No association between body mass index and beta(3)-adrenergic receptor variant (W64R) in children with premature pubarche and adolescent girls with hyperandrogenism

ADRB3 polymorphism associated with BMI gain in Japanese men

Objective. The aim of this study was to evaluate the association between the Trp64Arg polymorphism in the beta3-adrenergic receptor gene (ADRB3: rs4994) and BMI and serological and anthropometric data in healthy Japanese. Methods. Healthy Japanese recruited in a large-scale integrated manufacturing facility in Japan (N = 1355; age: 37.25 ± 9.43; BMI: 22.86 ± 3.46) were eligible for analysis. The anthropometric data and serological data were measured during a comprehensive health check, and a self-reporting questionnaire was used to assess lifestyle habits (current exercise, smoking status, alcohol intake, and working style) and weight at age 20. Genotyping for the ADRB3 polymorphism was performed by PCR-RFLP method. Results. Among 1355 participants, the genotype frequencies of the Trp/Trp, Trp/Arg, and Arg/Arg variants were 920 (67.9%), 394 (29.1%), and 41 (3.05%), respectively. In the multivariate analysis, a multiple linear regression model in men for the adjustment of age, drinking habits, smoking habits, exercise habits, working status and serological measurements statistically showed an overall weak significance between annual BMI gain from age 20 and age, LDL or ADRB3 polymorphism. Conclusions. The level of LDL, age, and ADRB3 polymorphism (Arg/Arg genotype) were statistically associated with annual BMI gain in Japanese men.

Genetic variation of FTO and TCF7L2 in premature adrenarche

Premature adrenarche (PA) has been associated with increased body mass index. Our aim was to determine whether the obesity-associated variant at fat mass and obesity gene (FTO) is more frequent in PA subjects. Furthermore, we hypothesized that altered Wnt signaling due to genetic variants at transcription factor 7-like 2 (TCF7L2) could play a role in the polygenic pathogenesis of PA. We genotyped polymorphisms at FTO rs9939609 and at TCF7L2 rs7903146 and rs12255372 in 73 Finnish white prepubertal children with PA and in 97 age- and sex-matched healthy controls. In addition, we investigated the associations of these genetic variations with weight, height, circulating adrenocortical hormone levels, glucose metabolism, lipid profile, and blood pressure. The differences in the minor allele frequencies (MAFs) of rs9939609, rs7903146, and rs12255372 were not statistically significant between the PA and control groups (difference in MAFs [95% confidence interval]: -0.06 [-0.18, 0.05], 0.04 [-0.05, 0.12], and 0.01 [-0.07, 0.10]; P = .3, .4, and .8, respectively). However, the risk allele at TCF7L2 rs7903146 was more frequent in PA subjects than in controls when we restricted the analysis to the subjects with lower weight-for-height than the median of the PA subjects (weight-for-height <108%, corresponding body mass index SD score <0.79; difference in MAFs [95% confidence interval]: 0.12 [-0.001, 0.23]; P = .038). Risk variant at FTO rs9939609 associated with higher weight-for-height in the healthy children (P = .001). In conclusion, the minor variant at FTO rs9939609 seems to play no major role in the increased weight-for-height of PA subjects; but the risk allele at TCF7L2 rs7903146 may have a role in the pathogenesis of PA in lean subjects.

Variation analysis of beta3-adrenergic receptor and melanocortin-4 receptor genes in childhood obesity

BACKGROUND

Decreased energy expenditure and increased food intake are principal causes for obesity. In the present study, genotypes of beta(3)-adrenergic receptor (beta(3)AR) and of melanocortin-4 receptor (MC4R), both of which are believed to have a close link to the cause of obesity, were analyzed and compared with phenotypes of childhood obesity.

METHODS

Thirty-five obese children with moderate to severe obesity were enrolled. Direct sequencing of the MC4R coding region and pinpoint-polymerase chain reaction were used to detect genomic variation in the beta(3)AR gene using peripheral blood-derived DNA.

