Complex genetic origin of Indian populations and its implications

Congenital Hyperinsulinism India Association: An Approach to Address the Challenges and Opportunities of a Rare Disease

India's population complexity presents varied challenges in genetic research, and while facilities have gained traction in tier-1 and -2 cities, reliance on international collaborations often delays such investigations. COVID-19 further exacerbated the issues with such sample sharing. Congenital Hyperinsulinism (CHI) is a rare genetic disorder of pancreatic β-cells causing hypoglycaemia in children due to abnormal insulin secretion. Given India's high birth rate and consanguineous populations, annual CHI cases are estimated to be around up to 10,000, with up to 50% having unexplained genetic causes. Diffuse or atypical lesions in such patients often necessitate near-total-pancreatectomy, risking pancreatic exocrine insufficiency and diabetes, requiring lifelong therapy. Also, novel genetic variations complicate accurate diagnosis, risk assessment, and counselling, emphasising the need for rapid genetic assessment to prevent neurological injuries and inform treatment decisions. Despite significant efforts at many institutes, there are no dedicated organisations for CHI in India. With the implementation of the National Policy for Rare Diseases 2021, we plan to form a non-profit organisation, "Congenital Hyperinsulinism India Association (CHIA)", comprising paediatric endocrinologists, paediatricians, geneticists, and independent researchers. The aims of this association are to generate a national database registry of patients, formulate a parent support group and CHIA consortium, design patient information leaflets, as well as foster genomic collaborations and promote clinical trials. Such steps will help sensitise the health authorities and policy makers, urging them to improve the allocation of health budgets for rare diseases, as well as empower patients and their families, contributing towards a better quality of life.

Frequency Distributions of Alleles and Genotypes and Lung Cancer Risk of Polymorphisms DCK, SLC29A1, and SLC29A3 in South Indian Healthy Population

Introduction Gemcitabine, a cytotoxic drug, is used to treat a variety of solid tumors, such as pancreatic, lung, and breast malignancies. The efficiency rates for gemcitabine have decreased due to an increase in genetic instability. The association between gene polymorphisms and the efficacy of gemcitabine therapy may be better known by understanding the intricacies of genetics that target a few or more genes in drug-targeting metabolic pathways. Moreover, several studies have documented differences in the therapeutic response among various ethnicities to gemcitabine chemotherapy. Therefore, the purpose of this study was to determine the normative frequencies of gene polymorphisms linked to the metabolic pathway of gemcitabine (DCK -360C>G (80143932), SLC29A1 -201A>G (760370), SLC29A1 +913C>T (9394992), SLC29A3 +4967C>A (10999776)) in Southern part of Indian healthy population and compared it with the 1000 genome population. In addition, the association of the above single nucleotide polymorphisms (SNPs) with lung cancer susceptibility was also evaluated. Methods The present study used real-time polymerase chain reaction (RT-PCR) for performing genotyping in 184 healthy participants as well as 123 South Indian patients with lung cancer. The frequencies of alleles and genotypes of the aforementioned genetic variants were in Hardy-Weinberg equilibrium (p > 0.05). Results The minor allele frequencies (MAF) of the SNPs DCK -360C>G (80143932), SLC29A1 -201A>G (760370), SLC29A1+913C>T (9394992), SLC29A3 +4967C>A (10999776) were 3.8%, 17.7%, 27.7%, 29.3% respectively in healthy population. The MAF of the SNPs, DCK -360C>G (80143932), SLC29A1 -201A>G (760370), SLC29A1 +913C>T (9394992), SLC29A3 +4967C>A (10999776) in lung cancer patients was 2%, 15%, 23.2%, and 24.4% respectively. A trend toward a protective effect against lung cancer was observed with SLC29A1 +913C>T (9394992). Conclusion The observed frequencies of alleles and genotypes in the South Indian population were significantly different as compared to the 1000 genome population. In the present study, an association of SLC29A1 rs9394992 C>T between lung cancer patients and healthy subjects showed a trend toward protective effect against lung cancer risk. There was no association found between the other studied SNPs and lung cancer risk.

From teeth to ethnicity: A neural network approach to predicting population of origin through dental traits and anomalies

Background

This study aimed to investigate the prevalence of dental traits and anomalies in five North Indian populations (Khas Bodhi, Jaat, Khatri, Garhwali, and Gujjar) and predict the population of origin based on these traits and anomalies for forensic applications.

Methods

We assessed dental traits and anomalies in 454 individuals through intraoral examination. Neural network analysis was employed to predict the population of origin based on a combination of dental traits and anomalies.

Results

Shovel-shaped incisors exhibited the highest prevalence among the studied traits and anomalies, occurring in 65.4% of the sample. Moreover, shovel-shaped incisors were found to be the most important predictor of population. Neural network analysis indicated that the most accurate population prediction among the studied populations was for the Garhwali origin, achieving a recall rate of 78.3%. While this may appear relatively low, it is crucial to emphasise that the proposed method serves as a corroborative tool for various forensic investigations.

