Contribution of allelic variability in prostate specific antigen (PSA) & androgen receptor (AR) genes to serum PSA levels in men with prostate cancer.

BACKGROUND & OBJECTIVES: Wide variability in serum prostate specific antigen (PSA) levels exists in malignant conditions of the prostate. PSA is expressed in normal range in 20 to 25 per cent of prostate cancer cases even in presence of high grade Gleason score. This study was aimed to assess the influence of genetic variants exhibited by PSA and androgen receptor (AR) genes towards the variable expression of PSA in prostate cancer. METHODS: Pre-treatment serum PSA levels from 101 prostate cancer cases were retrieved from medical record. PSA genotype analysis in promoter region and AR gene microsatellite Cytosine/Adenine/Guanine (CAG) repeat analysis in exon 1 region was performed using DNA sequencing and fragment analysis techniques. RESULTS: A total of seven single nucleotide polymorphisms (SNPs) in the PSA promoter region were noted. Only two SNPs viz., 158G/A (P<0.001) in the proximal promoter region and -3845G/A (P<0.001) in enhancer region showed significant association with serum PSA levels. The carriers of homozygous GG genotype (P<0.001) at both of these polymorphic sites showed higher expression of PSA whereas homozygous AA genotype (P<0.001) carriers demonstrated lower PSA levels. The combination effect of PSA genotypes along with stratified AR CAG repeats lengths (long, intermediate and short) was also studied. The homozygous GG genotype along with AR long CAG repeats and homozygous AA genotype along with AR short CAG repeats at position -3845 and -158 showed strong interaction and thus influenced serum PSA levels. INTERPRETATION & CONCLUSIONS: The genetic variants exhibited by PSA gene at positions -3845G/A and -158G/A may be accountable towards wide variability of serum PSA levels in prostate cancer. Also the preferential binding of G and A alleles at these polymorphic sites along with AR long and short CAG repeats may contribute towards PSA expression.

Mutational analysis of methyl-CpG binding protein 2 (MECP2) gene in Indian cases of Rett syndrome.

Rett syndrome (RTT) is an X-linked postnatal neurological disorder, primarily affecting females and characterized by regression, epilepsy, stereotypical hand movements, and motor abnormalities. Its prevalence is about 1 in 10,000 female births. RTT is caused by mutations within methyl CpG-binding protein 2 (MECP2) gene. Over 200 individual nucleotide changes in the gene, which cause pathogenic mutations, have been reported; however, eight most commonly occurring missense and nonsense mutations account for almost 70% of all mutations. RTT cases have also been reported from India. The phenotype (classical and atypical inclusive) has many differentials. However, a genetically based confirmed diagnosis would help in management and counseling. In this pilot study we have analyzed MECP2 mutations in ten Indian sporadic patients diagnosed clinically as having RTT. Two mutations and one novel variant in MECP2 have been detected. Missense mutations p.R133C and c.806delG have been detected. The missence mutation p.R133C was the part of eight hotspots reported in Rett patients. This patient met all the essential criteria except delayed onset of regression. The other c.806delG mutation positive patient also fulfilled all the obligatory criteria of classical RTT. Another clinically atypical Rett patient showed a novel mutation p.C339S in MECP2 gene. The preliminary result necessitates a large-scale study of RTT patients to determine more precisely the influence of MECP2 mutations in Indian patients and their correlation with clinical phenotypes.

Elucidation of regulatory mechanisms revealed by human promoter sequence analysis of genes co-expressed in forskolin-treated theca cells in PCOS.

PURPOSE: Polycystic ovary syndrome (PCOS) is a reproductive endocrinopathy and is the most common cause of anovulatory infertility in women of reproductive age group. In PCOS research, there have been several reports which have shown the differential expression of genes from various tissue and cell types. However, little information can be gained about the regulation of these genes from the microarray data itself. Therefore, with the assumption that co-expression can also imply co-regulation in high-throughput gene expression studies, we investigated the role of various transcription factors by elucidating their binding sites (TFBSs) in these genes. METHODS: For this purpose, a group of 40 genes altered in a forskolin-treated PCOS gene expression study in theca cells were analyzed using in silico tools. 2,000 bp of the upstream region were extracted from all these genes, and the PAINT suite of programs was used to identify over-represented TFBSs in these genes. RESULTS: We identified three different TFBSs which were over-represented as compared with a human promoter background model. These three transcription factors (TFs) are Oct, HFH, and neuron-restrictive silencing factor. Each of these three TFs and their compatible members can be implicated in the pathogenesis of PCOS, as described in detail in this article. CONCLUSIONS: These factors might reveal a new insight into the complex pathogenesis of PCOS especially with respect to cAMP pathway.

