Do Indians have a genetic propensity for heart disease?

India is reeling under the burden of cardiovascular diseases. And the numbers speak for themselves. Indians constitute a fifth of global deaths from heart disease and we are 3-20 times at higher risk of developing heart disease compared to others. While 23 per cent of deaths before the age of 70 occur due to heart disease and stroke in a Western population, it is a staggering 52 per cent among Indians. Indians develop heart disease earlier by 5-10 years compared to other ethnic populations.

Is this skew of coronary artery heart disease-related death rate towards Indians indicative that we could be genetically pre-disposed to heart disease?

Even though instances of direct evidence are few, there are indirect ones suggesting significant genetic influence of genes in causing heart disease. For example, identical twins show genetic effect in developing heart disease and heredity plays a role, with 40-60 per cent risk of heart disease in children if either or both parents have heart disease.

Though many genes have been investigated, very few have been confirmed to cause heart disease. There are infrequent examples of single genes playing a role in causing heart disease. Genetics could also be playing a role in increasing risk of developing heart disease when some ‘risk associated genes’ are present with other environmental factors.

Genetic variations

More recently, a September 2018 IIT Madras study, in the Journal of Biological Chemistry outlines an analysis of genomic DNA samples from over 750 individuals from the Indian population — it outlines that 35 to 40 per cent Indians carry a set of genetic variations that puts them at higher risk of heart disease.

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While such studies could significantly serve as a beacon towards understanding the genetic basis of cardiovascular and metabolic diseases in India, heart disease is caused by multiple factors of which environmental factors like tobacco use, diabetes, and lifestyle play a large role. High stress levels, lack of exercise, a poor, fibre-deficient, high carbohydrate, diet, not monitoring health parameters regularly and propensity to binge on sweets and fast foods could be just some of them.

Region-wise differences

Between 1990 and 2016, heart disease in India rose by around 34 per cent from 155.7 deaths to 209.1 deaths, per one lakh population. This data, drawn from the Public Health Foundation of India, among others, further elaborates that there are differences even within India, region-wise — for instance, Punjab has the highest burden of ischemic heart disease and Mizoram has the lowest. There is also a difference between rural and urban India, with prevalence of heart disease among rural population being half of that among the urban population. Even that is changing, with recent studies showing increasing incidence of heart disease among the rural population. To add genetics to this cauldron would be ringing the death knell.

Interestingly, while the incidence of heart disease in India has increased significantly, there is a decline in heart disease among Indians internationally, indicating that it is not all genetics.

Control of environmental factors like leading an active physical life-style, a balanced diet of vegetables, fruit, complex carbohydrate, avoiding tobacco, and treatment of risk factors like diabetes and high blood pressure can significantly reduce the risk of developing heart disease, among Indians.

The writer is a cardiovascular thoracic surgeon andVice-Chairman of Asian Heart Institute, Mumbai