Conclusion

This study suggests that dental traits and anomalies can be valuable in predicting the population of origin within Indian populations for forensic purposes. The work enhances the forensic identification process by providing an additional layer of evidence for consideration in identifying both individuals and their ethnic backgrounds. Further research is necessary to enhance the robustness of prediction models.

The genetic admixture and assimilation of Ahom: a historic migrant from Thailand to India

The Northeastern region of India is considered a gateway for modern humans' dispersal throughout Asia. This region is a mixture of various ethnic and indigenous populations amalgamating multiple ancestries. One reason for such amalgamation is that, South Asia experienced multiple historic migrations from various parts of the world. A few examples explored genetically are Jews, Parsis and Siddis. Ahom is a dynasty that historically migrated to India during the 12th century. However, this putative migration has not been studied genetically at high resolution. Therefore, to validate this historical evidence, we genotyped autosomal data of the Modern Ahom population residing in seven sister states of India. Principal Component and Admixture analyses haave suggested a substantial admixture of the Ahom population with the local Tibeto-Burman populations. Moreover, the haplotype-based analysis has linked these Ahom individuals mainly with the Kusunda (a language isolated from Nepal) and Khasi (an Austroasiatic population of Meghalaya). Such unexpected presence of widespread population affinities suggests that Ahom mixed and assimilated a wide variety of Trans-Himalayan populations inhabiting this region after the migration. In summary, we observed a significant deviation of Ahom from their ancestral homeland (Thailand) and extensive admixture and assimilation with the local South Asian populations.

South Asia: The Missing Diverse in Diversity

South Asia, making up around 25% of the world's population, encompasses a wide range of individuals with tremendous genetic and environmental diversity. This region, which spans eight countries, is home to over 4500 anthropologically defined groups that speak numerous languages and have an array of religious beliefs and cultures, making it one of the most diverse places in the world. Much of the region's rich genetic diversity and structure is the result of a complex combination of population history, migration patterns, and endogamous practices. Despite the overwhelming size and diversity, South Asians have often been underrepresented in genetic research, making up less than 2% of the participants in genetic studies. This has led to a lack of population specific understanding of genetic disease risks. We aim to raise awareness about underlying genetic diversity in this ancestry group, call attention to the lack of representation of the group, and to highlight strategies for future studies in South Asians.

Recent Advances in Inherited Cardiac Arrhythmias and Their Genetic Testing

Inherited arrhythmias, encompassing conditions such as cardiomyopathies, cardiac ion channel disorders, and coronary heart disease, represent the common causes that elevate the threat of sudden cardiac death among adults. Researchers have pinpointed the genes responsible for these hereditary arrhythmias in the last 30 years. Concurrently, it has become clear that the genetic makeup underlying these conditions is more intricate than previously understood. Evolution in DNA sequencing techniques, particularly next-generation sequencing, has empowered us to learn these intricate hereditary characteristics. Genetic testing is crucial in diagnosing, assessing risk, and determining treatment for individuals with these conditions and their family members. The need for collaborative endeavors to comprehend and address these uncommon yet potentially life-threatening disorders is becoming more evident. This review aims to inform readers of the latest advances in understanding hereditary arrhythmias and provide the groundwork for collaborative genetic testing initiatives to characterize these disorders in the general population.

Advancements and Challenges in Ancient DNA Research: Bridging the Global North-South Divide

Ancient DNA (aDNA) research first began in 1984 and ever since has greatly expanded our understanding of evolution and migration. Today, aDNA analysis is used to solve various puzzles about the origin of mankind, migration patterns, and the spread of infectious diseases. The incredible findings ranging from identifying the new branches within the human family to studying the genomes of extinct flora and fauna have caught the world by surprise in recent times. However, a closer look at these published results points out a clear Global North and Global South divide. Therefore, through this research, we aim to emphasize encouraging better collaborative opportunities and technology transfer to support researchers in the Global South. Further, the present research also focuses on expanding the scope of the ongoing conversation in the field of aDNA by reporting relevant literature published around the world and discussing the advancements and challenges in the field.

Clinico-epidemiology and aetiopathogenesis of gallstone disease in the South Asian region: a scoping review protocol

INTRODUCTION

Pathogenesis of gallstones (GS) is multifactorial and is influenced by numerous environmental and genetic risk factors. As a result, clinico-epidemiology and aetiopathogenesis of GS vary in different populations. Understanding the aetiopathogenesis of GS for different populations is imperative in control and prevention of GS disease and its associated complications. This protocol describes the methodology of a scoping review which focuses on synthesising the most updated knowledge on GS disease in South Asia.

METHODS AND ANALYSIS

The scoping review proposed in this protocol will be guided by Arksey and O'Malley's framework and the Joanna Briggs Institute Reviewers' Manual. Accordingly, population, concept and context strategy will be used to formulate the scoping review question, eligibility criteria and search strategy. In the search, electronic databases, MEDLINE/PubMed, ScienceDirect, Scopus, Cochrane library, CINAHL, Trip, and Google scholar, as well as various grey literature sources will be used in synthesising and presenting the findings on clinico-epidemiology and aetiopathogenesis of GS disease in South Asia.