Characterization of human immunodeficiency virus (HIV1C) variants in peripheral blood mononuclear cells and spermatozoa.

The presence of distinct viral variants in different cells and secretions of the same person influences the transmission of HIV as well as the response to the host defense and to therapy. Sperm-associated virus is also a risk factor for sexual transmission of HIV. Characterization of the C2-V3 region of HIV1C env gene by the Heteroduplex Mobility Assay (HMA) and sequencing demonstrated the presence of distinct variants in the peripheral blood mononuclear cells (PBMCs) and the sperm of the same individual (n = 6). The translated amino acid sequences of HIV variants in the PBMCs of all the study participants (n = 12) and spermatozoa of the six participants characterized showed the presence of distinct variants with different numbers of N-linked glycosylation (NLG) sites. Infectivity of PBMCs of these persons by co-culture with PBMCs from healthy individuals as detected by the p24 levels in the culture supernatant did not show a correlation with the blood plasma viral load. Interestingly, the infectivity of the sperm samples from four of the five individuals showed positive correlation with the viral load in seminal plasma. The study suggests the presence of distinct viral variants in the sperm and PBMCs of the same person with differential infectivity, and the NLG sites may be associated with the affinity of HIV to receptor/co-receptor usages as well as affinity toward neutralizing antibodies which may influence the risk of sperm associated virus in sexual transmission of HIV and transmit the virus further to distal cells.

Molecular & genetic factors contributing to insulin resistance in polycystic ovary syndrome.

Polycystic ovary syndrome (PCOS) is the most common endocrine disorder of unknown etiology. Insulin resistance is very common and plays a central pathogenic role in PCOS. During last decade several studies have been conducted to understand the mechanisms contributing to the state of insulin resistance and insulin-induced hyperandrogenemia in PCOS. Insulin signaling pathways have been dissected in different insulin responsive tissues such as skeletal muscles, adipose tissues, fibroblasts as well as ovaries to elucidate the mechanism. These studies suggest a post receptor signaling defect where metabolic action of insulin is affected but not the steroidogenic and mitogenic actions. Despite advancement in these studies gaps exist in our understanding of the mechanism of insulin resistance as well as insulin- induced steroidogenesis in PCOS. The syndrome is now considered as a complex multigenic disorder. Efforts are ongoing to dissect the variants of genes from multiple logical pathways which are involved in pathophysiology of the syndrome. But still today no gene has been emerged as universally accepted susceptibility gene for PCOS. This review briefly describes the lacunae along with the current status of molecular events underlying insulin resistance and the contribution of insulin signaling pathway genes in pathogenesis of PCOS along with future researchable areas.

Obesity and polycystic ovary syndrome: association with androgens, leptin and its genotypes.

Obesity and hyperandrogenaemia are key features of polycystic ovary syndrome (PCOS). The aim of this study was to investigate whether leptin and androgens are associated with obesity in PCOS subjects and identify whether there exist any genetic alterations in leptin gene in women with PCOS. The results reveal that leptin levels are elevated in women with PCOS and associate with BMI. However, irrespective of the obesity status leptin levels are higher in PCOS cases indicating that increased BMI/obesity may not be the only factor contributing to elevated levels of leptin. With regard to testosterone and androstenedione, the levels were increased in obese individuals irrespective of PCOS status. No correlation between leptin and androstenedione or testosterone was observed in controls and PCOS subjects. The single-nucleotide polymorphism G19A detected in the untranslated exon 1 of leptin gene was not associated with PCOS and does not contribute to elevated levels of leptin. The results overall suggest that androgen and leptin levels are increased in PCOS and obesity. It demonstrates that obesity is a confounding factor for hyperandrogenaemia irrespective of their PCOS status. The study rules out role of obesity status and leptin genotype in increase in leptin levels observed in PCOS cases.

