The existence of Rajasthan’s nomadic Raika tribe revolves around its camels. Of the belief that the god Shiva bestowed upon them the earthly task of tending to camels, Raikas herd the dromedaries through the western deserts. Camels for them are a source of nutrition and the size of a herd is the measure of prestige. Along their nomadic way, this old community has developed a remarkable immunity to a new-age disease. A new study finds that Raika DNA has a high concentration of the gene for Type 1 diabetes but a negligible rate of incidence of the disease.
Type 1 diabetes is the form of the disease where an autoimmune reaction destroys insulin-producing cells in the body. The resulting insulin shortage leads to high sugar levels, which may lead to acute complications, including heart disease, stroke, kidney failure, foot sores and loss of eyesight. Type 1 diabetes is a genetic disease with a strong association with two genes called HLA-DR3 and HLA-DR4. (HLA stands for human leukocyte antigen.)
In India, the frequency of the HLA-DR3 gene in the general population is about 16% but it occurs in more than 90% of people with Type 1 diabetes. HLA-DR4-related diabetes is common in Caucasian populations but not in India.
A team of scientists from the All India Institute of Medical Sciences, the Indian Council for Medical Research and SP Medical College in Bikaner examined Raika DNA for possible factors underlying their resistance to diabetes. “Our initial hypothesis was that maybe this population does not have the HLA-DR3 gene at all because this gene is so strongly associated with Type 1 diabetes,” said Narinder Mehra, former dean of research at AIIMS. “But to our surprise the gene was about three times more common than in other populations in India. And yet, there is no diabetes.”
Life spent outdoors
Here is an idea of how genetically pre-disposed Raika tribe members are to diabetes. The HLA-DR3 gene frequency in the community is 53% as opposed to 28% in a non-Raika group in Rajasthan and only 15% in the average population of North India. The only other population in the world that has a similar high diabetes gene frequency is in Sardinia, Italy, which, along with Finland, has the world’s most diabetes patients. One reason why the Raikas have so much of HLA-DR3 could be inter-marriage. Like many Indian populations, the Raikas too are a consanguineous community, leading to the gene getting concentrated in Raika DNA.
The researchers say that the Raikas’ environment and lifestyle likely protects them from developing the disease. Members of the tribe are typically tall, thin and lean with no abdominal obesity – quite unlike the stereotype of someone susceptible to diabetes. As they herd camels, Raikas have to walk eight to 10 kilometres every day. The life outdoors exposes them to Vitamin D in sunlight, which is known to be effective in controlling diabetes.
The camel milk theory
The scientists also observed the Raika’s camel milk drinking habits and suggest that the milk is perhaps conferring some diabetes resistance. RP Agarwal of SP Medical College has been conducting clinical, epidemiological and genetic studies on camel milk for the last 15 years. “In one study we saw that, by giving camel milk daily for one or two years, Type 1 diabetic patients start reducing their dose of insulin by 60-70%,” Agarwal said. “Some of them are entirely on camel milk and are not taking insulin now.”
Although no one has isolated any insulin-like compound, Agarwal says camel milk shows insulin-like activity when compared to cow milk. While oral insulin has been a failure because the stomach’s digestive juices destroy the ingested hormone, the properties of camel milk allow it to pass through the stomach and get absorbed by the intestine.
Mehra, however, is not convinced of the camel milk approach. “I am not fully convinced,” he said. “A regular drinker will be one who takes more than 500 ml per day but very few among the new generation drinks that much now. We are not seeing more Type 1 diabetes in the new generation.”
To know what is really going on in the Raika DNA, the next step will be to conduct a genome-wide study and check if other genes confer a protective effect that dilutes the impact of HLA-DR3.
Type 1 diabetes is the form of the disease where an autoimmune reaction destroys insulin-producing cells in the body. The resulting insulin shortage leads to high sugar levels, which may lead to acute complications, including heart disease, stroke, kidney failure, foot sores and loss of eyesight. Type 1 diabetes is a genetic disease with a strong association with two genes called HLA-DR3 and HLA-DR4. (HLA stands for human leukocyte antigen.)
In India, the frequency of the HLA-DR3 gene in the general population is about 16% but it occurs in more than 90% of people with Type 1 diabetes. HLA-DR4-related diabetes is common in Caucasian populations but not in India.
A team of scientists from the All India Institute of Medical Sciences, the Indian Council for Medical Research and SP Medical College in Bikaner examined Raika DNA for possible factors underlying their resistance to diabetes. “Our initial hypothesis was that maybe this population does not have the HLA-DR3 gene at all because this gene is so strongly associated with Type 1 diabetes,” said Narinder Mehra, former dean of research at AIIMS. “But to our surprise the gene was about three times more common than in other populations in India. And yet, there is no diabetes.”
Life spent outdoors
Here is an idea of how genetically pre-disposed Raika tribe members are to diabetes. The HLA-DR3 gene frequency in the community is 53% as opposed to 28% in a non-Raika group in Rajasthan and only 15% in the average population of North India. The only other population in the world that has a similar high diabetes gene frequency is in Sardinia, Italy, which, along with Finland, has the world’s most diabetes patients. One reason why the Raikas have so much of HLA-DR3 could be inter-marriage. Like many Indian populations, the Raikas too are a consanguineous community, leading to the gene getting concentrated in Raika DNA.
The researchers say that the Raikas’ environment and lifestyle likely protects them from developing the disease. Members of the tribe are typically tall, thin and lean with no abdominal obesity – quite unlike the stereotype of someone susceptible to diabetes. As they herd camels, Raikas have to walk eight to 10 kilometres every day. The life outdoors exposes them to Vitamin D in sunlight, which is known to be effective in controlling diabetes.
The camel milk theory
The scientists also observed the Raika’s camel milk drinking habits and suggest that the milk is perhaps conferring some diabetes resistance. RP Agarwal of SP Medical College has been conducting clinical, epidemiological and genetic studies on camel milk for the last 15 years. “In one study we saw that, by giving camel milk daily for one or two years, Type 1 diabetic patients start reducing their dose of insulin by 60-70%,” Agarwal said. “Some of them are entirely on camel milk and are not taking insulin now.”
Although no one has isolated any insulin-like compound, Agarwal says camel milk shows insulin-like activity when compared to cow milk. While oral insulin has been a failure because the stomach’s digestive juices destroy the ingested hormone, the properties of camel milk allow it to pass through the stomach and get absorbed by the intestine.
Mehra, however, is not convinced of the camel milk approach. “I am not fully convinced,” he said. “A regular drinker will be one who takes more than 500 ml per day but very few among the new generation drinks that much now. We are not seeing more Type 1 diabetes in the new generation.”
To know what is really going on in the Raika DNA, the next step will be to conduct a genome-wide study and check if other genes confer a protective effect that dilutes the impact of HLA-DR3.
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