ETHICS AND DISSEMINATION

As secondary data will be used in the study, ethical approval will not be required. The scoping review proposed by this protocol will accurately summarise the current knowledge on GS disease in South Asia based on published and unpublished literature on the field. Thus, the evidence presented in the review will be important for healthcare providers to make decisions on the control and prevention of GS disease and as well as to identify future research priorities on GS disease in South Asia.

Rare disease patients in India are rarely involved in international orphan drug trials

We wished to determine whether rare diseases patients from India had been enrolled in international trials to develop novel orphan drugs. There are two reasons to be interested in this. (a) Different ethnic or racial groups may respond differently to a particular drug. India has huge ethnic diversity, and to exclude such participants is to severely limit the diversity of any trial; (b) Even if a suitable drug for a rare disease is available in India, it may be astronomically priced, in a country where most healthcare expenditure is out-of-pocket. We identified 63 orphan drugs, approved by the US Food and Drug Administration (FDA) after 2008, for which there were 202 trials in the US government's clinical trial registry, ClinicalTrials.gov. Only nine of these trials had run in India. These trials pertained to six drugs. The drugs were for the conditions B-cell Lymphoma, Chronic Myeloid Leukemia, Gaucher disease Type 1, Malaria, Myeloma and Pulmonary Arterial Hypertension. Further research is required as to why patients from India are not part of foreign drug development programmes for rare diseases. We then asked how many of the remaining 193 trials had recruited people of Indian origin, residing in other countries, and found that not more than 1% of these trials had done so. Also, only 11 of the 193 trials had recruited from other lower income countries. Participation from low-income countries in trials for orphan drugs is poor.

Pediatric inflammatory bowel disease: Is it really uncommon in Asian children?

Background/Aim

Inflammatory bowel disease (IBD) is said to be rare in Asian children, and there is scarce information from India. We therefore analyzed our experience of pediatric IBD.

Methods

Prospectively maintained data of 105 consecutive children [median age 12 (IQR:7–14) years, 71 males] with IBD from July 2001 through June 2016 were retrospectively analyzed. Their detailed clinical features, endoscopic appearance, histopathology, and treatment outcomes were recorded. For Crohn's disease (CD), disease phenotype and disease location were assessed as per Paris classification.

Results

Disease spectrum includes ulcerative colitis (UC), 55 (52%); CD, 43 (41%); and IBD‐unclassified, 7 (7%). There was a significant increase in the number of cases in the last 5 years compared to the previous 10 years (63 vs. 42, r² = 0.96). Most UC cases (75%) had extensive/pancolitis, 74% of CD had colonic/ileocolonic disease, and 65% had inflammatory phenotype. Fever, growth failure, pain in abdomen, and need for surgery were significantly more frequent in CD than in UC (P < 0.0001). Over a median follow up of 19 (IQR: 7–48) months, remission was achieved in 48 of 51 (94%) UC patients and in 24 of 34 (70.6%) CD patients; an immunomodulator was required to maintain remission in 67% of UC cases. In CD, there was a significant reduction in the use of empirical antitubercular therapy (76%, P = 0.008) with time, and disease progressed in three.

Conclusions

IBD is not uncommon, and the incidence seems to be increasing among Indian children. UC is more common than CD and is more often an extensive disease. CD is mainly an inflammatory phenotype. The majority of children with IBD required an immunomodulator to maintain remission.

The role of patient organizations in the rare disease ecosystem in India: an interview based study

Background

Rare diseases (RDs) affect a small percentage of the population but can be severely debilitating and life-threatening. Historically, patient groups (PGs) have been the prime movers in raising awareness about these diseases and advocating for national supportive policies. They have also driven relevant research programs. In India too, PGs have made significant contributions to the national RD ecosystem.

Objective

To assess the contribution of various Indian RD PGs, we carried out an interview-based study of 19organizations. This study aims to highlight the origins and achievements of these groups and the challenges that they have faced. The study also helps to capture the changes in the RD ecosystem that have taken place in recent years.

Result

Of the 19 PGs, two are umbrella organizations, two are other organizations of national scope and 15 are disease specific groups. 14 interviewees were affected by an RD either directly or through a family member. Lack of awareness about RDs in the medical community was the biggest challenge, leading to a delay in diagnosis and subsequent management. Only two out of the 15 conditions have a definitive treatment. However, many of the diseases can be managed with replacement therapies administered for the patient’s entire life, or other supportive therapies. Most diagnostics and treatment regimens that are available globally are now available in India but are expensive and usually available only in a few major cities. These problems are compounded by a lack of medical insurance schemes and government policies to support these patients. The biggest achievement of the PGs was the passing of National Policy for Treatment of Rare Diseases in 2017, unfortunately since put in abeyance. If reinstated, and properly implemented, this policy could significantly improve RD management in the country.

