Type 2 diabetes, cardiovascular disease, and the evolutionary paradox of the polycystic ovary syndrome: a fertility first hypothesis

Association of Serum Selenium and Selenoprotein P with Oxidative Stress Biomarkers in Patients with Polycystic Ovary Syndrome

Polycystic ovary syndrome (PCOS) is the most common endocrine disorder in women of reproductive age which is characterized by various reproductive and metabolic disorders. Oxidative stress (OS) is now recognized to be involved in the pathogenesis of PCOS which could be targeted in the management of PCOS-related complications. Selenium (Se), as an antioxidant trace element, has been shown to decrease in PCOS patients. This study aimed to investigate the relationship between the Se and selenoprotein P (SELENOP) levels with OS markers in women with PCOS. In this cross-sectional study, 125 females aged 18-45 years diagnosed with PCOS were included. Demographic, clinical, and lifestyle information of participants were obtained using the relevant questionnaires. Fasting blood samples were collected to measure biochemical parameters. Serum levels of thiobarbituric acid reactive substances (TBARS), total antioxidant capacity (TAC), erythrocyte superoxide dismutase (SOD), glutathione peroxidase (GPx), and catalase activities as well as anthropometric measurements were assessed across tertiles of serum concentrations of Se and SELENOP. Higher serum levels of Se were associated with higher serum TAC levels (β=0.42, P<0.001) and erythrocytes GPx activity (β=0.28, P=0.002) as well as with lower serum TBARS levels (β= -0.26, P=0.003). Similarly, higher serum levels of SELENOP were associated with higher TAC (β=0.32, P<0.001) and erythrocyte GPx activity (β=0.30, P=0.001). SELENOP also showed an inverse association with serum levels of TBARS (β= -0.40, P<0.001). Nevertheless, erythrocytes SOD and CAT activities showed no significant relationships with serum Se and SELENOP concentrations (all P>0.05). The present study found that serum Se and SELENOP levels were inversely associated with TBARS levels and positively associated with TAC levels and erythrocytes GPx activity.

Evidence of positive selection of genetic variants associated with PCOS

STUDY QUESTION

Was polycystic ovary syndrome (PCOS), which impairs fertility and adheres to the evolutionary paradox, subject to evolutionary selection during ancestral times and did rapidly diminish in prevalence?

SUMMARY ANSWER

This study strengthened the hypothesis that positive selection of genetic variants occurred and may account for the high prevalence of PCOS observed today.

WHAT IS KNOWN ALREADY

PCOS is a complex endocrine disorder characterized by both reproductive and metabolic disturbances. As a heritable disease that impairs fertility, PCOS should diminish rapidly in prevalence; however, it is the most common cause of female subfertility globally. Few scientific genetic studies have attempted to provide evidence for the positive selection of gene variants underlying PCOS.

STUDY DESIGN, SIZE, DURATION

We performed an evolutionary analysis of 2,504 individuals from 14 populations of the 1000 Genomes Project.

PARTICIPANTS/MATERIALS, SETTING, METHODS

We tested the signature of positive selection for 37 single-nucleotide polymorphisms (SNPs) associated with PCOS in previous genome-wide association studies using six parameters of positive selection.

MAIN RESULTS AND THE ROLE OF CHANCE

Analyzing the evolutionary indices together, there was obvious positive selection at the PCOS-related SNPs loci, especially within the original evolution window of humans, demonstrated by significant Tajima's D values. Compared to the genome background, six of the 37 SNPs in or close to five genes (DENN domain-containing protein 1A: DENND1A, chromosome 9 open reading frame 3: AOPEP, aminopeptidase O: THADA, diacylglycerol kinase iota: DGKI, and netrin receptor UNC5C: UNC5C) showed significant evidence of positive selection, among which DENND1A, AOPEP, and THADA represent the set of most established susceptibility genes for PCOS.

LIMITATIONS, REASONS FOR CAUTION

First, only well-documented SNPs were selected from well-designed experiments. Second, it is difficult to determine which hypothesis of PCOS evolution is at play. After considering the most significant functions of these genes, we found that they had a wide variety of functions with no obvious association between them.

WIDER IMPLICATIONS OF THE FINDINGS

Our findings provide additional evidence for the positive evolution of PCOS. Our analyses require confirmation in a larger study with more evolutionary indicators and larger data range. Further research to identify the roles of the DENND1A, AOPEP, THADA, DGKI, and UNC5C genes is also necessary.

STUDY FUNDING/COMPETING INTEREST(S)

This study was supported by the National Key Research and Development Program of China (2021YFC2700400 and 2021YFC2700701), Basic Science Center Program of NSFC (31988101), CAMS Innovation Fund for Medical Sciences (2021-I2M-5-001), National Natural Science Foundation of China (82192874, 31871509, and 82071606), Shandong Provincial Key Research and Development Program (2020ZLYS02), Taishan Scholars Program of Shandong Province (ts20190988), and Fundamental Research Funds of Shandong University. The authors have no conflicts of interest to disclose.

TRIAL REGISTRATION NUMBER

N/A.