Longer CAG repeat length in the androgen receptor gene is associated with premature ovarian failure.

BACKGROUND: Premature ovarian failure (POF) is a disorder characterized by lack of ovulation and elevated serum gonadotrophin levels before the age of 40 years. The cause of POF in most cases is unknown. As mice lacking the Androgen receptor (Ar) gene reportedly have a POF-like phenotype, we hypothesize that, variations in the AR gene maybe one of the causative factors for POF in humans. Thus the objective of the study is to evaluate the number of CAG repeats in exon 1 of the AR gene in non-familial, non-syndromic cases of POF. METHODS: A clinic-based case-control study. Seventy-eight patients with non-familial, non-syndromic POF, and 90 controls were recruited to investigate the CAG repeat numbers in exon 1 of the AR gene by PCR and Gene Scan analysis. RESULTS: The mean CAG repeat length in exon 1 of the AR gene of women with POF was 23.6 +/- 3.8, which was significantly higher than controls (20.08 +/- 3.45) (P < 0.001). The biallelic mean CAG repeat ranged from 11 to 32 in the control women, compared to 16 to 30 in the POF patients. The 22 CAG repeat allele followed by the 24 CAG repeat allele was found to be at highest frequency (15.38 and 12.8%) in POF cases, although the 19 CAG repeat allele was observed at highest frequency (12.2%) in controls. CONCLUSIONS: The observation suggests that the CAG repeat length is increased in women with POF as compared with controls, and may be pathogenic for POF, at least in a subset of Indian women.

A novel 9-bp insertion detected in steroid 21-hydroxylase gene (CYP21A2): prediction of its structural and functional implications by computational methods.

BACKGROUND: Steroid 21-hydroxylase deficiency is the most common cause of congenital adrenal hyperplasia (CAH). Detection of underlying mutations in CYP21A2 gene encoding steroid 21-hydroxylase enzyme is helpful both for confirmation of diagnosis and management of CAH patients. Here we report a novel 9-bp insertion in CYP21A2 gene and its structural and functional consequences on P450c21 protein by molecular modeling and molecular dynamics simulations methods. METHODS: A 30-day-old child was referred to our laboratory for molecular diagnosis of CAH. Sequencing of the entire CYP21A2 gene revealed a novel insertion (duplication) of 9-bp in exon 2 of one allele and a well-known mutation I172N in exon 4 of other allele. Molecular modeling and simulation studies were carried out to understand the plausible structural and functional implications caused by the novel mutation. RESULTS: Insertion of the nine bases in exon 2 resulted in addition of three valine residues at codon 71 of the P450c21 protein. Molecular dynamics simulations revealed that the mutant exhibits a faster unfolding kinetics and an overall destabilization of the structure due to the triple valine insertion was also observed. CONCLUSION: The novel 9-bp insertion in exon 2 of CYP21A2 genesignificantly lowers the structural stability of P450c21 thereby leading to the probable loss of its function.

CGG repeat sizing in the FMR1 gene in Indian women with premature ovarian failure.

The CGG repeat stretch in the FMR1 gene is polymorphic, ranging from 5 to 50 repeats in the normal population. Expansion of the repeats to the premutation range (50-200) has been associated with premature ovarian failure (POF). This case-control study was conducted to enumerate CGG repeats in the FMR1 gene in 80 Indian women with non-familial, non-syndromic POF, and 70 controls from the same ethnicity. A possible association between CGG repeats and endocrine profile of these cases was investigated. All patients and controls had CGG repeats in the normal polymorphic range. Serum FSH concentrations were significantly raised in both POF cases and controls having CGG repeats in the 31-40 repeats range (P < 0.0001). POF cases and controls had FSH concentrations of 133.7 versus 84.2 mIU/ml and 16.0 versus 6.2 mIU/ml for >30 repeats versus <30 repeats respectively. Inhibin B concentrations were not associated with CGG repeats. The results of this study indicate that FMR1 premutations are rare in sporadic cases of POF with no family history of fragile X syndrome. However, although in the normal polymorphic range, expansion of the CGG repeat tract to beyond 30 repeats was associated with serum FSH concentrations in both POF cases and controls.