Conclusion

PGs have had a significant role in bringing diagnostics and treatments to India. They have also raised awareness about RDs and related issues such as newborn screening, prenatal diagnostics and genetic counselling. This study highlighted the recommendations of various PGs. The government should address these recommendations and institutionalize the participation of the PGs in formal decision making.

Electronic supplementary material

The online version of this article (10.1186/s13023-019-1093-6) contains supplementary material, which is available to authorized users.

Autoantibodies in acquired myasthenia gravis: Clinical phenotype and immunological correlation

BACKGROUND

Data on antibody profile in myasthenia gravis (MG) from India are limited.

OBJECTIVES

To investigate antibody profile in patients with MG and their clinical correlates.

PATIENTS AND METHODS

Patients of MG (n = 85, M:F::1.1:1, mean age: 39.29 ± 17.3 years, mean symptom duration: 72.94 ± 91.8 months) were evaluated for clinical features, MG foundation of America (MGFA) score, response to treatment, and outcome at last follow-up. Antibodies to acetylcholine receptor (AChR), muscle-specific kinase (MUSK), titin and ryanodine receptor (RYR) were analysed using ELISA.

RESULTS

Based on the regional distribution of weakness, the cohort could be categorized as: generalized: 60, ocular: 16 and oculo-bulbar: 9. Sixty patients were followed up for a mean duration of 26.74 ± 13.8 months. Outcome at last follow-up was as follows: remission-22, no remission-33 and dead-5. AChR and MUSK antibodies were detected in 58 and 8 patients, respectively. Frequency of generalized MG, worse MGFA score during the disease course and thymomatous histology significantly correlated with presence of AChR-antibodies, though outcome at last follow-up was comparable between AChR-antibody positive and negative groups. Patients with MUSK antibodies had oculo-bulbar or generalized MG and frequent respiratory crisis, but majority improved or remitted with treatment. Titin antibodies were detected in 31.8% and RYR antibodies in 32.9%. Their presence did not correlate with age at onset of MG, severity or presence of thymoma.

CONCLUSION

This report highlights the spectrum of antibodies in MG in an Indian cohort. AChR-antibody positivity correlated with clinical severity. Outcome was good in majority of MUSK antibody-positive MG. The role of other antibodies, complementary vs epiphenomenon, remains open.

Harnessing genomics to improve outcomes for women with cancer in India: key priorities for research

Cumulatively, breast, cervical, ovarian, and uterine cancer account for more than 70% of cancers in women in India. Distinct differences in the clinical presentation of women with cancer suggest underlying differences in cancer biology and genetics. The peak age of onset of breast and ovarian cancer appears to be a decade earlier in India (age 45-50 years) than in high-income countries (age >60 years). Understanding these differences through research to develop diagnosis, screening, prevention, and treatment frameworks that ar e specific to the Indian population are critical and essential to improving women's health in India. Since the sequencing of the human genome in 2001, applications of advanced technologies, such as massively parallel sequencing, have transformed the understanding of the genetic and environmental drivers of cancer. How can advanced technologies be harnessed to provide health-care solutions at a scale and to a budget suitable for a country of 1·2 billion people? What research programmes are necessary to answer questions specific to India, and to build capacity for innovative solutions using these technologies? In order to answer these questions, we convened a workshop with key stakeholders to address these issues. In this Series paper, we highlight challenges in tackling the growing cancer burden in India, discuss ongoing genomics research and developments in infrastructure, and suggest key priorities for future research in cancer in India.

Spectrum of genomic variations in Indian patients with progressive familial intrahepatic cholestasis

BACKGROUND

Progressive familial intrahepatic cholestasis (PFIC) is caused by variations in ATP8B1, ABCB11 or ABCB4 genes. Data on genetic variations in Indian patients with PFIC are lacking.

METHODS

Coding and splice regions of the three genes were sequenced in unrelated Indian children with PFIC phenotype. The variations identified were looked for in parents, 30 healthy persons and several variation databases, and their effect was assessed in-silico.

RESULTS

Among 25 children (aged 1-144 months), nine (36%) had unique major genomic variations (ATP8B1: 4, ABCB11: 3 and ABCB4: 2). Seven had homozygous variations, which were assessed as 'pathogenic' or 'likely pathogenic'. These included: (i) four amino acid substitutions (ATP8B1: c.1660G > A/p.Asp554Asn and c.2941G > A/p.Glu981Lys; ABCB11: c.548 T > C/p.Met183Thr; ABCB4: c.431G > A/p.Arg144Gln); (ii) one 3-nucleotide deletion causing an amino acid deletion (ATP8B1: c.1587_1589delCTT/p.Phe529del); (iii) one single-nucleotide deletion leading to frame-shift and premature termination (ABCB11: c.1360delG/p.Val454Ter); and (iv) a complex inversion of 4 nucleotides with a single-nucleotide insertion leading to frame-shift and premature termination (ATP8B1: c.[589_592inv;592_593insA]/p.Gly197LeufsTer10). Two variations were found in heterozygous form: (i) a splice-site variation likely to cause abnormal splicing (ABCB11: c.784 + 1G > C), and (ii) a nucleotide substitution that created a premature stop codon (ABCB4: c.475C > T/p.Arg159Ter); these were considered as variations of uncertain significance. Three of the nine variations were novel.

