Times of India
18 November 2010
By Pushpa Narayan

A recent study by a city–based research centre has found a growing number of children and young adults with type–2 diabetes, once found only in adults. This has sent doctors...
Is there a hidden gene that triggers diabetes in children and young adults in India? Diabetologists are on the look–out for a desi gene after some studies have suggested that such an elusive gene could be triggering the disorder in young people.

"Diabetes in itself was a rare disease among the youth until the late 1970s. If we saw 200 diabetics, we would see one under the age of 25. Even this patient would be an insulin–dependent diabetic, commonly called the type–1. Today, in every 100 patients, we find that at least three are under the age of 25. But 60% of them do not have type–1 diabetes, but type–2 diabetes, once seen only in adults," said Dr V Mohan, chairman Madras Diabetes Research Foundation.

If both parents are diabetic and the child is obese, then chances are that he/she could have an early onset of type–2 diabetes. "In this case, a genetic test would show involvement of multiple gene mutations that may have caused the disorder. But in some other cases, we see an involvement of just one gene. And in this case just one parent is diabetic, obesity and metabolic syndrome is absent. We call this the ‘maturity onset diabetes of the young’ (MODY). This differentiation between early onset of type–2 and MODY is crucial, since the medicines for the two differ.

There are six established sub–types of MODY, of which sub–types 1 and 3 are common. A recent study published in medical journal ‘Clinical Genetics’ has shown that commonly spotted genetic strains among diabetic children in the West are rare in Indians.

The Madras Diabetes Research Foundation team screened 96 children, who were suspected to have MODY, based on clinical symptoms. Though nearly 90% of the cases in the West were MODY 1 and 3, studies by the team showed only 9% had MODY 3, 3.4% had MODY –2 and none of them had MODY–1.

"This implies that either the majority of MODY patients in south India have mutations on hitherto unknown MODY gene (MODY X) or that clinically diagnosed MODY subjects might in reality have early onset of type–2 diabetes," said Anuradha Shekher, the first author of the paper, said in the study.

The study’s principal investigator Radha Venkatesan, who heads the department molecular genetics in Madras Diabetes Research Foundation, said, "The next step should be identification of the unknown genes. In case we don’t see any gene, then we could probably conclude it’s the early onset of type–2 diabetes."

Delhi–based diabetologist Dr Anoop Misra of Fortis Hospital said genetics needs to be studied in depth. "Diabetes is a heterogenous disorder, and it is possible that some genes are unknown. We can’t rule out the possibility of an unknown gene," he said.

Not–So–Sweet Childhood
Type–1 Diabetes | This is the most common form of diabetes in children. It is caused by the inability of the pancreas to produce insulin. In such cases, there may not be any family history of diabetes.

Symptoms are frequent urination, fatigue and vomitting along with high sugar level

Type–2 Diabetes | This is common among adults. It is also known as non–insulin dependent diabetes or adult–onset diabetes. People with type 2 diabetes do not usually require injections of insulin. Controlling blood glucose level by watching the diet and exercising regularly can remedy the problem

On Thin Ice
Maturity Onset Diabetes of the Young (MODY)
Only one parent affected but usually grand parents and great grand parents have it Monogenic (only 1 gene involved) Obesity absent Insulin secretory defect Acanthosis nigricans absent Polycystic ovarian syndrome absent Metabolic syndrome absent

Early onset type–2 Diabetes
Both the parents usually affected
Polygenic (multiple genes) Obesity present Insulin resistance is main defect Usually present May be present Present