Polycystic Ovary Syndrome: An Evolutionary Adaptation to Lifestyle and the Environment

Polycystic ovary syndrome (PCOS) is increasingly recognized as a complex metabolic disorder that manifests in genetically susceptible women following a range of negative exposures to nutritional and environmental factors related to contemporary lifestyle. The hypothesis that PCOS phenotypes are derived from a mismatch between ancient genetic survival mechanisms and modern lifestyle practices is supported by a diversity of research findings. The proposed evolutionary model of the pathogenesis of PCOS incorporates evidence related to evolutionary theory, genetic studies, in utero developmental epigenetic programming, transgenerational inheritance, metabolic features including insulin resistance, obesity and the apparent paradox of lean phenotypes, reproductive effects and subfertility, the impact of the microbiome and dysbiosis, endocrine-disrupting chemical exposure, and the influence of lifestyle factors such as poor-quality diet and physical inactivity. Based on these premises, the diverse lines of research are synthesized into a composite evolutionary model of the pathogenesis of PCOS. It is hoped that this model will assist clinicians and patients to understand the importance of lifestyle interventions in the prevention and management of PCOS and provide a conceptual framework for future research. It is appreciated that this theory represents a synthesis of the current evidence and that it is expected to evolve and change over time.

The evolutionary biology of endometriosis

We provide the first analysis and synthesis of the evolutionary and mechanistic bases for risk of endometriosis in humans, structured around Niko Tinbergen's four questions about phenotypes: phylogenetic history, development, mechanism and adaptive significance. Endometriosis, which is characterized by the proliferation of endometrial tissue outside of the uterus, has its phylogenetic roots in the evolution of three causally linked traits: (1) highly invasive placentation, (2) spontaneous rather than implantation-driven endometrial decidualization and (3) frequent extensive estrogen-driven endometrial proliferation and inflammation, followed by heavy menstrual bleeding. Endometriosis is potentiated by these traits and appears to be driven, proximately, by relatively low levels of prenatal and postnatal testosterone. Testosterone affects the developing hypothalamic-pituitary-ovarian (HPO) axis, and at low levels, it can result in an altered trajectory of reproductive and physiological phenotypes that in extreme cases can mediate the symptoms of endometriosis. Polycystic ovary syndrome, by contrast, is known from previous work to be caused primarily by high prenatal and postnatal testosterone, and it demonstrates a set of phenotypes opposite to those found in endometriosis. The hypothesis that endometriosis risk is driven by low prenatal testosterone, and involves extreme expression of some reproductive phenotypes, is supported by a suite of evidence from genetics, development, endocrinology, morphology and life history. The hypothesis also provides insights into why these two diametric, fitness-reducing disorders are maintained at such high frequencies in human populations. Finally, the hypotheses described and evaluated here lead to numerous testable predictions and have direct implications for the treatment and study of endometriosis. Lay summary: Endometriosis is caused by endometrial tissue outside of the uterus. We explain why and how humans are vulnerable to this disease, and new perspectives on understanding and treating it. Endometriosis shows evidence of being caused in part by relatively low testosterone during fetal development, that 'programs' female reproductive development. By contrast, polycystic ovary syndrome is associated with relatively high testosterone in prenatal development. These two disorders can thus be seen as 'opposite' to one another in their major causes and correlates. Important new insights regarding diagnosis, study and treatment of endometriosis follow from these considerations.

A multidimensional functional fitness score has a stronger association with type 2 diabetes than obesity parameters in cross sectional data

Objectives

We examine here the association of multidimensional functional fitness with type 2 diabetes mellitus (T2DM) as compared to anthropometric indices of obesity such as body mass index (BMI) and waist to hip ratio (WHR) in a sample of Indian population.

Research design and method

We analysed retrospective data of 663 volunteer participants (285 males and 378 females between age 28 and 84), from an exercise clinic in which every participant was required to undergo a health related physical fitness (HRPF) assessment consisting of 15 different tasks examining 8 different aspects of functional fitness.

Results

The odds of being diabetic in the highest quartile of BMI were not significantly higher than that in the lowest quartile in either of the sexes. The odds of being a diabetic in the highest WHR quartile were significantly greater than the lowest quartile in females (OR = 4.54 (1.95, 10.61) as well as in males (OR = 3.81 (1.75, 8.3). In both sexes the odds of being a diabetic were significantly greater in the lowest quartile of HRPF score than the highest (males OR = 10.52 (4.21, 26.13); females OR = 10.50 (3.53, 31.35)). After removing confounding, the predictive power of HRPF was significantly greater than that of WHR. HRPF was negatively correlated with WHR, however for individuals that had contradicting HRPF and WHR based predictions, HRPF was the stronger predictor of T2DM.

Conclusion

The association of multidimensional functional fitness score with type 2 diabetes was significantly stronger than obesity parameters in a cross sectional self-selected sample from an Indian city.

Brown Adipose Tissue Activation by Cold Treatment Ameliorates Polycystic Ovary Syndrome in Rat

Polycystic ovary syndrome (PCOS) is a common endocrine disease accompanied by energetic metabolic imbalance. Because the etiology of PCOS is complex and remains unclear, there is no effective and specific treatment for PCOS. It is often accompanied by various metabolic disorders such as obesity, insulin resistances, and others. Activated brown adipose tissue (BAT) consumes excess energy via thermogenesis, which has positive effects on energy metabolism. Our previous research and that of others indicates that BAT activity is decreased in PCOS patients, and exogenous BAT transplantation can improve PCOS rodents. Notably however, it is difficult to apply this therapeutic strategy in clinical practice. Therapeutic strategies of enhancing endogenous BAT activity and restoring whole-body endocrine homeostasis may be more meaningful for PCOS treatment. In the current study, the dehydroepiandrosterone-induced PCOS rat was exposed to low temperature for 20 days. The results show that cold treatment could reverse acyclicity of the estrous cycle and reduce circulating testosterone and luteinizing hormone in PCOS rats by activating endogenous BAT. It also significantly reduced the expression of steroidogenic enzymes as well as inflammatory factors in the ovaries of PCOS rats. Histological investigations revealed that cold treatment could significantly reduce ovary cystic follicles and increase corpus luteum, indicating that ovulation was recovered to a normal level. Concordant with these results, cold treatment also improved fertility in PCOS rats. Collectively, these findings suggest that cold treatment could be a novel therapeutic strategy for PCOS.