CONCLUSIONS

Nine major genomic variations, including three novel ones, were identified in nearly one-third  of Indian children with PFIC. No variation was identified in nearly two-thirds of patients, who may have been related to variations in promoter or intronic regions of the three PFIC genes, or in other bile-salt transport genes.

Interethnic Differences in Single and Haplotype Structures of Folylpolyglutamate Synthase and Gamma-glutamyl Hydrolase Variants and Their Influence on Disease Susceptibility to Acute Lymphoblastic Leukemia in the Indian Population: An Exploratory Study

Aim: We aim to establish the genotype and haplotype frequencies of folylpolyglutamate synthase (FPGS rs10106 and rs1544105) and gamma-glutamyl hydrolase (GGH rs3758149 and rs11545078) variants in the South Indian population (SI) and to study the association of these variants with susceptibility to acute lymphoblastic leukemia (ALL). We also aim to compare the genotype and haplotype frequencies of studied variants with those of superpopulations from the 1000 Genomes Project collected in phase-3 and other published studies in the literature. Materials and Methods: A total of 220 unrelated healthy volunteers and 151 patients with ALL of both sexes were recruited for the study. Extracted DNA was subjected to genotyping by allelic discrimination using quantitative real-time-polymerase chain reaction. Genotype details of the studied variants in other ethnicities were obtained from 1000 genomes project Phase 3 data. Haploview software was used to construct haplotypes. Results:: In our study, the frequencies of FPGS rs1006'G' and rs1544105'A' alleles were found to be 37% and 37.2%, respectively, and the frequencies of GGH rs3758149'T' and GGH rs11545078'T' alleles were found to be 29.8% and 16.7%, respectively. Among the studied variants, FPGS rs1544105'AA' genotype carriers were found to be susceptible to the risk of ALL (odds ratio: 2.16; 95% confidence interval [CI]: 1.15–4.07; P = 0.02). Haplotype structures of FPGS and GGH variants in SI population were significantly different from other ethnicities (P < 0.05), except the South Asian superpopulation. Conclusion: FPGS rs1544105'AA' genotype was found to influence the risk for ALL. Intra and interethnic differences exist in the distribution of studied variants. Therefore, the impact of each variant on the susceptibility and outcome of diseases may differ between populations.

Genetic polymorphisms in cyclin H gene are associated with oxaliplatin-induced acute peripheral neuropathy in South Indian digestive tract cancer patients

PURPOSE

Digestive tract cancer patients treated with oxaliplatin are often associated with the development of peripheral neuropathy. The aim of the present study is to identify the influence of single-nucleotide polymorphisms (SNPs) in genes involved in oxaliplatin metabolism, cell cycle control, detoxification or excretion pathways with the development of oxaliplatin-induced acute peripheral neuropathy (acute OXAIPN) and its severity among digestive tract cancer patients treated with oxaliplatin-based chemotherapy.

PATIENTS AND METHODS

A total of 228 digestive tract cancer patients undergoing with the oxaliplatin-based chemotherapy between November 2014 and December 2016 were included in the current study. Genomic DNA was extracted from peripheral blood by standard phenol-chloroform method. Genotyping of five SNPs in four genes [GSTP₁ (rs1965), ABCG2 (rs3114018), CCNH (rs2230641, rs3093816), AGXT (rs4426527)] was carried out by Real-Time TaqMan SNP genotyping assay.

RESULTS

We found that the two genetic variants rs2230641 and rs3093816 in cyclin H (CCNH) gene were significantly associated with both the incidence and severity of acute OXAIPN. For CCNH-rs2230641 (AA vs AG+GG; dominant model) Incidence: OR 2.62, 95% CI 1.44-4.75, p = 0.001, severity; OR 4.64, 95% CI 1.58-13.62, p = 0.002. For CCNH-rs3093816 (AA vs AG+GG; dominant model); incidence: OR 3.43, 95% CI 1.57-7.50, p = 0.001; severity: OR 2.36, 95% CI 1.05-5.30, p = 0.033.

CONCLUSIONS

The results of the present study found significant association between CCNH polymorphisms and acute OXAIPN development. However, further studies are warranted from independent groups to validate our study results.

Genetic variations in the Dravidian population of South West coast of India: Implications in designing case-control studies

Background & objectives:

Indian data have been largely missing from genome-wide databases that provide information on genetic variations in different populations. This hinders association studies for complex disorders in India. This study was aimed to determine whether the complex genetic structure and endogamy among Indians could potentially influence the design of case-control studies for autoimmune disorders in the south Indian population.

Methods:

A total of 12 single nucleotide variations (SNVs) related to genes associated with autoimmune disorders were genotyped in 370 healthy individuals belonging to six different caste groups in southern India. Allele frequencies were estimated; genetic divergence and phylogenetic relationship within the various caste groups and other HapMap populations were ascertained.