RESULTS

Allele frequency of Trp64Arg variation in the beta(3)AR gene in the obese subjects was 0.16, which is comparable with that in the healthy general population in eastern Asia. Comparison of phenotypical characteristics did not show a significant difference between Trp/Trp and Trp/Arg subjects. It was notable that body height SD was significantly higher in the Trp/Trp than the Trp/Arg subjects (0.93 +/- 1.0 SD vs 0.07 +/- 1.3 SD, P= 0.03). Annual weight gains were far beyond a hypothetical fat gain in an Arg64 heterozygote with decreased energy consumption, suggesting increased food intake in childhood obesity. There was, however, no variation in the MC4R gene despite thorough sequencing of the entire coding region.

CONCLUSIONS

The Trp64Arg variation in the beta(3)AR gene has no relationship to the degree or the incidence of childhood obesity. The majority of childhood obesity can be characterized as tall stature, more rapid weight gain than that expected by decreased energy expenditure. Further investigation is necessary in regard to the increased food intake as a major cause of childhood obesity.

Female precocious puberty, obesity and polycystic-like ovaries

OBJECTIVE

To evaluate the characteristics of obese girls with gonadotropin releasing hormone-dependent precocious puberty with and without polycystic-like ovaries.

METHODS

Forty-seven overweight (> 75(th) centile of the Italian reference data) girls with a diagnosis of isosexual precocious puberty underwent auxological analysis, hormonal assay and utero-ovarian sonographic and Doppler evaluation. On the basis of sonography the patients were subdivided into two groups, girls presenting normal ovaries (Group I; n = 31) and those with polycystic-like ovaries (Group II; n = 16).

RESULTS

The mean body weight was significantly higher (P = 0.003) in Group II than it was in Group I. In addition, the patients with polycystic-like ovaries fell within our definition of superobese (> or = 97(th) centile of the Italian reference data) in 44% of cases. The uterine and ovarian volumes were significantly greater in Group II compared with Group I patients. The Doppler evaluation showed intraparenchymal ovarian vascularization and low downstream impedance to flow in all patients in Group II.

CONCLUSIONS

Girls with precocious puberty and polycystic ovaries, compared with those without polycystic ovaries, have a higher incidence of body weight exceeding the 85(th) centile of the Italian reference data (obesity).

The molecular-genetic basis of functional hyperandrogenism and the polycystic ovary syndrome

The genetic mechanisms underlying functional hyperandrogenism and the polycystic ovary syndrome (PCOS) remain largely unknown. Given the large number of genetic variants found in association with these disorders, the emerging picture is that of a complex multigenic trait in which environmental influences play an important role in the expression of the hyperandrogenic phenotype. Among others, genomic variants in genes related to the regulation of androgen biosynthesis and function, insulin resistance, and the metabolic syndrome, and proinflammatory genotypes may be involved in the genetic predisposition to functional hyperandrogenism and PCOS. The elucidation of the molecular genetic basis of these disorders has been burdened by the heterogeneity in the diagnostic criteria used to define PCOS, the limited sample size of the studies conducted to date, and the lack of precision in the identification of ethnic and environmental factors that trigger the development of hyperandrogenic disorders. Progress in this area requires adequately sized multicenter collaborative studies after standardization of the diagnostic criteria used to classify hyperandrogenic patients, in whom modifying environmental factors such as ethnicity, diet, and lifestyle are identified with precision. In addition to classic molecular genetic techniques such as linkage analysis in the form of a whole-genome scan and large case-control studies, promising genomic and proteomic approaches will be paramount to our understanding of the pathogenesis of functional hyperandrogenism and PCOS, allowing a more precise prevention, diagnosis, and treatment of these prevalent disorders.

Tryptophan 64 --> arginine polymorphism of beta-3-adrenergic receptor in Chilean women with polycystic ovary syndrome

OBJECTIVE

To establish the frequency of the Trp64Arg polymorphism of the beta3 adrenergic receptor (ADRB3) in women with polycystic ovary syndrome (PCOS) from a Chilean population, focusing particularly on the interaction with body weight. In addition, we evaluated the relationship of the Trp64Arg variant with other metabolic components of this syndrome.

PATIENTS AND DESIGN

In a case-control design study, a total of 106 women with clinical and hormonal evidence of PCOS and 82 healthy women (HW) were evaluated.