Deciphering the cis-regulatory elements of co-expressed genes in PCOS by in silico analysis.

In recent times, the focus of research in polycystic ovary syndrome (PCOS) has shifted from candidate gene(s) approach to whole genome analysis for deciphering its molecular pathophysiology. In this regard, several microarray studies have been published, showing differential expression of genes between normal and PCOS states. Co-expression of genes as obtained in microarray experiments can also imply co-regulation at the transcriptional level by various transcription factors. In order to identify such transcription factors, the in silico elucidation of Transcription Factor Binding Sites (TFBS) is emerging as an important tool. With this hypothesis, we looked for TFBS over-representation in a PCOS microarray gene set (n=130) using in silico tools. We extracted 1000 bps upstream and 200 bps downstream regions from all these genes and identified 4 different TFBS, which were over-represented as compared to a human promoter background model. These four transcription factors are Staf, E47, CCAAT and CRE-BP1/c-jun. The role of these transcription factors and their compatible members in PCOS pathophysiology is described in details in the text. The factors might provide a novel insight into the pathophysiology of PCOS.

Altered expression of progesterone receptors in testis of infertile men.

Progesterone has been implicated in the process of spermatogenesis. This study aimed to investigate the association of progesterone receptor (PR) expression with spermatogenesis in the testis of infertile men. PR mRNA and protein were assessed by in-situ hybridization and immunohistochemistry in testicular biopsies obtained from 18 infertile men. The extent of spermatogenesis was assessed by Johnsen scoring. None of the patients included in the study had Yq microdeletions. PR expression was almost undetectable in all the testicular sections displaying Sertoli cell only (SCO) or arrest at spermatogonia. Weak cytoplasmic expression was observed in biopsies showing arrest at different stages of meiosis. In biopsies displaying spermatogenesis up to the round spermatid stages, PR expression was observed in both nucleus and cytoplasm of different cell types at intensity lower than that detected in normal biopsies. Normal PR expression was observed in biopsies demonstrating hypospermatogenesis. In biopsies showing mixed phenotypes, the tubules with SCO or spermatogonia arrest showed absence of PR expression; normal PR expression was observed in adjacent tubules showing complete spermatogenesis. Semi-quantitative assessment of PR expression and Johnsen scores in the testicular biopsies of infertile men demonstrating different phenotypes indicated a direct relationship between PR expression and extent of spermatogenesis.

Transfer of isoniazid from circulation to breast milk in lactating women on chronic therapy for tuberculosis.

WHAT IS ALREADY KNOWN ABOUT THIS SUBJECT: Isoniazid is the most widely used first line antituberculosis drug. It is considered safe during lactation, but limited data are available on the transfer of isoniazid from circulation to milk in lactating women, which can provide an assessment of extent of exposure to the nursling. WHAT THIS STUDY ADDS: The study documents the transfer pattern and milk to plasma (M : P) ratio of isoniazid at a steady state. Peak plasma and milk concentrations of isoniazid were reached within 1 h and the projected exposure of the drug to the infant is much lower than the prophylactic dose, supporting its safety during breast feeding. AIM: To determine milk to plasma (M : P) ratios and infant dose (absolute and relative) for isoniazid in lactating women on antituberculosis therapy. METHODS: Concentrations of isoniazid in plasma and milk were measured in exclusively breast feeding women taking 300 mg day(-1) as treatment for tuberculosis. RESULTS: Peak plasma and milk concentrations of isoniazid were observed at 1 h. A mean M : P(AUC) value of 0.89 (95% CI 0.7, 1.1) was calculated for isoniazid from seven women over 24 h. The mean absolute infant dose was estimated to be 89.9 mug kg day(-1) (95% CI 65.6, 114) and the relative infant dose was 1.2% of the weight adjusted maternal dose. CONCLUSIONS: The mean relative dose of isoniazid (1.2%) transmitted to the infant via breast milk is below the 10% notional level of concern. These data suggest that isoniazid therapy is safe during breastfeeding.

Exposure of adult rats to estradiol valerate induces ovarian cyst with early senescence of follicles.