Assessment of the potential role of natural selection in type 2 diabetes and related traits across human continental ancestry groups: comparison of phenotypic with genotypic divergence

AIMS/HYPOTHESIS

Prevalence of type 2 diabetes differs among human ancestry groups, and many hypotheses invoke differential natural selection to account for these differences. We sought to assess the potential role of differential natural selection across major continental ancestry groups for diabetes and related traits, by comparison of genetic and phenotypic differences.

METHODS

This was a cross-sectional comparison among 734 individuals from an urban sample (none of whom was more closely related to another than third-degree relatives), including 83 African Americans, 523 American Indians and 128 European Americans. Participants were not recruited based on diabetes status or other traits. BMI was calculated, and diabetes was diagnosed by a 75 g oral glucose tolerance test. In those with normal glucose tolerance (n = 434), fasting insulin and 30 min post-load insulin, adjusted for 30 min glucose, were taken as measures of insulin resistance and secretion, respectively. Whole exome sequencing was performed, resulting in 97,388 common (minor allele frequency ≥ 5%) variants; the coancestry coefficient (F_ST) was calculated across all markers as a measure of genetic divergence among ancestry groups. The phenotypic divergence index (P_ST) was also calculated from the phenotypic differences and heritability (which was estimated from genetic relatedness calculated empirically across all markers in 761 American Indian participants prior to the exclusion of close relatives). Under evolutionary neutrality, the expectation is P_ST = F_ST, while for traits under differential selection P_ST is expected to be significantly greater than F_ST. A bootstrap procedure was used to test the hypothesis P_ST = F_ST. RESULTS: With adjustment for age and sex, prevalence of type 2 diabetes was 34.0% in American Indians, 12.4% in African Americans and 10.4% in European Americans (p = 2.9 × 10^-10 for difference among groups). Mean BMI was 36.3, 33.4 and 33.0 kg/m², respectively (p = 1.9 × 10^-7). Mean fasting insulin was 63.8, 48.4 and 45.2 pmol/l (p = 9.2 × 10^-5), while mean 30 min insulin was 559.8, 553.5 and 358.8 pmol/l, respectively (p = 5.7 × 10^-8). F_ST across all markers was 0.130, while P_ST for liability to diabetes, adjusted for age and sex, was 0.149 (p = 0.35 for difference with F_ST). P_ST was 0.094 for BMI (p = 0.54), 0.095 for fasting insulin (p = 0.54) and 0.216 (p = 0.18) for 30 min insulin. For type 2 diabetes and BMI, the maximum divergence between populations was observed between American Indians and European Americans (P_ST-MAX = 0.22, p = 0.37, and P_ST-MAX = 0.14, p = 0.61), which suggests that a relatively modest 22% or 14% of the genetic variance, respectively, can potentially be explained by differential selection (assuming the absence of neutral drift).

CONCLUSIONS/INTERPRETATION

These analyses suggest that while type 2 diabetes and related traits differ significantly among continental ancestry groups, the differences are consistent with neutral expectations based on heritability and genetic distances. While these analyses do not exclude a modest role for natural selection, they do not support the hypothesis that differential natural selection is necessary to explain the phenotypic differences among these ancestry groups. Graphical abstract.

Positive selection of type 2 diabetes genotypes - the glycaemic threshold hypothesis

The high prevalence of deleterious polygenic type 2 diabetes (T2D) is a paradox requiring explanation beyond food excess, inactivity and the obesity resulting from positive energy balance. Historically, hunting-foraging and later agrarian communities often manifested a converse negative energy balance due to nutritional deficit and/or high physical energy demand - both potentially resulting in hypoglycaemia. Since hypoglycaemia impairs both reproductive fitness and cognitive function, it is proposed that that by expressing resistance to hypoglycaemia, T2D phenotypes were subject to positive selection. The insulin resistance present in often-associated atherosclerotic cardiovascular disease, metabolic syndrome and polycystic ovarian disease may also explain their frequent coexistence and current prevalence.

Evolutionary origins of polycystic ovary syndrome: An environmental mismatch disorder

Polycystic ovary syndrome (PCOS) is the most common female endocrine disorder and has important evolutionary implications for female reproduction and health. PCOS presents an interesting paradox, as it results in significant anovulation and potential sub-fecundity in industrialized populations, yet it has a surprisingly high prevalence and has a high heritability. In this review, we discuss an overview of PCOS, current diagnostic criteria, associated hormonal pathways and a review of proposed evolutionary hypotheses for the disorder. With a multifactorial etiology that includes ovarian function, metabolism, insulin signaling and multiple genetic risk alleles, PCOS is a complex disorder. We propose that PCOS is a mismatch between previously neutral genetic variants that evolved in physically active subsistence settings that have the potential to become harmful in sedentary industrialized environments. Sedentary obesogenic environments did not exist in ancestral times and exacerbate many of these pathways, resulting in the high prevalence and severity of PCOS today. Overall, the negative impacts of PCOS on reproductive success would likely have been minimal during most of human evolution and unlikely to generate strong selection. Future research and preventative measures should focus on these gene-environment interactions as a form of evolutionary mismatch, particularly in populations that are disproportionately affected by obesity and metabolic disorders.

LAY SUMMARY

The most severe form of polycystic ovary syndrome (PCOS) is likely a result of interactions between genetic predispositions for PCOS and modern obesogenic environments. PCOS would likely have been less severe ancestrally and the fitness reducing effects of PCOS seen today are likely a novel product of sedentary, urban environments.