Results:

Allele frequencies for all genotyped SNVs did not vary significantly among the different groups studied. Wright's F_ST was 0.001 per cent among study population and 0.38 per cent when compared with Gujarati in Houston (GIH) population on HapMap data. The analysis of molecular variance results showed a 97 per cent variation attributable to differences within the study population and <1 per cent variation due to differences between castes. Phylogenetic analysis showed a separation of Dravidian population from other HapMap populations and particularly from GIH population.

Interpretation & conclusions:

Despite the complex genetic origins of the Indian population, our study indicated a low level of genetic differentiation among Dravidian language-speaking people of south India. Case-control studies of association among Dravidians of south India may not require stratification based on language and caste.

Unraveling the Population History of Indian Siddis

The Siddis are a unique Indian tribe of African, South Asian, and European ancestry. While previous investigations have traced their ancestral origins to the Bantu populations from subSaharan Africa, the geographic localization of their ancestry has remained elusive. Here, we performed biogeographical analysis to delineate the ancestral origin of the Siddis employing an admixture based algorithm, Geographical Population Structure (GPS). We evaluated the Siddi genomes in reference to five African populations from the 1000 Genomes project, two Bantu groups from the Human Genome Diversity Panel (HGDP) and five South Indian populations. The Geographic Population Structure analysis localized the ancestral Siddis to Botsawana and its present-day northeastern border with Zimbabwe, overlapping with one of the principal areas of secondary Bantu settlement in southeast Africa. Our results further indicated that while the Siddi genomes are significantly diverged from that of the Bantus, they manifested the highest genomic proximity to the North-East Bantus and the Luhyas from Kenya. Our findings resonate with evidences supporting secondary Bantu dispersal routes that progressed southward from the east African Bantu center, in the interlacustrine region and likely brought the ancestral Siddis to settlement sites in south and southeastern Africa from where they were disseminated to India, by the Portuguese. We evaluated our results in the light of existing historical, linguistic and genetic evidences, to glean an improved resolution into the reconstruction of the distinctive population history of the Siddis, and advance our knowledge of the demographic factors that likely contributed to the contemporary Siddi genomes.

Environmental selection influences the diversity of TLR genes in ethnic Rajbanshi population of North Bengal Region of India

Background

Toll-like receptors are the mediators of the innate immune response to pathogens. In human, this gene family regulates the inflammatory pathways and is associated with the susceptibility to infection.

Subjects and methods

The distribution and the diversity patterns of TLR genes in Rajbanshi population (n = 85) who are the inhabitants of the Northern part of West Bengal, have been investigated in the present study. PCR-SSP was done for all the ten TLR genes. We have also constructed the phylogenetic tree principal component analysis and genetic distance for all the four populations.

Results

It has been observed that in Rajbanshi population, the frequency of TLR8 (0.894) is higher and the frequency of TLR2 (0.176) is very low. Dendrogram based analysis, as well as the PCA plot, documented the closeness of Rajbanshi and Gurkha population. However, Rabha is distantly related to Rajbanshi population though evidences suggest their emergence from the same East-Asian lineage. Genetic distances between Rajbanshi–Gurkha and Rajbanshi–Muslim are very much smaller than that of Rajbanshi–Rabha populations.

Interpretations & conclusions

Therefore, it may be concluded that Rajbanshi, Gurkha and Muslims are very much mixed populations and have genetic closeness due to exposure to similar environmental conditions. On the other hand, the Rabhas strictly follow the endogamy and are restricted to a particular region and therefore maintain considerable distances with the other three populations. The data showed some interesting observations which deviate the contemporary thought in respect to the population genetics.

Inflammatory bowel disease in India - Past, present and future

There is rising incidence and prevalence of inflammatory bowel disease (IBD) in India topping the Southeast Asian (SEA) countries. The common genes implicated in disease pathogenesis in the West are not causal in Indian patients and the role of "hygiene hypothesis" is unclear. There appears to be a North-South divide with more ulcerative colitis (UC) in north and Crohn's disease (CD) in south India. IBD in second generation Indian migrants to the West takes the early onset and more severe form of the West whereas it retains the nature of its country of origin in migrants to SEA countries. The clinical presentation is much like other SEA countries (similar age and sex profile, low positive family history and effect of smoking, roughly similar disease location, use of aminosalicylates for CD, low use of biologics and similar surgical rates) with some differences (higher incidence of inflammatory CD, lower perianal disease, higher use of aminosalicylates and azathioprine and lower current use of corticosteroids). UC presents more with extensive disease not paralleled in severity clinically or histologically, follows benign course with easy medical control and low incidence of fulminant disease, cancer, complications, and surgery. UC related colorectal cancer develop in an unpredictable manner with respect to disease duration and site questioning the validity of strict screening protocol. About a third of CD patients get antituberculosis drugs and a significant number presents with small intestinal bleed which is predominantly afflicted by aggressive inflammation. Biomarkers have inadequate diagnostic sensitivity and specificity for both. Pediatric IBD tends to be more severe than adult. Population based studies are needed to address the lacunae in epidemiology and definition of etiological factors. Newer biomarkers and advanced diagnostic techniques (in the field of gastrointestinal endoscopy, molecular pathology and genetics) needs to be developed for proper disease definition and treatment.