Environmental and therapeutic estrogens are known to play an important role in modulating the reproductive life and pubertal maturation in males as well as in females. Animal studies have shown that exogenously administered estrogen induces follicular cysts. However, the probable mechanisms underlying this abnormal ovarian development and its impact on steroidogenesis have been ill defined. The present study was therefore carried out to understand the ontogeny of ovarian pathology owing to adult estrogenisation. Regularly cycling female Holtzman rats were sacrificed at one week, two weeks, three weeks and four weeks after a subcutaneous administration of 2 mg of estradiol valerate (E(2)V). The effect of this supra-physiological estrogen on serum endocrine profiles, development of follicular cysts, follicular apoptosis and expression of markers of folliculogenesis viz., estrogen receptor (ER)-beta, inhibin A and progesterone receptor (PR) were studied. Results indicate a temporal augmentation of steroidogenesis, which was associated with induction of follicular cyst with theca cell hyperplasia and induction of apoptosis in the primary and secondary follicles of the ovaries. Immuno-histochemical localization showed an increase in inhibin A with a reduction in ER-beta and PR indicating early maturation, poor follicle growth and granulosa cell differentiation. Results indicate that exposure to exogenous estrogen in adulthood can have deleterious effects on the ovarian physiology and endocrinology which may ultimately lead to cystogenesis, loss of follicle pool and early senescence.

Congenital adrenal hyperplasia: biochemical and molecular perspectives.

Congenital adrenal hyperplasia is a disorder occurring in both sexes and is the commonest cause of ambiguous genitalia. It is a group of autosomal recessive disorders in which, on the basis of an enzyme defect the bulk of steroid hormone production by adrenal cortex shifts from corticosteroids to androgens. Autosomal recessive mutations in the CYP21, CYP17, CYP11B1 and 3betaHSD genes that encode steroidogenic enzymes, in addition to mutations in the gene encoding the intracellular cholesterol transport protein steroidogenic acute regulatory protein StAR can cause CAH. Each of the defects causes different biochemical consequences and clinical features. Deficiencies in 21 hydroxylase (21-OH) and 11beta-Hydroxylase (11beta-OH) are the two most frequent causes of CAH. All the biochemical defects impair cortisol secretion, resulting into compensatory hypersecretion of ACTH and consequent hyperplasia of the adrenal cortex. Research in recent years has clarified clinical, biochemical and genetic problems in diagnosis and treatment of the disorders. Expanding knowledge of the gene mutations associated with each of these disorders is providing valuable diagnostic tools in addition to the biochemical profile and phenotype. Genotyping is useful in selecting instances to provide genetic counseling and to clarify ambiguous cases.

Development of an in vitro cell culture model to study milk to plasma ratios of therapeutic drugs.

OBJECTIVE: To create an in vitro cell culture model to predict the M/P (concentration of drug in milk/concentration in maternal plasma) ratios of therapeutic drugs viz. rifampicin, theophylline, paracetamol, and aspirin. MATERIALS AND METHODS: An in vitro cell culture model using CIT3 cells (mouse mammary epithelial cells) was created by culturing the cells on transwells. The cells formed an integral monolayer, allowing only transcellular transport as it happens in vivo. Functionality of the cells was confirmed through scanning electron microscopy. Time wise transfer of the study drugs from plasma to milk was studied and compared with actual (in vivo) M/P ratios obtained at reported tmax for the respective drugs. RESULTS: The developed model mimicked two important intrinsic factors of mammary epithelial cells viz. secretory and tight-junction properties and also the passive route of drug transport. The in vitro M/P ratios at reported tmax were 0.23, 0.61, 0.87, and 0.03 respectively, for rifampicin, theophylline, paracetamol, and salicylic acid as compared to 0.29, 0.65, 0.65, and 0.22, respectively, in vitro. CONCLUSION: Our preliminary effort to develop an in vitro physiological model showed promising results. Transfer rate of the drugs using the developed model compared well with the transfer potential seen in vivo except for salicylic acid, which was transferred in far lower concentration in vitro. The model has a potential to be developed as a non-invasive alternative to the in vitro technique for determining the transfer of therapeutic drugs into breast milk.

Spectrum of MECP2 gene mutations in a cohort of Indian patients with Rett syndrome: report of two novel mutations.

