The spatial epidemiology of sickle-cell anaemia in India

Abstract

Sickle-cell anaemia (SCA) is a neglected chronic disorder of increasing global health importance, with India estimated to have the second highest burden of the disease. In the country, SCA is particularly prevalent in scheduled populations, which comprise the most socioeconomically disadvantaged communities. We compiled a geodatabase of a substantial number of SCA surveys carried out in India over the last decade. Using generalised additive models and bootstrapping methods, we generated the first India-specific model-based map of sickle-cell allele frequency which accounts for the district-level distribution of scheduled and non-scheduled populations. Where possible, we derived state- and district-level estimates of the number of SCA newborns in 2020 in the two groups. Through the inclusion of an additional 158 data points and 1.3 million individuals, we considerably increased the amount of data in our mapping evidence-base compared to previous studies. Highest predicted frequencies of up to 10% spanned central India, whilst a hotspot of ~12% was observed in Jammu and Kashmir. Evidence was heavily biased towards scheduled populations and remained limited for non-scheduled populations, which can lead to considerable uncertainties in newborn estimates at national and state level. This has important implications for health policy and planning. By taking population composition into account, we have generated maps and estimates that better reflect the complex epidemiology of SCA in India and in turn provide more reliable estimates of its burden in the vast country. This work was supported by European Union’s Seventh Framework Programme (FP7//2007–2013)/European Research Council [268904 – DIVERSITY]; and the Newton-Bhabha Fund [227756052 to CH]

Temporal trends and differential patterns in the prevalence of severe anaemia in India: observations from country‐wide haemoglobin determinations 2008–2018

“…However, the most common genetic disorder of haemoglobin in the Northeast is HbE trait , which is usually benign and does not cause significant suppression of Hb levels unless occurring in conjunction with other Hb variants (compound heterozygotes). Sickle cell anaemia and β ‐thalassaemia syndromes are less prevalent in Northeast India than in the other zones .…”

“…Malaria is endemic in India and may be an important cause of severe anaemia, especially in the high‐transmission states of the Central (Madhya Pradesh, Chhattisgarh), East (Bihar, Jharkhand) and Northeast (Tripura, Assam, Meghalaya, Mizoram, Arunachal Pradesh) zones . Central India is also a hotspot for sickle cell haemoglobin; and there are foci in the West, North and South zones that may have been partly responsible for the high load of severe anaemia in these areas. However, the most common genetic disorder of haemoglobin in the Northeast is HbE trait , which is usually benign and does not cause significant suppression of Hb levels unless occurring in conjunction with other Hb variants (compound heterozygotes).…”

Review: Understanding Rare Genetic Diseases in Low Resource Regions Like Jammu and Kashmir – India

“…Since past few years, a number of suspected cases of genetic disorders (including new/known monogenic diseases and other known genetic diseases with atypical clinical features) have been reported from J&K region. Cases of chromosomal genetic disorders (such as Down Syndrome, Turner Syndrome, Klinefelter Syndrome, Patau Syndrome; Table 5), anemias, blood disorders (including Thalassemia), congenital anomalies, disorders of sex development, metabolic disorders like G6PD deficiency, neurological disorders (Table 6) and others are frequently reported in J&K (Razdan et al, 1994;Kumar et al, 2010;Upma et al, 2010;Vasudev and Sawhney, 2014;Ara et al, 2018;Dar et al, 2018;Hockham et al, 2018). The detrimental effects of consanguinity and inbreeding depression on child health and mortality, cognitive behavior and fertility and an increased risk of cardiovascular diseases in small population groups from J&K has also been reported (Bhasin and Nag, 2002b;Afzal, 2014a,b, 2016;.…”

Spatio-Temporal Epidemiological Analyses of Sickle Cell Disorder of a Tribal Region in Odisha, India

“…The global burden of SCD is increasing and the annual number of affected newborns may be expected to increase approximately from 300,000 to more than 400,000 between 2010 and 2050. In Sub-Saharan Africa the incidence is more than other, but the highest allelic frequencies have been reported in Indian populations (Hockham et al,2018). India has been ranked as the second worst affected country in terms of predicted SCD births (Piel et al, 2013).…”