TMC-SNPdb: an Indian germline variant database derived from whole exome sequences

Cancer is predominantly a somatic disease. A mutant allele present in a cancer cell genome is considered somatic when it's absent in the paired normal genome along with public SNP databases. The current build of dbSNP, the most comprehensive public SNP database, however inadequately represents several non-European Caucasian populations, posing a limitation in cancer genomic analyses of data from these populations. We present the T: ata M: emorial C: entre-SNP D: ata B: ase (TMC-SNPdb), as the first open source, flexible, upgradable, and freely available SNP database (accessible through dbSNP build 149 and ANNOVAR)-representing 114 309 unique germline variants-generated from whole exome data of 62 normal samples derived from cancer patients of Indian origin. The TMC-SNPdb is presented with a companion subtraction tool that can be executed with command line option or using an easy-to-use graphical user interface with the ability to deplete additional Indian population specific SNPs over and above dbSNP and 1000 Genomes databases. Using an institutional generated whole exome data set of 132 samples of Indian origin, we demonstrate that TMC-SNPdb could deplete 42, 33 and 28% false positive somatic events post dbSNP depletion in Indian origin tongue, gallbladder, and cervical cancer samples, respectively. Beyond cancer somatic analyses, we anticipate utility of the TMC-SNPdb in several Mendelian germline diseases. In addition to dbSNP build 149 and ANNOVAR, the TMC-SNPdb along with the subtraction tool is available for download in the public domain at the following:Database URL: http://www.actrec.gov.in/pi-webpages/AmitDutt/TMCSNP/TMCSNPdp.html.

Genetic association meta-analysis: a new classification to assess ethnicity using the association of MCP-1 -2518 polymorphism and tuberculosis susceptibility as a model

Background

In meta-analyses of genetic association studies, ancestry and ethnicity are not accurately investigated. Ethnicity is usually classified using conventional race/ethnic categories or continental groupings even though they could introduce bias increasing heterogeneity between and within studies; thus decreasing the external validity of the results. In this study, we performed a meta-analysis using a novel ethnic classification system to test the association between MCP-1 -2518 polymorphism and pulmonary tuberculosis. Our new classification considers genetic distance, migration and linguistic origins, which will increase homogeneity within ethnic groups.

Methods

We included thirteen studies from three continents (Asia, Africa and Latin America) and considered seven ethnic groups (West Africa, South Africa, Saharan Africa, East Asia, South Asia, Persia and Latin America).

Results

The results were compared to the continental group classification. We found a significant association between MCP-1 -2518 polymorphism and TB susceptibility only in the East Asian and Latin American groups (OR 3.47, P = 0.08; OR 2.73, P = 0.02). This association is not observed in other ethnic groups that are usually considered in the Asian group, such as India and Persia, or in the African group.

Conclusions

There is an association between MCP-1 -2518 polymorphism and TB susceptibility only in the East Asian and Latin American groups. We suggest the use of our new ethnic classification in future meta-analysis of genetic association studies when ancestry markers are not available. This new classification increases homogeneity for certain ethnic groups compared to the continental classification. We recommend considering previous data about migration, linguistics and genetic distance when classifying ethnicity in further studies.

Influence of dihydrofolate reductase gene polymorphisms rs408626 (-317A>G) and rs442767 (-680C>A) on the outcome of methotrexate-based maintenance therapy in South Indian patients with acute lymphoblastic leukemia

PURPOSE

The most common cause of treatment failure in acute lymphoblastic leukaemia (ALL) is the relapse. Genetic polymorphisms of dihydrofolate reductase (DHFR) enzyme affect the response to methotrexate (MTX) treatment. Inter-individual variability exists in the distribution of DHFR variants, and they influence MTX treatment outcome. To the best of our knowledge, there are no genetic studies reported from India, which have explored the influence of DHFR variants on the outcome of MTX treatment. Therefore, we aim to study the influence of DHFR rs408626 (-317A>G) and rs442767 (-680C>A) variants on ALL outcome in South Indian patients.

METHODS

A total of 70 ALL patients who were on MTX-based maintenance therapy were recruited for the study. DNA was extracted from leukocytes, and genotyping was done by real-time PCR.

RESULTS

The DHFR-317GG genotype was associated with the increased risk of relapse in patients with ALL (relative risk 2.25, 95% confidence interval (CI) 1.38 to 3.6, p = 0.02). DHFR-317AA and -680CA genotypes were found to be associated with severe leucopenia (p < 0.05). In Cox regression model, -317GG genotype was found to have lower relapse-free survival (hazard ratio (HR) 2.56, 95% CI 1.06 to 6.19, p = 0.03) and overall survival (HR 3.72, 95% CI 1.44 to 9.65, p = 0.007). Similarly, patients with white blood cell (WBC) count >50,000 cells/mm(3) were also found to have lower relapse-free survival (HR 2.20, 95% CI 1.10 to 4.79, p = 0.04) and overall survival (HR 3.30, 95% CI 1.45 to 7.53, p = 0.004).