Is polycystic ovary syndrome a 20th Century phenomenon?

Polycystic ovary syndrome (PCOS) affects around 10% of women of reproductive age and is most common in developed countries. The aetiology of PCOS is not completely understood. Current evidence suggests that the syndrome results from a genetic predisposition interacting with developmental events during fetal or perinatal life that together increase susceptibility in some individuals. This implies that environmental factors influence the initiation of PCOS in the fetus or infant, either directly or via the mother. PCOS is often considered to be an ancient disorder but there is no direct proof of this in the medical or historic record. One of the cardinal features, polycystic ovaries, was first described only in the early 1900s, despite reports of many thousands of autopsies recorded earlier. This conundrum could be explained by postulating that polycystic ovaries were rare before the 1900s and have become more common over the last 100 years. The hypothesis that PCOS is a syndrome of the 20th Century would eliminate the need to explain the paradox of why there exists a genetic predisposition to subfertility syndrome.

An Evolutionary Perspective on the Obesity Epidemic

An evolutionary approach to obesity involves a genomic/anthropological dimension. For 1.8 Myr the lifestyle of hunter-gatherers (HGs) comprised intense physical activity and a high-protein/low-carbohydrate diet. Genomes of HGs were adapted to low insulin sensitivity. When the agrarian epoch began a new 'farmer diet' high in carbohydrates (CHO) emerged. Owing to periodic famines, the genome may not have adapted; they preserved a HG genome. Ever since the industrial revolution our genome is adapting rapidly to a CHO-rich diet. Individuals with preserved HG genome develop obesity at age 4-8 years and need a low-CHO diet. By contrast, those with a farmer genome become obese in infancy; they need a low-calorie diet. This knowledge prompts exploration of the two genomes and their clinical presentations.

Bi-stability in type 2 diabetes mellitus multi-organ signalling network

Type 2 diabetes mellitus (T2DM) is believed to be irreversible although no component of the pathophysiology is irreversible. We show here with a network model that the apparent irreversibility is contributed by the structure of the network of inter-organ signalling. A network model comprising all known inter-organ signals in T2DM showed bi-stability with one insulin sensitive and one insulin resistant attractor. The bi-stability was made robust by multiple positive feedback loops suggesting an evolved allostatic system rather than a homeostatic system. In the absence of the complete network, impaired insulin signalling alone failed to give a stable insulin resistant or hyperglycemic state. The model made a number of correlational predictions many of which were validated by empirical data. The current treatment practice targeting obesity, insulin resistance, beta cell function and normalization of plasma glucose failed to reverse T2DM in the model. However certain behavioural and neuro-endocrine interventions ensured a reversal. These results suggest novel prevention and treatment approaches which need to be tested empirically.

How much variance in insulin resistance is explained by obesity?

Background: Obesity is believed to be the major cause of insulin resistance, although many other obesity-independent signals are shown to affect insulin sensitivity.Aim: We address the degree to which variation in insulin resistance is explained by morphometric and biochemical measures of obesity.Methods: PubMed and Google Scholar were searched for epidemiological studies published between 1994 and 2015 that report correlations between at least one measure of obesity and that of insulin resistance.Results: A total of 63 studies satisfied inclusion criteria. Frequency distribution of coefficients of determination between morphometric measures of obesity and insulin resistance was skewed with the mode being less than 10%, class and median being 17.3%. Plasma leptin concentration, but not plasma non-esterified fatty acid level, was better correlated with insulin resistance, the median variance explained being 33.29%. Morphometric measures alone had a median variance explained of 16%. Ethnicity explained part of the variance across studies with the correlation being significantly poorer in Asians.Conclusion: The extremely limited predictive power of morphometric and biochemical measures of obesity suggests that more research needs to focus on the obesity-independent signals that affect insulin sensitivity as well as leptin expression.

Developmental influences on fertility decisions by women: an evolutionary perspective

Developmental environments are crucial for shaping our life course. Elements of the early social and biological environments have been consistently associated with reproduction in humans. To date, a strong focus has been on the relationship between early stress, earlier menarche and first child birth in women. These associations, found predominately in high-income countries, have been usefully interpreted within life-history theory frameworks. Fertility, on the other hand--a missing link between an individual's early environment, reproductive strategy and fitness--has received little attention. Here, we synthesize this literature by examining the associations between early adversity, age at menarche and fertility and fecundity in women. We examine the evidence that potential mechanisms such as birth weight, childhood body composition, risky health behaviours and developmental influences on attractiveness link the early environment and fecundity and fertility. The evidence that menarche is associated with fertility and fecundity is good. Currently, owing to the small number of correlational studies and mixed methodologies, the evidence that early adversity predicts fecundity and fertility is not conclusive. This area of research is in its infancy; studies examining early adversity and adult fertility decisions that can also examine likely biological, social and psychological pathways present opportunities for future fertility research.

Identification of polycystic ovary syndrome potential drug targets based on pathobiological similarity in the protein-protein interaction network

Polycystic ovary syndrome (PCOS) is one of the most common endocrinological disorders in reproductive aged women. PCOS and Type 2 Diabetes (T2D) are closely linked in multiple levels and possess high pathobiological similarity. Here, we put forward a new computational approach based on the pathobiological similarity to identify PCOS potential drug target modules (PPDT-Modules) and PCOS potential drug targets in the protein-protein interaction network (PPIN). From the systems level and biological background, 1 PPDT-Module and 22 PCOS potential drug targets were identified, 21 of which were verified by literatures to be associated with the pathogenesis of PCOS. 42 drugs targeting to 13 PCOS potential drug targets were investigated experimentally or clinically for PCOS. Evaluated by independent datasets, the whole PPDT-Module and 22 PCOS potential drug targets could not only reveal the drug response, but also distinguish the statuses between normal and disease. Our identified PPDT-Module and PCOS potential drug targets would shed light on the treatment of PCOS. And our approach would provide valuable insights to research on the pathogenesis and drug response of other diseases.

