Publications by authors named "Giriraj Chandak"

Background: Obesity is among the leading public health threats globally. Over the last few years, visceral adiposity index (VAI), and body adiposity index (BAI), derived from anthropometric, and biochemical measures, have gained importance as a measure of obesity. However, unlike other common indices like body mass index, and waist circumference, the genetic predisposition of VAI, and BAI under-examined.

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Worldwide trends to delay childbearing have increased parental ages at birth. Older parental age may harm offspring health, but mechanisms remain unclear. Alterations in offspring DNA methylation (DNAm) patterns could play a role as aging has been associated with methylation changes in gametes of older individuals.

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  • Type 2 diabetes (T2D) is a complex disease influenced by various genetic factors and molecular mechanisms that vary by cell type and ancestry.
  • In a large study involving over 2.5 million individuals, researchers identified 1,289 significant genetic associations linked to T2D, including 145 new loci not previously reported.
  • The study categorized T2D signals into eight distinct clusters based on their connections to cardiometabolic traits and showed that these genetic profiles are linked to vascular complications, emphasizing the role of obesity-related processes across different ancestry groups.
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Adiposity has gradually become a global public threat over the years with drastic increase in the attributable deaths and disability adjusted life years (DALYs). Given an increased metabolic risk among Asians as compared to Europeans for any given body mass index (BMI) and considering the differences in genetic architecture between them, the present review aims to summarize the findings from genome-wide scans for various adiposity indices and related anthropometric measures from Asian populations. The search for related studies, published till February 2022, were made on PubMed and GWAS Catalog using search strategy built with relevant keywords joined by Boolean operators.

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Background: Maternal vitamin B12 deficiency plays a vital role in fetal programming, as corroborated by previous studies on murine models and longitudinal human cohorts.

Objectives: This study assessed the effects of diet-induced maternal vitamin B12 deficiency on F1 offspring in terms of cardiometabolic health and normalization of these effects by maternal-periconceptional vitamin B12 supplementation.

Methods: A diet-induced maternal vitamin B12 deficient Wistar rat model was generated in which female rats were either fed a control AIN-76A diet (with 0.

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  • Human height is primarily determined by genetics, but this study explores how modifiable epigenetic factors, specifically blood DNA methylation, influence child height in low and middle-income countries (LMIC).
  • The research identifies a significant link between DNA methylation in the SOCS3 gene and child height, with findings replicating in a high-income country cohort, showing that this effect is independent of genetic factors.
  • Analysis reveals that SOCS3 methylation explains up to 9.5% of height variance in mid-childhood and is influenced by prenatal maternal folate and socio-economic status, highlighting the potential role of epigenetic modifications in child growth in LMIC.
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Type 2 diabetes (T2D) is a heterogeneous disease that develops through diverse pathophysiological processes. To characterise the genetic contribution to these processes across ancestry groups, we aggregate genome-wide association study (GWAS) data from 2,535,601 individuals (39.7% non-European ancestry), including 428,452 T2D cases.

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Preeclampsia is a placental vascular pathology and hypoxia is known to influence placental angiogenesis. Hypoxia Inducible Factors (HIF1α and HIF3α) mediate the response to cellular oxygen concentration and bind to hypoxia response element of target genes. However the mechanism regulating above activity is not well-understood.

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In The Pune Maternal Nutrition Study, vitamin B12 deficiency was seen in 65% of pregnant women, folate deficiency was rare. Maternal total homocysteine concentrations were inversely associated with offspring birthweight, and low vitamin B12 and high folate concentrations predicted higher offspring adiposity and insulin resistance. These findings guided a nested pre-conceptional randomised controlled trial 'Pune Rural Intervention in Young Adolescents'.

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Background: Leber hereditary optic neuropathy (LHON) is a maternally inherited disease resulting in irreversible visual loss usually in patients belonging to the age group of 15-35 years. Clinically, the patients present with sequential or bilateral, painless, progressive visual loss with central (or ceco-central) scotomas. Although the three mutations, namely, G11778A, T14484C, and G3460A contribute to >95% of LHON cases globally, the relative frequency of each mutation varies.

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Background: Genetic variants within nearly 1000 loci are known to contribute to modulation of blood lipid levels. However, the biological pathways underlying these associations are frequently unknown, limiting understanding of these findings and hindering downstream translational efforts such as drug target discovery.

Results: To expand our understanding of the underlying biological pathways and mechanisms controlling blood lipid levels, we leverage a large multi-ancestry meta-analysis (N = 1,654,960) of blood lipids to prioritize putative causal genes for 2286 lipid associations using six gene prediction approaches.

