CHENNAI: When 16-year-old Haritha was taken to her family physician for treatment of a boil that did not heal for long, she didn't realize it was the beginning of a journey that would turn her family's life upside down. Her blood test revealed that she was diabetic. The physician referred her to a diabetes centre for further investigation.

Doctors at the centre not only confirmed that Haritha had the disorder, but also that her younger sister, Harini, was diabetic. The Madras Diabetes Research Foundation, attached to the hospital, zeroed in on the cause ?a genetic mutation, traced for the first time.

“It was not the commonly seen Type 1 or Type 2 diabetes. We found that the girls and six other family members had MODY (maturity-onset diabetes of the young). And the mutations had occurred in the gene involved in controlling insulin production,?said diabetologist Dr V Mohan. The study has been published in the Journal of Clinical Endocrinology and Metabolism.

MODY is a hereditary form of diabetes caused by genetic changes that lead to disruption of insulin production and, therefore, an increase in sugar levels in the blood. In this type, children inherit the mutated gene from one of the parents.

There are six types of MODY and treatment and symptoms of each type vary. Of the six types, the first three (MODY 1-3) are common. “All the eight members of the family had MODY 3 but the gene mutation they had was new. Here there is a change in one amino acid,?said V Radha, who heads the department of genetics at the Madras Diabetes Research Foundation.