MEASUREMENTS

An oral glucose tolerance test (OGTT) was performed and serum glucose and insulin were measured before the glucose load and 30, 60, 90 and 120 min after. Lipid profile was determined in the basal sample. Insulin resistance was assessed by the homeostatic model assessment (HOMA(IR)) and insulin sensitivity index (ISI) composite. A polymerase chain reaction restriction fragment length polymorphism (PCR-RFLP) analysis was performed to determine the Trp64Arg polymorphism of ADRB3.

RESULTS

The frequency of the heterozygous condition was similar between PCOS and HW (39%vs. 35%). Only two subjects were homozygous for arginine, both belonging to the PCOS group and having a body mass index (BMI) > 30 kg/m2. In the crude analysis, hypothesis tests and odds ratios show that there is no evidence of association between the ADRB3 Trp64Arg variant and PCOS (P = 0.47). Moreover, when data were stratified by BMI categories, the statistical test for interaction between Trp64 carrier status and obesity was not significant (P = 0.29). This variant was present in 52% of the obese PCOS patients and 40% of the obese HW. In normal weight and obese PCOS carriers, the presence of the Trp64Arg variant was associated with high triglyceride (TG) levels. A major effect of the Trp64Arg variant on insulin resistance parameters could not be demonstrated.

CONCLUSIONS

The frequency of the Trp64Arg polymorphism was similar in healthy women and PCOS women, and a possible interaction between the effect of this variant and obesity in PCOS could not be demonstrated. However, our results showed an association between triglyceride levels and the presence of this genetic variant in PCOS women.

Frequency of the T228A polymorphism in the SORBS1 gene in children with premature pubarche and in adolescent girls with hyperandrogenism

OBJECTIVE

Because the metabolic actions of insulin are more impaired than the mitogenic pathways in polycystic ovary syndrome (PCOS), genes coding for proteins involved in insulin-mediated glucose transport can be considered as candidate genes. The sorbin and SH3-domain-containing-1 (SORBS1) gene codes for c-Cbl-associated protein (CAP) involved in insulin-mediated glucose uptake. An association study showed that a missense variant of the SORBS1 gene is protective against obesity and diabetes. We tested the hypothesis that the frequency of the protective allele would be decreased in children with premature pubarche and adolescent girls with hyperandrogenism.

DESIGN

Association study.

SETTING

Academic research environment.

PATIENT(S)

Children referred for the evaluation of premature pubarche (n = 79), adolescent girls with hyperandrogenism (n = 56), and healthy nondiabetic controls (n = 50).

INTERVENTION(S)

None.

MAIN OUTCOME MEASURE(S)

Frequency of the T228A allele in our patients and the relationship of body mass index to presence or absence of the T228A variant in our patient population.

RESULT(S)

Using allele-specific restriction fragment length polymorphism, allele frequencies were found to be similar among the premature pubarche, hyperandrogenism, and control groups (6.0%, 4.6%, and 8.0%, respectively). No statistically significant relationships were found between the SORBS1 genotypes and body mass index or hormone status.

CONCLUSION(S)

This SORBS1 polymorphism does not play a major role in premature pubarche, hyperandrogenism, and/or polycystic ovary syndrome in our patient population.

Inter- and intrafamilial variability in premature pubarche and polycystic ovary syndrome

OBJECTIVE

To ascertain the extent of phenotypic heterogeneity for premature pubarche and polycystic ovary syndrome between and within families.

DESIGN

Association study.

SETTING

Academic research environment.

PATIENT(S)

Three families in which the propositus had presented with either premature pubic hair or adolescent hyperandrogenism.

INTERVENTION(S)

Detailed medical histories, hormone determinations, and genotype analyses.

MAIN OUTCOME MEASURE(S)

Clinical phenotype. Genotypes for CYP21, HSD3B2, G972R variant of IRS-1, N363S variant of GRL, W64R variant of ADRB3, CAG repeat in exon 1 of AR, MspAI polymorphism in CYP17, and R264C variant of CYP19.

RESULT(S)

Significant phenotypic and genetic heterogeneity was observed both within and between families. In one family, CYP21 and IRS-1 variants were observed to co-segregate with symptoms of androgen excess and obesity. No genetic markers were consistently noted to associate with clinical features of hyperandrogenism in the other two families.

