Newborn screening and single nucleotide variation profiling of TSHR, TPO, TG and DUOX2 candidate genes for congenital hypothyroidism.

High prevalence of congenital hypothyroidism (CH) among Indian newborns prompted us to establish population-specific reference ranges of TSH and to explore the contribution of the common genetic variants in TSHR, TPO, TG and DUOX2 genes towards CH. A total of 1144 newborns (593 males and 551 females) were screened for CH. SNV profiling (n = 22) spanning three candidate genes, i.e. TSHR, TPO and TG was carried out in confirmed CH cases (n = 45). In screen negative cases (n = 700), ten TSHR variants were explored to establish association with CH. No mutation found in DUOX2. The 2.5th to 97.5th percentiles of TSH in these newborns were 0.5 to 12.2 mU/L. In newborns with optimal birth weight, the cut-off was 10 mU/L. Lower or higher birth weight resulted in slightly higher TSH. Two TSHR variants, i.e. rs7144481 and rs17630128 were associated with agenesis, hypoplasia and goiter. The rs2268477 was associated with agenesis and hypoplasia. The rs1991517, rs2075176 and rs2241119 were associated with agenesis only. The rs7144481, rs17630128, rs1991517 and rs2268477 were associated with 2.17, 4.62, 2.91 and 2.29-fold increased risk for CH, respectively. Among the TPO variants, rs867983 and rs2175977 were associated with agenesis and goiter, respectively. Among the TG variants, rs2076740 showed association with agenesis and goiter. Two rare variants i.e. TPO g.IVS14-19 G>C and TG c.1262 C>T were observed in CH cases. No genetic variant identified in the two exons of DUOX2. To conclude, the current study established Indian population-specific normative values for TSH and demonstrates specific genotype-phenotype correlations among three candidate genes.

Role of tagged SNPs of the AGT gene in causing susceptibility to essential hypertension.

AIM: Angiotensinogen (AGT) is one of the candidate genes that has been extensively investigated for association of its variants with essential hypertension. Studies focusing on the contribution of tagged single nucleotide polymorphisms (SNPs) in the AGT gene are limited and lacking from Indian population. Hence, the present study was carried out to examine the role of five tagged SNPs viz., g.6147G>A (rs7539020), g.5978A>G (rs2493134); g.6241T>C (rs1078499), g.7781G>T (rs11122577), and g.5855G>A (rs3789678) in the development of hypertension. MATERIALS AND METHODS: 202 hypertensives and 222 normotensives were screened for five tagged SNPs using the method of polymerase chain reaction restriction fragment length polymorphism (PCR-RFLP). RESULTS: The present study revealed significant association of g.5855G>A polymorphism with essential hypertension in different logistic regression models wherein protection was conferred by g.5855G>A against developing the condition. The polymorphism led to the creation of new exonic splicing enhancer and destruction of exonic splicing silencer site thereby enhancing the process of mRNA splicing. The haplotypes AGTG and GACG were found to have a significant protective effect. Other polymorphisms did not show any significant association with hypertension. CONCLUSION: The present study is the first one to report the protective role of g.5855G>A polymorphism in the development of essential hypertension. The results reflect possibility of ethnic variation in the contribution of g.5855G>A polymorphism of the AGT gene to essential hypertension.

Evaluation of leptin and leptin receptor gene 3' UTR polymorphisms in essential hypertension.

INTRODUCTION: Leptin and leptin receptor gene polymorphisms have been associated with obesity; however, their association with blood pressure has not been fully elucidated. The aim of this study was to examine the effect of tetranucleotide repeat polymorphism in the 3' flanking region of the leptin and leptin receptor gene on blood pressure in hypertensives with obesity. METHODS: Two hundred and eighty hypertensives and 200 healthy controls were analyzed for a tetranucleotide repeat polymorphism of leptin and leptin receptor genes. Genotyping was done by amplifying DNA and determining the allele sizes using gel documentation system. Odds ratios were computed to predict the risk for hypertension caused by specific genotypes of leptin and leptin receptor genes and the effect of interaction between them on the development of hypertension was determined by MDR test. RESULTS: Significant preponderance in the incidence of male sex, obese individuals and those with positive family history was observed with significant elevation in the mean levels of SBP, DBP, BMI and reduction of HDL levels in hypertensives as compared to controls. Class I/I genotypes of leptin showed significantly high risk for developing hypertension irrespective of obesity. Genotypes of leptin receptor did not confer any risk for hypertension and cohorts studied. CONCLUSION: Homozygotes I/I were at greater risk for developing hypertension irrespective of obesity. When leptin and leptin receptor genes were considered together, synergistic interaction was observed between the two genes leading to hypertension, while the polymorphism at leptin gene and obesity was correlated.