Single-Nucleotide Polymorphism on Exon 17 of Insulin Receptor Gene Influences Insulin Resistance in PCOS: A Pilot Study on North Indian Women

Polycystic ovarian syndrome (PCOS), a major cause of infertility, is also strongly associated with insulin resistance. Defects in insulin receptor signaling are considered as one of the major molecular pathogeneses for insulin resistance. To investigate the possible mechanism of this signaling defect at genetic level, single-nucleotide polymorphism (SNP) [His 1085 C/T] at the exon 17 of insulin receptor gene (INSR) was studied in this pilot study. Polymerase chain reaction was performed on leucocytic DNA of women diagnosed with PCOS, selected from the outpatient department of Safdarjung Hospital, New Delhi, using suitable primer to amplify a region on INSR. An equal number of age-matched healthy women were selected as controls. SNP analysis was performed with restriction enzyme length polymorphism technique using Pm II enzyme. Serum insulin level was measured by ELISA kit and HOMA-IR was calculated mathematically. A higher frequency of the CC genotype was observed in PCOS women than in controls. Also, HOMA-IR, a tool for estimating insulin resistance, was significantly high in PCOS women with the CC genotype. C1008T SNP at exon 17 of INSR is associated with insulin resistance in Indian women with PCOS. Presence of CC genotype (C1085T) could be developed as a marker for insulin resistance and metabolic complications in PCOS women.

Pacific Populations, Metabolic Disease and 'Just-So Stories': A Critique of the 'Thrifty Genotype' Hypothesis in Oceania

Pacific populations have long been observed to suffer a high burden of metabolic disease, including obesity, type 2 diabetes and gout. The 'Thrifty Genotype' hypothesis has frequently been used to explain this high prevalence of disease. Here, the 'Thrifty Genotype' hypothesis and the evolutionary background of Pacific populations are examined. We question its relevance not only in the Pacific region but more generally. Not only has the hypothesis not been explicitly tested, but most archaeological and anthropological data from the Pacific fundamentally do not support its application.

Metabolomics reveals impaired maturation of HDL particles in adolescents with hyperinsulinaemic androgen excess

Hyperinsulinaemic androgen excess (HIAE) in prepubertal and pubertal girls usually precedes a broader pathological phenotype in adulthood that is associated with anovulatory infertility, metabolic syndrome and type 2 diabetes. The metabolic derangements that determine these long-term health risks remain to be clarified. Here we use NMR and MS-based metabolomics to show that serum levels of methionine sulfoxide in HIAE girls are an indicator of the degree of oxidation of methionine-148 residue in apolipoprotein-A1. Oxidation of apo-A1 in methionine-148, in turn, leads to an impaired maturation of high-density lipoproteins (HDL) that is reflected in a decline of large HDL particles. Notably, such metabolic alterations occur in the absence of impaired glucose tolerance, hyperglycemia and hypertriglyceridemia, and were partially restored after 18 months of treatment with a low-dose combination of pioglitazone, metformin and flutamide.

CYP17 genotype modifies the impact of anthropometric variation on salivary estradiol in healthy women

Several studies demonstrate that human ovarian function is responsive to the energetic environment, which has led to the development of theoretical models that explain this phenomenon. Although many genes are involved in ovarian hormone production, the possibility that genetic polymorphism may affect ovarian response to energetic conditions has not been considered. Cytochrome P450c17α is an enzyme that produces androgen precursors used to make estrogens during ovarian steroidogenesis, and is encoded by the CYP17 gene. A functionally significant variant within the promoter region of CYP17 has been linked to variation in steroid production, and some evidence suggests that this polymorphism could alter transcription of CYP17 in an insulin-dependent manner. We tested the hypothesis that the CYP17 variant affected the relationship between anthropometric measurements and salivary estradiol in healthy women in the United States (n = 28). PCR-RLFP analysis was used to genotype women for the genetic variant, and estradiol was assayed from saliva by EIA. Moderated regression analysis of these preliminary data revealed a significant interaction between waist-to-hip ratio and CYP17 genotype (P = 0.004). Our study provides evidence that gene-environment interactions should be considered in future adaptive models for human ovarian function. Moreover, our results stand to illuminate possible associations between this genetic variant and reproductive disease.

Hyperinsulinaemic androgen excess in adolescent girls

Hyperinsulinaemic androgen excess is the most common cause of hirsutism, acne and menstrual irregularity in adolescent girls. Here, we propose that the disorder frequently originates from an absolute or relative excess of lipids in adipose tissue, and from associated changes in insulin sensitivity, gonadotropin secretion and ovarian androgen release. Girls from populations with genotypes attuned to nutritionally harsh conditions seem to be particularly vulnerable to the development of hyperinsulinaemic androgen excess in today's obesogenic environment. We propose that hirsutism, hyperandrogenaemia and menstrual irregularity (≥2 years after menarche) is used as a diagnostic triad for the disorder. No pharmacological therapy has been approved for girls with androgen excess; however, lifestyle intervention is essential to reduce adiposity. In girls without obesity who are not sexually active, insulin sensitization has more broadly normalizing effects than estradiol-progestogen combinations. The early recognition of girls at risk of developing hyperinsulinaemic androgen excess might enable prevention in childhood.