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Article Synopsis
  • Variants in the PRSS1 and PRSS2 genes are linked to chronic pancreatitis (CP), prompting research into whether a deletion variant affecting two trypsinogen pseudogenes (PRSS3P2 and TRY7) might influence CP risk.
  • A study analyzed this deletion in over 4,000 participants from different countries and found that it is associated with a protective effect against CP, especially in French, German, and Japanese populations.
  • The research suggests that the deletion enhances the function of remaining genes, leading to regulated PRSS2 expression, which could be crucial in understanding CP susceptibility.
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Sickle cell disease (SCD) is a disease of abnormal hemoglobin associated with severe clinical phenotype and recurrent complications. Hydroxyurea (HU) is one of the US-FDA approved and commonly used drug for the treatment of adult SCD patients with clinical -severity. However, its use in the pediatric groups remains atypical.

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  • Common SNPs may account for 40-50% of human height variation, and this study identifies 12,111 SNPs linked to height from a large sample of 5.4 million individuals.
  • These SNPs cluster in 7,209 genomic segments, encompassing about 21% of the genome and showing varying densities enriched in relevant genes.
  • While these SNPs explain a substantial portion of height variance in European populations (40-45%), their predictive power is lower (10-24%) in other ancestries, suggesting a need for more research to enhance understanding in diverse populations.
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  • Researchers studied the genetic connections to blood fats using data from 1.6 million people from different backgrounds to understand why certain fats are higher or lower in the body.
  • They looked at special genes and how they interact in the liver and fat cells, finding that the liver plays a big part in controlling fat levels.
  • Two specific genes, CREBRF and RRBP1, were highlighted as important in understanding how our bodies manage fats due to strong supporting evidence.
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Introduction: Biosynthesis of long-chain polyunsaturated fatty acids requires sequential activities of desaturases and elongases for conversion of fatty acid precursors to products. The delta-6 desaturase enzyme, encoded by FADS2 gene, is a rate limiting enzyme in this pathway. Alterations in D6D enzyme activity can lead to altered fatty acid profiles.

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Changes in brain morphology have been reported during development, ageing and in relation to different pathologies. Brain morphology described by the shape complexity of gyri and sulci can be captured and quantified using fractal dimension (FD). This measure of brain structural complexity, as well as brain volume, are associated with intelligence, but less is known about the sexual dimorphism of these relationships.

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  • The study examined DNA methylation across 30 datasets with 3474 individuals from various tissues and ethnicities, identifying 4143 highly variable methylation sites (hvCpGs).
  • These hvCpGs were influenced by genetic factors but were not solely determined by them, nor were they significantly affected by factors like age, sex, or cell differences.
  • The hvCpGs showed patterns linking to retrovirus elements and were associated with early environmental factors, making them important for studying how early DNA methylation may affect long-term health.
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We assembled an ancestrally diverse collection of genome-wide association studies (GWAS) of type 2 diabetes (T2D) in 180,834 affected individuals and 1,159,055 controls (48.9% non-European descent) through the Diabetes Meta-Analysis of Trans-Ethnic association studies (DIAMANTE) Consortium. Multi-ancestry GWAS meta-analysis identified 237 loci attaining stringent genome-wide significance (P < 5 × 10), which were delineated to 338 distinct association signals.

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South Asians are at high risk of developing type 2 diabetes (T2D). We carried out a genome-wide association meta-analysis with South Asian T2D cases (n = 16,677) and controls (n = 33,856), followed by combined analyses with Europeans (n = 231,420). We identify 21 novel genetic loci for significant association with T2D (P = 4.

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Size at birth is known to be influenced by various fetal and maternal factors, including genetic effects. South Asians have a high burden of low birth weight and cardiometabolic diseases, yet studies of common genetic variations underpinning these phenotypes are lacking. We generated independent, weighted fetal genetic scores (fGSs) and maternal genetic scores (mGSs) from 196 birth weight-associated variants identified in Europeans and conducted an association analysis with various fetal birth parameters and anthropometric and cardiometabolic traits measured at different follow-up stages (5-6-year intervals) from seven Indian and Bangladeshi cohorts of South Asian ancestry.

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Background: The prevalence of cardiometabolic disease (CMD) is rising globally, with environmentally induced epigenetic changes suggested to play a role. Few studies have investigated epigenetic associations with CMD risk factors in children from low- and middle-income countries. We sought to identify associations between DNA methylation (DNAm) and CMD risk factors in children from India and The Gambia.

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