CONCLUSION

The GG genotype of DHFR-317A>G variant is associated with increased risk of ALL relapse and lower overall survival in South Indian population. Both variants of DHFR (-317 AA and -680 CA) are found to be associated with severe leucopenia caused by MTX.

A study of genetic polymorphisms in mitochondrial DNA hypervariable regions I and II of the five major ethnic groups and Vedda population in Sri Lanka

Diversity of the hypervariable regions (HV) I and II of the mitochondrial genome was studied in maternally unrelated Sri Lankans (N=202) from six ethnic groups (i.e.: Sinhalese, Sri Lankan Tamil, Muslim, Malay, Indian Tamil and Vedda). DNA was extracted from blood and buccal swabs and HVI and HVII regions were PCR amplified and sequenced. Resulting sequences were aligned and edited between 16024-16365 and 73-340 regions and compared with revised Cambridge reference sequences (rCRS). One hundred and thirty-five unique haplotypes and 22 shared haplotypes were observed. A total of 145 polymorphic sites and 158 polymorphisms were observed. Hypervariable region I showed a higher polymorphic variation than hypervariable region II. Nucleotide diversities were quite low and similar for all ethnicities apart from a slightly higher value for Indian Tamils and a much lower value for the Vedda population compared to the other groups. When the total population was considered South Asian (Indian) haplogroups were predominant, but there were differences in the distribution of phylo-geographical haplogroups between ethnic groups. Sinhalese, Sri Lankan Tamil and Vedda populations had a considerable presence of West Eurasian haplogroups. About 2/3rd of the Vedda population comprised of macro-haplogroup N or its subclades R and U, whereas macro-haplogroup M was predominant in all other populations. The Vedda population clustered separately from other groups and Sri Lankan Tamils showed a closer genetic affiliation to Sinhalese than to Indian Tamils. Thus this study provides useful information for forensic analysis and anthropological studies of Sri Lankans.

Allele and genotype distributions of DNA repair gene polymorphisms in South Indian healthy population

Various DNA repair pathways protect the structural and chemical integrity of the human genome from environmental and endogenous threats. Polymorphisms of genes encoding the proteins involved in DNA repair have been found to be associated with cancer risk and chemotherapeutic response. In this study, we aim to establish the normative frequencies of DNA repair genes in South Indian healthy population and compare with HapMap populations. Genotyping was done on 128 healthy volunteers from South India, and the allele and genotype distributions were established. The minor allele frequency of Xeroderma pigmentosum group A (XPA) G23A, Excision repair cross-complementing 2 (ERCC2)/Xeroderma pigmentosum group D (XPD) Lys751Gln, Xeroderma pigmentosum group G (XPG) His46His, XPG Asp1104His, and X-ray repair cross-complementing group 1 (XRCC1) Arg399Gln polymorphisms were 49.2%, 36.3%, 48.0%, 23.0%, and 34.0% respectively. Ethnic variations were observed in the frequency distribution of these polymorphisms between the South Indians and other HapMap populations. The present work forms the groundwork for cancer association studies and biomarker identification for treatment response and prognosis.

Organization for rare diseases India (ORDI) - addressing the challenges and opportunities for the Indian rare diseases' community

In order to address the unmet needs and create opportunities that benefit patients with rare disease in India, a group of volunteers created a not-for-profit organization named Organization for Rare Diseases India (ORDI; www.ordindia.org). ORDI plans to represent the collective voice and advocate the needs of patients with rare diseases and other stakeholders in India. The ORDI team members come from diverse backgrounds such as genetics, molecular diagnostics, drug development, bioinformatics, communications, information technology, patient advocacy and public service. ORDI builds on the lessons learned from numerous similar organizations in the USA, European Union and disease-specific rare disease foundations in India. In this review, we provide a background on the landscape of rare diseases and the organizations that are active in this area globally and in India. We discuss the unique challenges in tackling rare diseases in India, and highlight the unmet needs of the key stakeholders of rare diseases. Finally, we define the vision, mission, goals and objectives of ORDI, identify the key developments in the health care context in India and welcome community feedback and comments on our approach.

Inherited arrhythmia syndromes leading to sudden cardiac death in the young: a global update and an Indian perspective

Inherited primary arrhythmias, namely congenital long QT syndrome, Brugada syndrome and catecholaminergic polymorphic ventricular tachycardia, account for a significant proportion of sudden cardiac deaths in young and apparently healthy individuals. Genetic testing plays an integral role in the diagnosis, risk-stratification and treatment of probands and family members. It is increasingly obvious that collaborative efforts are required to understand and manage these relatively rare but potentially lethal diseases. This article aims to update readers on the recent developments in our knowledge of inherited arrhythmias and to lay the foundation for a national synergistic effort to characterize them in the Indian population.