CONCLUSION(S)

The difficulties in classifying female family members as clearly affected or unaffected and lack of definitive male phenotype complicate the use of linkage analysis to identify the polycystic ovary syndrome genes. Each family is best considered on an individual basis to identify genetic markers that segregate with the clinical features of androgen excess.

Inconsistent effects of the proline12 --> alanine variant of the peroxisome proliferator-activated receptor-gamma2 gene on body mass index in children and adolescent girls

OBJECTIVE

To ascertain whether variation in peroxisome proliferator-activated receptor-gamma (PPAR-gamma), a nuclear ligand-dependent transcription factor affecting both adipocyte differentiation and insulin sensitivity, influences body mass index (BMI).

DESIGN

Association study.

SETTING

Academic research environment.

PATIENT(S)

Children with premature pubic hair and adolescent girls with hyperandrogenism.

INTERVENTION(S)

Assay for P12A and P115Q variants and measure BMI.

MAIN OUTCOME MEASURE(S)

BMI and PPAR-gamma genotypes.

RESULT(S)

Fourteen subjects were heterozygous for P12A; two were homozygous. None carried the P115Q allele. No significant differences in BMI or basal androstenedione concentrations between P12 carriers and noncarriers were found. Thirty-nine subjects had BMI values at two time points; mean BMI was significantly greater in the P12A carriers at time point 2. Those P12A carriers obese at time point 1 became more obese; lean mutation carriers tended to remain lean. Annual rate of increase in BMI was significantly greater in the P12A carriers than the noncarriers.

CONCLUSION(S)

Our findings suggest that P12A may be a genetic marker indicating risk for obesity persisting into adolescence. Future studies are needed to determine whether the divergent effects of P12A persist into adulthood, to elucidate the mechanism of this effect, and to replicate our findings in other populations.

Obesity, polycystic ovary syndrome and anovulation--how are they interrelated?

Polycystic ovary syndrome remains a mystery with respect to its aetiology, consequences and management. There is an increasing emphasis on its familial origins although the genes involved are unknown. There are significant changes in risk profiles for cardiovascular disease but no clear clinical evidence of morbidity or mortality. There is evidence of improvement in insulin resistance or insulin sensitivity drugs but uncertainty about improvement in pregnancy outcomes. This review looks at the latest advances in understanding polycystic ovary syndrome, particularly in obesity.

Candidate gene analysis in premature pubarche and adolescent hyperandrogenism

OBJECTIVE

To identify genetic markers associated with premature pubarche in children and hyperandrogenism in adolescent girls.

DESIGN

Association study.

SETTING

Academic research environment.

PATIENT(S)

Forty children with premature pubarche (PP), 29 adolescent girls with hyperandrogenism (HA), and 15 healthy control women.

INTERVENTION(S)

None.

MAIN OUTCOME MEASURE(S)

Genetic variations at five loci selected because of known associations with hyperandrogenism, insulin resistance, hyperinsulinemia, or obesity.

RESULT(S)

Heterozygosity for CYP21 mutations was identified in 14 of 40 (35%) PP, 8 of 29 (28%) HA, and 1 of 30 (3%) controls. Heterozygosity for HSD3B2 variants was identified in 3 of 40 (7.5%) PP, 5 of 29 (17%) HA, and 0/15 controls. Among the PP, 11 of 80 (14%), 5 of 80 (6%), and 7 of 80 (9%) alleles showed the IRS-1, GRL, and ADRB3 variants, respectively. Among the HA, 5 of 58 (8.6%), 3 of 58 (5%), and 6 of 58 (10%) alleles showed the IRS-1, GRL, and ADRB3 variants, respectively. Among the control participants, variant allele frequency was 1 of 30 (3.3%) for IRS-1, 2 of 30 (6.6%) for GRL, and 2 of 30 (6.6%) for ADRB3.

CONCLUSION(S)

Our findings suggest that the development of PP and HA can be associated with the occurrence of multiple sequence variants at five susceptibility loci, especially steroidogenic enzyme genes. This approach offers a novel paradigm to investigate and identify the genetic factors relevant to polycystic ovary syndrome.