Rett syndrome (RTT) is an X-linked neurodevelopmental disorder, primarily affecting females and characterized by developmental regression, epilepsy, stereotypical hand movements, and motor abnormalities. Its prevalence is about 1 in 10,000 female births. Rett syndrome is caused by mutations within methyl CpG-binding protein 2 (MECP2) gene. Over 270 individual nucleotide changes which cause pathogenic mutations have been reported. However, eight most commonly occurring missense and nonsense mutations account for almost 70% of all patients. We screened 90 individuals with Rett syndrome phenotype. A total of 19 different MECP2 mutations and polymorphisms were identified in 27 patients. Of the 19 mutations, we identified 7 (37%) frameshift, 6 (31%) nonsense, 14 (74%) missense mutations and one duplication (5%). The most frequent pathogenic changes were: missense p.T158M (11%), p.R133C (7.4%), and p.R306C (7.4%) and nonsense p.R168X (11%), p.R255X (7.4%) mutations. We have identified two novel mutations namely p.385-388delPLPP present in atypical patients and p.Glu290AlafsX38 present in a classical patient of Rett syndrome. Sequence homology for p.385-388delPLPP mutation revealed that these 4 amino acids were conserved across mammalian species. This indicated the importance of these 4 amino acids in structure and function of the protein. A novel variant p.T479T has also been identified in a patient with atypical Rett syndrome. A total of 62 (69%) patients remained without molecular genetics diagnosis that necessitates further search for mutations in other genes like CDKL5 and FOXG1 that are known to cause Rett phenotype. The majority of mutations are detected in exon 4 and only one mutation was present in exon 3. Therefore, our study suggests the need for screening exon 4 of MECP2 as first line of diagnosis in these patients.

Genetic variants in the distal enhancer region of the PSA gene and their implication in the occurrence of advanced prostate cancer.

The identification of men predisposed to advanced prostate cancer is important as it influences diagnostic and treatment modalities. In this study, we examined variants in the prostate specific antigen (PSA) gene and their possible association with the risk of prostate cancer, the occurrence of advanced disease, and serum PSA levels. Three functional single nucleotide polymorphisms (SNPs) in the enhancer region of the PSA gene, -5429T/G, -5412T/C and -4643A/G, were genotyped in 84 prostate cancer cases and 109 controls using the SNaPshotTM multiplex technique. Prostate cancer patients were divided into two groups: those with localized (n=37) and advanced (n=36) disease. Between these two groups, two SNPs, -5429T/G and -5412T/C, were found to have statistically significant differences in PSA genotype frequencies. The heterozygous genotype in the PSA gene conferred an increased risk of advanced prostate cancer. After age-adjustment, the estimated OR and 95% CI for -5429T/G and -5412T/C was 3.59 (1.16-11.09; P<0.02), and 3.26 (1.04-10.22; P<0.02), respectively, whereas for -4643A/G, the OR was 2.46 (0.86-7.04; P<0.08). The haplotype -5429G/-5412C/-4643G with 11% frequency conferred a 3.5-fold increased risk of advanced prostate cancer (95% CI = 1.02-11.76; P<0.051). Genotype distribution between the controls and prostate cancer cases did not demonstrate a statistically significant difference (P>0.05). Genotype-based serum PSA levels for each SNP were also observed to be similar (P>0.05). Heterozygosity observed in the PSA gene enhancer region contributes substantially to the occurrence of advanced prostate cancer. The identification of men at risk for advanced disease by PSA genotype may aid in determining the most effective therapeutic strategy, with the aim of improving the quality of life of patients.

CYP11A1 and CYP17 promoter polymorphisms associate with hyperandrogenemia in polycystic ovary syndrome.

