The causes of the various types of maturity-onset diabetes of the young (MODY) have been traced back to defects at the molecular level of several different genes. Diagnosis of MODY thus can involve genetic testing.

The children of a person with MODY have a 50 percent chance of developing this uncommon form of diabetes. As a comparison, the children of a person with type 2 diabetes have a 1-in-7 chance of developing type 2 diabetes if the parent was diagnosed before the age of 50 and a 1-in-13 chance if their parent was diagnosed after age 50, according to the American Diabetes Association.

The first MODY gene was discovered in 1992. Scientists continue to identify additional genes. Some cases of MODY involve a gene that has not yet been implicated. It is believed that as many as 10 to 12 genes play a role in the development of MODY.

Race, ethnicity and nationality may be risk factors for MODY. Some researchers have reported an above-normal prevalence in black Americans and in Romanians. In addition, many cases of MODY in Chinese and Japanese patients are reported to be caused by genes that have not yet been identified.