Evidence for three genetic loci involved in both anorexia nervosa risk and variation of body mass index.

The maintenance of normal body weight is disrupted in patients with anorexia nervosa (AN) for prolonged periods of time. Prior to the onset of AN, premorbid body mass index (BMI) spans the entire range from underweight to obese. After recovery, patients have reduced rates of overweight and obesity. As such, loci involved in body weight regulation may also be relevant for AN and vice versa. Our primary analysis comprised a cross-trait analysis of the 1000 single-nucleotide polymorphisms (SNPs) with the lowest P-values in a genome-wide association meta-analysis (GWAMA) of AN (GCAN) for evidence of association in the largest published GWAMA for BMI (GIANT). Subsequently we performed sex-stratified analyses for these 1000 SNPs. Functional ex vivo studies on four genes ensued. Lastly, a look-up of GWAMA-derived BMI-related loci was performed in the AN GWAMA. We detected significant associations (P-values <5 × 10-5, Bonferroni-corrected P<0.05) for nine SNP alleles at three independent loci. Interestingly, all AN susceptibility alleles were consistently associated with increased BMI. None of the genes (chr. 10: CTBP2, chr. 19: CCNE1, chr. 2: CARF and NBEAL1; the latter is a region with high linkage disequilibrium) nearest to these SNPs has previously been associated with AN or obesity. Sex-stratified analyses revealed that the strongest BMI signal originated predominantly from females (chr. 10 rs1561589; Poverall: 2.47 × 10-06/Pfemales: 3.45 × 10-07/Pmales: 0.043). Functional ex vivo studies in mice revealed reduced hypothalamic expression of Ctbp2 and Nbeal1 after fasting. Hypothalamic expression of Ctbp2 was increased in diet-induced obese (DIO) mice as compared with age-matched lean controls. We observed no evidence for associations for the look-up of BMI-related loci in the AN GWAMA. A cross-trait analysis of AN and BMI loci revealed variants at three chromosomal loci with potential joint impact. The chromosome 10 locus is particularly promising given that the association with obesity was primarily driven by females. In addition, the detected altered hypothalamic expression patterns of Ctbp2 and Nbeal1 as a result of fasting and DIO implicate these genes in weight regulation.

A candidate syntenic genetic locus is associated with voluntary exercise levels in mice and humans.

Individual levels of physical activity, and especially of voluntary physical exercise, highly contribute to the susceptibility for developing metabolic, cardiovascular diseases, and potentially to psychiatric disorders. Here, we applied a cross-species approach to explore a candidate genetic region for voluntary exercise levels. First, a panel of mouse chromosome substitution strains was used to map a genomic region on mouse chromosome 2 that contributes to voluntary wheel running levels - a behavioral readout considered a model of voluntary exercise in humans. Subsequently, we tested the syntenic region (HSA20: 51,212,545-55,212,986) in a human sample (Saint Thomas Twin Register; n=3038) and found a significant association between voluntary exercise levels (categorized into excessive and non-excessive exercise) and an intergenic SNP rs459465 (adjusted P-value of 0.001). Taking under consideration the methodological challenges embedded in this translational approach in the research of complex phenotypes, we wanted to further test the validity of this finding. Therefore, we repeated the analysis in an independent human population (ALSPAC data set; n=2557). We found a significant association of excessive exercise with two SNPs in the same genomic region (rs6022999, adjusted P-value of P=0.011 and rs6092090, adjusted P-value of 0.012). We explored the locus for possible candidate genes by means of literature search and bioinformatics analysis of gene function and of trans-regulatory elements. We propose three potential human candidate genes for voluntary physical exercise levels (MC3R, CYP24A1, and GRM8). To conclude, the identified genetic variance in the human locus 20q13.2 may affect voluntary exercise levels.

Cross-species genetics converge to TLL2 for mouse avoidance behavior and human bipolar disorder.

Interspecies genetic analysis of neurobehavioral traits is critical for identifying neurobiological mechanisms underlying psychiatric disorders, and for developing models for translational research. Recently, after screening a chromosome substitution strain panel in an automated home cage environment, chromosomes 15 and 19 were identified in female mice for carrying genetic loci that contribute to increased avoidance behavior (sheltering preference). Furthermore, we showed that the quantitative trait locus (QTL) for baseline avoidance behavior on chromosome 15 is homologous with a human linkage region for bipolar disorder (8q24). Similarly, we now performed comparative analysis on the QTL for avoidance behavior found on chromosome 19 and correspondingly revealed an overlap of the mouse interval and human homologous region 10q23-24, which has been previously linked to bipolar disorders. By means of a comparative genetic strategy within the human homologous region, we describe an association for TLL2 with bipolar disorder using the genome-wide association study (GWAS) data set generated by the Wellcome Trust Case Control Consortium (WTCCC). On the basis of genetic homology and mood stabilizer sensitivity, our data indicate the intriguing possibility that mouse home cage avoidance behavior may translate to a common biochemical mechanisms underlying bipolar disorder susceptibility. These findings pave new roads for the identification of the molecular mechanisms and novel treatment possibilities for this psychiatric disorder, as well as for the validity of translational research of associated psychiatric endophenotypes.

Association study in eating disorders: TPH2 associates with anorexia nervosa and self-induced vomiting.