OBJECTIVE: To analyze promoter regions of CYP11A1 and CYP17 for putative variations in a defined group of women with polycystic ovary syndrome (PCOS) and to study their association with androgen levels. DESIGN: Retrospective study. SETTING: A secondary referral center for infertility at National Institute for Research in Reproductive Health, Mumbai, India. PATIENT(S): One hundred women whose condition was diagnosed on the basis of the Rotterdam consensus were compared against 100 age-matched controls. INTERVENTION(S): A single sample of blood was collected after overnight fast on day 3 of the menstrual cycle. MAIN OUTCOME MEASURE(S): Plasma levels of T, androstenedione, 17alpha-hydroxyprogesterone, and DHEAS and nucleotide sequence of promoter regions of CYP11A1 and CYP17 genes. RESULT(S): Polymorphisms in promoter regions of the two key androgen-regulating genes, CYP11A1 and CYP17, were found to be significantly associated with T levels in the cohort of well-characterized PCOS cases as compared with controls. The significance was greater in the PCOS cases with both the polymorphisms. CONCLUSION(S): Our study carried out in a defined group of Indian women with PCOS suggests for the first time an individual, as well as combined, association of polymorphisms in CYP11A1 and CYP17 promoters with T levels.

Study of NAT2 gene polymorphisms in an Indian population: association with plasma isoniazid concentration in a cohort of tuberculosis patients.

BACKGROUND AND OBJECTIVES: Polymorphisms of the N-acetyltransferase 2 gene (NAT2) vary remarkably between populations of different ethnic origin. The NAT2 gene determines the individual's acetylator status to metabolize drugs and xenobiotics, influencing their toxicity and efficacy profiles. This study investigates the frequencies of the most commonly studied NAT2 polymorphisms in a southwestern Indian population and compares these with those reported in other Indian and world populations. The association of these polymorphisms with plasma isoniazid concentrations in a cohort of tuberculosis patients has also been investigated. METHODS: NAT2 genotyping of 201 subjects was carried out by PCR-restriction fragment length polymorphism (PCR-RFLP) analysis and DNA sequencing. Acetylation phenotypes were predicted from NAT2 genotypes. The association of NAT2 genotypes with plasma isoniazid concentrations was determined by measuring the plasma levels in tuberculosis patients at different time points using reverse-phase high-performance liquid chromatography (HPLC). RESULTS: The predominant alleles found in this study population were NAT2*5B and NAT2*6A, while NAT2*5B/*6A and NAT2*6A/*6A were the most frequent genotypes; the frequency varied widely from other reported studies in the Indian population. The distribution of slow, intermediate, and fast acetylators was 55%, 32%, and 13%, respectively. We observed relatively higher plasma concentrations of isoniazid in our patients than those reported in other similar studies, and they correlated well with the NAT2 genotypes. CONCLUSION: The results suggested high variation in the frequencies of NAT2 alleles and genotypes within Indian populations, which influence plasma isoniazid concentrations. Further studies of the relationship between NAT2 genotypes and adverse drug events are required to make genotyping a helpful tool for optimizing the isoniazid therapeutic response and minimizing adverse drug reactions, particularly in countries with a high burden of tuberculosis.

Genetic variation in exon 17 of INSR is associated with insulin resistance and hyperandrogenemia among lean Indian women with polycystic ovary syndrome.

OBJECTIVE: Polycystic ovary syndrome (PCOS) is a multigenic disorder, and insulin resistance is one of its hallmark features. Polymorphisms in exon 17 of insulin receptor (INSR) gene are reported to be associated with PCOS. We investigated this association in Indian women and its putative relationship with PCOS associated traits, which has not been explored so far. METHODS: In this case control study, the polymorphisms were investigated by direct sequencing in 180 women with PCOS and 144 age matched controls. Clinical, anthropometric, biochemical, and hormonal parameters were also estimated. RESULTS: The silent C/T polymorphism at His1058 in exon 17 of INSR was found to be present in our study population. The polymorphic genotype (CT+TT) was significantly associated with PCOS in lean women (chi(2)=8.493, df=1, P=0.004). It showed association with higher fasting insulin levels (P=0.02), homeostasis model assessment of insulin resistance (P=0.005), free androgen index (P=0.03), and lower quantitative insulin sensitivity check index (P=0.004) in lean PCOS women. No other novel or known polymorphism was identified in exon 17 in this cohort. CONCLUSIONS: The study shows significant association of C/T polymorphism at His1058 of INSR with PCOS in the lean rather than obese Indian women. Its association with indices of insulin resistance and hyperandrogenemia is also seen in the same group. The findings strengthen the concept that pathogenesis of PCOS is different in lean and obese women.