by genetic factors, although the alternative hypothesis that familial aggregation is entirely explained by shared environmental factors cannot be ruled out. Significant effects of smoking habits, housing conditions, and educational level were found in relation to liability to teenage childbearing. However, the familial effects on risk of teenage childbearing were not mediated through similarities in life style and socio-economic factors. When studying risk factors for teenage childbearing, it is recommended to include life style and socio-economic variables as well as information about family history of teenage childbearing. Twin Research (2000) 3, 23-27.
The ages of onset in multiple sclerosis cases span more than 7 decades. Data are presented for affected relative pairs from a Canadian population base of 30,000 multiple sclerosis index cases (1993-2008). The effects of genetic sharing, parent of origin, intergenerational versus collinear differences, and gender on the ages of onset were evaluated in the following concordant pairs: monozygotic twins (n = 29), dizygotic twins (n = 10), siblings (n = 614), first cousins (n = 405), half siblings (n = 29), parent/child (n = 285), and aunt/uncle/niece/nephew (avunculars) (n = 289). Fisher's z test assessed intraclass correlation (r) for ages of onset. Correlations for monozygotic twins, dizygotic twins, full siblings, and first cousins were 0.60, 0.54, 0.20, and 0.10, respectively. Dizygotic twins resembled monozygotic twins more than siblings. The age-of-onset correlation for maternal half siblings (r = 0.37) was higher than that for paternal half siblings (r = 0.26), consistent with other observations suggesting an intrauterine environmental effect on multiple sclerosis risk. Intergenerational comparisons are complicated by substantial increases of multiple sclerosis incidence over time. Genetic loading (familial vs. sporadic cases) did not generally influence the age of onset, but correlation of age of onset in multiple sclerosis relative pairs was proportional to genetic sharing. A maternal parent-of-origin effect on the age of onset in collinear generations was suggested.
Excess alcohol consumption and alcohol use disorders (AUDs) are associated with substantially increased mortality. Efforts to reduce this toll require an understanding of their causes.
To clarify the degree to which the excess mortality associated with AUDs arises (1) from the predispositions of the person who develops AUD (and which would likely be shared by close relatives) and (2) as a direct result of AUD itself.
A prospective cohort and co-relative design study involving all individuals born in Sweden from 1940 to 1965 who had neither died nor migrated prior to 1973 or age 15 years (N?=?2?821?036). They were followed up from January 1, 1973, until December 31, 2010. Alcohol use disorder was assessed from medical, criminal, and pharmacy registries. Half-siblings, full-siblings, and monozygotic twin pairs discordant for AUD were obtained from the Multi-Generation and Twin Register.
Death obtained from the Swedish Death registry.
Our cohort (1?447?887 males and 1?373?149 females) included 131?895 males and 42?163 females registered with AUD. The mean (SD) age at first AUD registration was 39 (13.4) years. We ascertained 127?347 and 76?325 deaths in the male and female subsamples, respectively. Controlling for sex, educational status, and year of birth, the mortality hazard ratio associated with AUD was 5.83 (95% CI, 5.76-5.90) and varied-with an inverted U-shaped function-by age. Examining the AUD-mortality association in the general population and in relative pairs discordant for AUD exposure demonstrated substantial familial confounding in early to mid-adulthood: the AUD-associated mortality hazard ratio was much lower in discordant close relatives than in the general population. In middle to late adulthood, evidence for familial confounding decreased with increasing evidence for a direct effect of AUD on elevated mortality. In the oldest age group (65-70 years), the mortality hazard ratios were similar across the population and all relative pairs, suggesting that the excess mortality was largely a result of having AUD. Adding years since onset of AUD to the model showed that both increasing age and increasing years of duration of AUD contributed to the reduction of familial confounding in the association between AUD and elevated mortality.
Excess mortality associated with AUD arises both from the predispositions of the person who develops AUD and the direct result of having AUD. The effect of predisposition is more prominent early in the life course and in the early years of AUD. The direct effect of AUD becomes progressively more important later in life and with longer duration of AUD. These results have implications for interventions seeking to reduce the elevated AUD-associated mortality.
Extended MHC haplotypes comprising HLA-A, -B, -DR, C2, BF and GLO1 loci observed in the parents of 497 Danish normal families are presented, with particular regard to the haplotypes that include BF variants or the C2*2 allele. The known association of HLA-B35, -DR1 with both -A3 and -A11 appeared to depend upon the BF type: HLA-B35, BF*S, -DR1 is strongly associated with -A11, whereas -B35,BF*F,-DR1 is strongly associated with -A3. Further, in the present material DZ twins of the same sex shared HLA-haplotypes more often than did twin pairs of different sex.
The authors tested the hypothesis that either prenatal feminization or masculinization hormone influences in utero or later socialization affects the risk for anorexia and bulimia nervosa and disordered eating in members of opposite-sex twin pairs.
Finnish twins (N=2,426 women, N=1,962 men with known zygosity) from birth cohorts born 1974-1979 were assessed at age 22 to 28 years with a questionnaire for eating disorder symptoms. Based on the questionnaire screen, women (N=292), men (N=53), and their cotwins were interviewed to assess diagnoses of anorexia nervosa and bulimia nervosa (per DSM-IV and broad criteria).
In women from opposite-sex twin pairs, the prevalence of DSM-IV or broad anorexia nervosa was not significantly different than that of women from monozygotic pairs or same-sex dizygotic pairs. Of the five male anorexia nervosa probands, only one was from an opposite-sex twin pair. Bulimia nervosa in men was too rare to be assessed by zygosity; the prevalence of DSM-IV or broad bulimia nervosa did not differ in women from opposite- versus same-sex twin pairs. In both sexes, the overall profile of indicators on eating disorders was rather similar between individuals from opposite- and same-sex pairs.
The authors found little evidence that the risk for anorexia nervosa, bulimia nervosa, or disordered eating was associated with zygosity or sex composition of twin pairs, thus making it unlikely that in utero femininization or masculinization or socialization effects of growing up with an opposite-sex twin have a major influence on the later development of eating disorders.