Twin studies suggest that genetic factors play a substantial role in anorexia nervosa (AN) and self-induced vomiting (SV), a key symptom that is shared among different types of eating disorders (EDs). We investigated the association of 25 single nucleotide polymorphisms (SNPs), capturing 71-91% of the common variance in candidate genes, stathmin (STMN1), serotonin receptor 1D (HTR1D), tryptophan hydroxylase 2 (TPH2) and brain-derived neurotrophic factor (BDNF), with AN and EDs characterized by regular SV. The first allele frequencies of all the SNPs were compared between a Dutch case group (182 AN, 149 EDs characterized by SV) and 607 controls. Associations rendering P-values < 0.05 from this initial study were then tested for replication in a meta-analysis with two additional independent ED case-control samples, together providing 887 AN cases, 306 cases with an ED characterized by SV and 1914 controls. A significant effect for the minor C-allele of tryptophan hydroxylase 2 rs1473473 was observed for both AN [odds ratio (OR) = 1.30, 95% CI 1.08-1.57, P < 0.003] and EDs characterized by SV (OR = 1.52, 95% CI 1.28-2.04, P < 0.006). In the combined case group, a dominant effect was observed for rs1473473 (OR = 1.38, 95% CI 1.16-1.64, P < 0.0003). The meta-analysis revealed that the tryptophan hydroxylase 2 polymorphism rs1473473 was associated with a higher risk for AN, EDs characterized by SV and for the combined group.

Early onset of breast carcinoma in African American women with poor prognostic factors.

The purpose of this study was to determine prognostic significance of age and race as independent variables and to see role of age at the onset of breast carcinoma. A retrospective study was conducted of African American and white women with breast cancer treated at SUNY-Health Science Center Brooklyn and Kings County Hospital Center from 1983 to 1993. The objective was to analyze the differences in patterns of disease onset, as related to age and prognostic factors. A total of 738 patients were analyzed for race-adjusted comparison of stage, grade, disease-free survival, and median survival. Age at the time of diagnosis was analyzed to conduct age-specific comparisons of African American (AA) and white patients. The multivariate analysis indicated that AA women develop breast cancer 10 years earlier than white women (p = 0.00001). Corrected by stage and grade, i.e., chi2 test for stage-by-stage and grade-by-grade analysis has revealed that the AA women present with higher stage (p = 0.009), increased number of positive nodes (p = 0.00007), and more estrogen receptor/ progesterone receptor-negative tumors (p = 0.005). Further studies are required to probe into the etiologic possibilities of this significant difference. The important contributing factors could be hormonal, genetic, environmental, and socioeconomic. Obesity and dietary factors also need to be evaluated. Further studies to explore genetic susceptibility by ploidy is recommended to explain this significant difference. We conclude that the onset of breast cancer among AA women occurs at a significantly younger age than in white women, and their prognostic factors are poorer.

Diminished survival of young blacks with adenocarcinoma of the prostate.

The survival rates of 117 black and white patients treated by primary radiation for carcinoma of the prostate at the State University of New York Health Science Center at Brooklyn and Kings County Hospital Center were analyzed according to age and race. In addition, stage, grade, and delay time in seeking medical attention were analyzed. Survival was similar in both young (less than 60 years) and old (greater than or equal to 60 years) patients, with 45% and 41% 5-year-survival rates, respectively. Survival was better in white patients, 48% 5-year survival, than in blacks, 35% 5-year survival. Black patients presented with higher stage disease than whites (p less than 0.01). This trend was even greater in young black males, who had higher grade (64% versus 11%; p less than 0.04) and higher stage tumors (p less than 0.05). In addition, young blacks delayed seeking medical attention greater than 3 months 72% of the time, as compared to 0% in white young males (p less than 0.005). A survival difference was also seen in young blacks as compared with young whites: 3.9-year median survival versus 6.0-year median survival, respectively.

Radiation-treated carcinoma of prostate. Comparison of survival of black and white patients by Gleason's grading system.

The survival of 117 black and white patients treated by radiation for carcinoma of the prostate at SUNY Health Science Center at Brooklyn (SUNY/HSCB) and Kings County Hospital Center (KCHC) was analyzed according to Gleason's grading system. The effect of total pattern score and its relationship to stage and survival and to race were intercompared. In both black and white racial groups, there was strong correlation between high pattern score and high stage p = less than 001. The percentage of black patients presenting with high pattern score (7-10) was significantly greater, 43 versus 27%; this adversely affected stage and survival. The median survival for white and black patients was 4.8 and 3.2 years, respectively; p = 0.007. Stage for stage and grade for grade, survival was similar in both racial groups.

Response of colo-rectal hepatic metastases to concomitant radiotherapy and intravenous infusion 5 fluorouracil.

Twenty-three patients with colo-rectal hepatic metastases were retrospectively reviewed after completing treatment with split course liver irradiation and continually infused concomitant intravenous 5-fluorouracil. Although no patient attained a complete response, an objective partial response was documented in 15 (Responders). The Responders had a median survival of 45 weeks whereas Non-responders had a median survival of 17 weeks. Patients with metastatic disease solely in the liver or those with a Karnofsky performance score (k.p.s) of over sixty, had a median survival of 49 weeks. Patients with multiple organ metastatic involvement had a median survival of 25 weeks and those with a Karnofsky with less than 60 had a median survival of 27 weeks. (p values of 0.006 and 0.03, respectively.) The overall survival of the group completing treatment was 30 weeks, and 19 patients (83%) achieved subjective palliation. The patients tolerated therapy well. There was minimal hematological toxicity; 3 patients developed a leucocyte count of less than 2000 and 1 developed a platelet count of 30,000. The palliation and prolongation of survival attained with minimal complications suggest that adjuvant liver irradiation with concomitant infusion 5-fluorouracil radiosensitization may be an option to offer patients identified to be at high risk of developing subclinical liver disease.