Dairy products in global public health

Intakes of dairy produce show enormous diversity between regions, cultures, and individuals around the world. At the geographic level, intake maps closely onto the distribution of lactase persistence (LP), a genetic trait that allows milk to be consumed beyond the weaning period without gastrointestinal side effects. The LP trait has been independently selected at least 4 times and is under rapid positive selection, which shows that dairy consumption has positive survival benefits. For people lacking the LP trait, the fermentation of milk into yogurt and related products (a process known for ≥8500 y) aids milk digestion through the breakdown of some lactose and the provision of β-galactosidase, which remains active in the gastrointestinal tract. In global ecologic comparisons, milk and dairy intakes are strongly associated with adult height, and many international advisory bodies recommend the consumption of 400-500 mL milk equivalents/d. There are very few countries where such high intakes are met, and in populations in whom intakes are much lower there is evidence of adaptations that help to maintain bone health with surprisingly low intakes. Despite concerns that the high-saturated-fat content of full-fat dairy products would promote heart disease, recent meta-analyses show that dairy consumption is neutral or beneficial for weight control, coronary disease, diabetes, hypertension, and most cancers.

The hidden cost of moving up: type 2 diabetes and the escape from persistent poverty in the American South

OBJECTIVES

The paper tests the thrifty phenotype hypothesis, according to which nonharmonious growth trajectories are costly for adult health.

METHODS

The American surge in the prevalence of type 2 diabetes is concentrated in the South, a region characterized by a long history of poverty followed by rapid economic growth beginning in the 1960s. Civil rights legislation further accelerated income growth for African-Americans in the region. The paper investigates the hypothesis by using per capita income at the state level as a proxy for net nutritional conditions.

RESULTS

Regressions at the state level explain 56% of the variation in the prevalence rate of type 2 diabetes in 2009 using two explanatory variables: the ratio of per capita income in 1980 to that in 1950 and the share of the population that was African-American. The paper discusses ways that rapid economic growth may have translated into weight gain and type 2 diabetes.

CONCLUSIONS

If the thrifty phenotype hypothesis is correct, future rates in the prevalence of type 2 diabetes are predictable based on income history. The forecast for rapidly developing countries such as India and China are ominous.

The Polycystic Ovary Syndrome and recent human evolution

The Polycystic Ovary Syndrome (PCOS) is a complex endocrine disorder characterised both by reproductive and metabolic disturbance, and is the most common cause globally of ovarian infertility. It is also a familial polygenic condition, linked genetically to both Type 2 diabetes and the metabolic syndrome. The striking evolutionary paradox of this prominent genetically-based condition, which impairs fertility, is that not only should it have diminished in prevalence, but it should have done so rapidly - unless there has been some form of balancing selection. The emerging discipline of evolutionary medicine can provide important insights into the causes and patterns of occurrence of common diseases such as PCOS. In this paper we review the impacts of PCOS on infertility, fecundability and lifetime reproductive success and then critically appraise published hypotheses about the evolutionary origins of PCOS and related conditions.

Plasma selenium levels in Turkish women with polycystic ovary syndrome

OBJECTIVE(S)

To evaluate selenium (Se) levels in serum and their relation with hyperandrogenism and insulin resistance (IR) in women with polycystic ovary syndrome (PCOS) and in control subjects.

STUDY DESIGN

Women with any gynecological problem who presented to the Kahramanmaras Sutcuimam University Medical Faculty Gynecology and Obstetric Outpatient Clinic were invited to participate. Group 1 consisted of 36 cases with a diagnosis of PCOS according to the 2003 Rotterdam Consensus Criteria, and Group 2 (control group) consisted of 33 age- and BMI-matched healthy women. In all cases, serum total testosterone (tT), dihydroepiandrostenedione-sulfate (DHEAS), follicle stimulating hormone (FSH), luteinizing hormone (LH), estradiol (E2), insulin, glucose (mg/dL), total cholesterol (TC) (mg/dL), high density lipoprotein-cholesterol (HDL-C) (mg/dL), low density lipoprotein-cholesterol (LDL-C) (mg/dL), triglyceride (TG) (mg/dL) and Se levels were measured.

RESULTS

The level of FSH was significantly lower, and the levels of LH, E2, tT, and DHEAS were significantly higher in group 1 than in group 2 (p<0.05). The hirsutism score was significantly higher among PCOS women compared to the control group (p<0.05). Although insulin levels and HOMA-IR were markedly increased in the PCOS group compared to the control group, the differences were not significant (p>0.05). The plasma Se level was significantly lower in PCOS women compared to the control group (p<0.05). When we combined the all women in two groups, regarding them as one group (combined group, n=69), a negative correlation between Se and LH and tT was present (p<0.05).

CONCLUSION(S)

Our results show decreased plasma concentrations of Se and a negative correlation between Se and LH, tT in women with PCOS. These results indicate that Se may play a role in the pathogenesis of PCOS related with hyperandrogenism.

Genome-wide association study identifies GYS2 as a novel genetic factor for polycystic ovary syndrome through obesity-related condition

To investigate the role of genetic predisposition in the pathogenesis of polycystic ovary syndrome (PCOS) in relation to obesity, we performed a genome-wide association study of PCOS in Koreans (n=1741). PCOS is a heterogeneous endocrinal disorder of uncertain etiology. Obesity is one of the well-known risk factors for PCOS. Genome-wide association study. Women with or without PCOS. A total of 1881 samples were genotyped using Illumina HumanOmni1 Quad v1 and processed by R packages. The PCOS patients were divided into two subgroups according to PCOS diagnostic criteria (Rotterdam and National Institutes of Health (NIH)). For PCOS-associated loci in the two definitions, we successfully confirmed significant associations of GYS2 for body mass index in the discovery stage. We further replicated pleiotropic associations of GYS2 in a childhood obesity study (n=482) and in a gestational diabetes study (n=1710), respectively. Our study provides a preliminary framework upon diverse genetic effects underlying PCOS in Korean women. A newly identified GYS2 gene as a predisposing factor of PCOS might expand understanding of the biological pathways in metabolic and endocrine regulation.

Nothing in medicine makes sense, except in the light of evolution

The practice of medicine is a fruitful marriage of classic diagnostic and healing arts with modern advancements in many relevant sciences. The scientific aspects of medicine are rooted in understanding the biology of our species and those of other organisms that interact with us in health and disease. Thus, it is reasonable to paraphrase Dobzhansky, stating that, "nothing in the biological aspects of medicine makes sense except in the light of evolution." However, the art and science of medicine are also rooted in the unusual cognitive abilities of humans and the cultural evolutionary processes arising. This explains the rather bold and inclusive title of this essay. The near complete absence of evolution in medical school curricula is a historical anomaly that needs correction. Otherwise, we will continue to train generations of physicians who lack understanding of some fundamental principles that should guide both medical practice and research. I here recount my attempts to correct this deficiency at my own medical school and the lessons learned. I also attempt to summarize what I teach in the limited amount of time allowed for the purpose. Particular attention is given to the value of comparing human physiology and disease with those of other closely related species. There is a long way to go before the teaching of evolution can be placed in its rightful context within the medical curriculum. However, the trend is in the right direction. Let us aim for a day when an essay like this will no longer be relevant.

Low fertility and the risk of type 2 diabetes in women

BACKGROUND

Fertility problems are frequently followed by early menopause, and early menopause has been associated with increased risk of type 2 diabetes (T2D). Thus far, it is unknown whether low fertility is independently associated with future T2D risk.

METHODS

We assessed the association between measures of low fertility and T2D in the Prospect-European Prospective Investigation into Cancer and Nutrition (EPIC) cohort of 17,357 Dutch women, aged 49-70 years at baseline using Cox proportional hazards models, adjusted for various confounders. To investigate whether BMI and waist circumference influence the observed associations, analyses were additionally adjusted for these variables.

RESULTS

At baseline, 332 women had T2D. During a mean follow-up of 9.1 ± 3.6 years, 535 T2D cases occurred. Out of 15,707 Prospect-EPIC women who wanted to get pregnant, 1940 consulted a physician for fertility problems and 700 remained childless. No relation was found between consulting a physician for fertility problems or nulliparity and T2D risk. Of all women who wanted to get pregnant, 3946 (25.1%) had one or more miscarriages, with an average of 1.4 (± 0.9) miscarriages and a maximum of 10 miscarriages. Women who had one or more miscarriage showed the same risk for T2D as women who had no miscarriage. Also, none of the other measures of low fertility were associated with increased risk for T2D.

CONCLUSIONS

Generally, measures of low fertility were not independently associated with a risk of T2D in a cohort of 17 357 Dutch women.

Can Thrifty Gene(s) or Predictive Fetal Programming for Thriftiness Lead to Obesity?

Obesity and related disorders are thought to have their roots in metabolic "thriftiness" that evolved to combat periodic starvation. The association of low birth weight with obesity in later life caused a shift in the concept from thrifty gene to thrifty phenotype or anticipatory fetal programming. The assumption of thriftiness is implicit in obesity research. We examine here, with the help of a mathematical model, the conditions for evolution of thrifty genes or fetal programming for thriftiness. The model suggests that a thrifty gene cannot exist in a stable polymorphic state in a population. The conditions for evolution of thrifty fetal programming are restricted if the correlation between intrauterine and lifetime conditions is poor. Such a correlation is not observed in natural courses of famine. If there is fetal programming for thriftiness, it could have evolved in anticipation of social factors affecting nutrition that can result in a positive correlation.

Polycystic ovary syndrome: etiology, pathogenesis and diagnosis

Polycystic ovary syndrome (PCOS) is the most common endocrinopathy in women of reproductive age, with a prevalence of up to 10%. Various diagnostic criteria have been proposed, generally centered around the features of hyperandrogenism and/or hyperandrogenemia, oligo-ovulation and polycystic ovarian morphology. Insulin resistance is present in a majority of cases, with compensatory hyperinsulinemia contributing to hyperandrogenism via stimulation of ovarian androgen secretion and inhibition of hepatic sex hormone-binding globulin production. Adipose tissue dysfunction has been implicated as a contributor to the insulin resistance observed in PCOS. Environmental and genetic factors also have a role in the development of PCOS. The syndrome is associated with numerous morbidities, including infertility, obstetrical complications, type 2 diabetes mellitus, cardiovascular disease, and mood and eating disorders. Despite these morbidities, PCOS may be common in our society owing to evolutionary advantages of the syndrome in ancient times, including smaller family sizes, reduced exposure to childbirth-related mortality, increased muscle mass and greater capacity to store energy. The diagnosis of PCOS hinges on establishing key features while ruling out other hyperandrogenic or oligo-ovulatory disorders. Treatment is focused on the goals of ameliorating hyperandrogenic symptoms, inducing ovulation and preventing cardiometabolic complications.

Beyond thriftiness: independent and interactive effects of genetic and dietary factors on variations in fat deposition and distribution across populations

The thrifty genotype hypothesis initiated speculation that feast and famine cycling throughout history may have led to group-specific alterations of the human genome, thereby augmenting the capacity for excessive fat mass accrual when immersed in the modern-day obesogenic environment. Contemporary work, however, suggests alternative mechanisms influencing fuel utilization and subsequent tissue partitioning to be more relevant in the etiology of population-based variation in adipose storage. The objective of this study was to evaluate the independent and interactive contribution of ancestral admixture as a proxy for population-based genetic variation and diet on adipose tissue deposition and distribution in peripubertal children and to identify differences in racial/ethnic and sex groups. Two-hundred seventy-eight children (53% male) aged 7-12 years, categorized by parental self-report as African- (n = 91), European- (n = 110), or Hispanic American (n = 77), participated. Ancestral genetic admixture was estimated using 140 ancestry informative markers. Body composition was evaluated by dual-energy X-ray absorptiometry; energy expenditure by indirect calorimetry and accelerometry; and diet by 24-h-recall. Admixture independently contributed to all adiposity parameters; i.e., estimates of European and Amerindian ancestries were positively associated with all adiposity parameters, whereas African genetic admixture was inversely associated with adiposity. In boys, energy intake was associated with adiposity, irrespective of macronutrient profile, whereas in girls, the relationship was mediated by carbohydrate. We also observed moderating effects of energy balance/fuel utilization of the interaction between ancestral genetic admixture and diet. Interactive effects of genetic and non-genetic factors alter metabolic pathways and underlie some of the present population-based differences in fat storage.

The price of protein: combining evolutionary and economic analysis to understand excessive energy consumption

Excessive weight gain appears, thermodynamically at least, straightforward: growing energy intake and/or falling energy expenditure create an energetic surplus, resulting in fat accumulation. The situation is, however, far more complex, with genetic, physiological, social, psychological and economic factors all implicated. Thus the causes of excessive weight gain remain difficult to disentangle. We combine two recent developments from different areas of nutrition research: the study of food prices in relation to energy content and the hypothesis that an evolved propensity to regulate protein intake more strongly than non-protein calories exerts powerful leverage on overall energy intake. We partition the energy content of a range of common supermarket foods, and show that increasing overall energy content only modestly raises the cost of foods, largely as a result of macronutrients having very different costs. Higher food prices are associated with higher protein content and lower carbohydrate content, whereas fat content was not significantly associated with food price. We show that the differential costs of energy from protein and carbohydrates may bias consumers towards diets high in carbohydrate energy, leading them to consume excessive energy to meet their dietary protein needs. We review evidence from physiology, evolution and economics that support our suggestion.

Polycystic ovary syndrome: an ancient disorder?

Polycystic ovary syndrome (PCOS) appears to be an ancient disorder, which has persisted in human evolution despite reduced fecundity because of the benefits to affected women such as greater sturdiness and improved energy utilization, a rearing advantage for their children and kin, and a reduction in the risk of perinatal mortality. This raises the possibility that gene variants that are eventually found to be associated with PCOS will be similar across ethnic groups and races.

Sex differences in obesity associated with total fertility rate

The identification of biological and ecological factors that contribute to obesity may help in combating the spreading obesity crisis. Sex differences in obesity rates are particularly poorly understood. Here we show that the strong female bias in obesity in many countries is associated with high total fertility rate, which is well known to be correlated with factors such as low average income, infant mortality and female education. We also document effects of reduced access to contraception and increased inequality of income among households on obesity rates. These results are consistent with studies that implicate reproduction as a risk factor for obesity in women and that suggest the effects of reproduction interact with socioeconomic and educational factors. We discuss our results in the light of recent research in dietary ecology and the suggestion that insulin resistance during pregnancy is due to historic adaptation to protect the developing foetus during famine. Increased access to contraception and education in countries with high total fertility rate might have the additional benefit of reducing the rates of obesity in women.

Novel therapeutic concepts: the epidemic of cardiovascular disease in the developing world: global implications

The epidemic of cardiovascular disease (CVD) is a global phenomenon, and the magnitude of its increase in incidence and prevalence in low- and middle-income countries (LIMIC) has potentially major implications for those high-income countries that characterize much of the developed world. Cardiovascular disease remains the leading cause of death in the world and approximately 80% of all cardiovascular-related deaths occur in LIMIC and at a younger age in comparison to high-income countries. The economic impact in regard to loss of productive years of life and the need to divert scarce resources to tertiary care is substantial. The 'epidemiologic transition' provides a useful framework for understanding changes in the patterns of disease as a result of societal and socioeconomic developments in different countries and regions of the world. A burning but as yet unanswered question is whether gains made over the last four decades in reducing cardiovascular mortality in high-income countries will be offset by changes in risk factor profiles, and in particular obesity and diabetes. Much of the population attributable risk of myocardial infarction is accountable on the basis of nine modifiable traditional risk factors, irrespective of geography. Developing societies are faced with a hostile cardiovascular environment, characterized by changes in diet, exercise, the effects of tobacco, socioeconomic stressors, and economic constraints at both the national and personal level in addition to exposure to potential novel risk factors and perhaps a genetic or programmed foetal vulnerability to CVD in later life. There are major challenges for primary and secondary prevention including lack of data, limited national resources, and the lack of prediction models in certain populations. There are two major approaches to prevention: public health/community-based strategies and clinic-based with a targeted approach to high-risk patients and combinations of these. There are concerns that in comparison with communicable diseases, cardiovascular and chronic diseases have a relatively low priority in the global health agenda and that this requires additional emphasis. The human race has had long experience and a fine tradition in surviving adversity, but we now face a task for which we have little experience, the task of surviving prosperity Alan Gregg 1890-1957, Rockefeller Foundation.