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Testing for Neonatal Diabetes and MODY

MODY can be caused by mutations in any one of more than 10 genes, while over 20 genes have been associated with monogenic neonatal diabetes. Each course of treatment is different, depending on the genes involved and other factors.

The only way to know if someone has monogenic diabetes is to have genetic testing.  This involves collecting either a blood or saliva sample and sending it to a laboratory for testing.  The sample is used to make DNA and gene sequencing is performed.  Sequencing is the process by which the order of the bases or “letters” in a stretch of DNA making up a gene is determined.  The order of bases in a person undergoing genetic testing is compared to the correct order for each gene being tested.  If a difference is found, it is known as a mutation.  Surprisingly, not all mutations will actually cause diabetes.  Therefore, it is very important that results of genetic testing are discussed with your doctor to understand if a reported mutation is the cause of diabetes.

Genetic testing is much more labor intensive than routine blood work tests.  Thus, it often takes weeks to months before results of genetic testing are known.

If a gene mutation is found that is causing diabetes, it is important to discuss with your physician if other family members should also be tested to determine if they have the gene mutation.  For instance, because MODY is autosomal dominant meaning that only 1 of the 2 copies of a gene needs to carry a mutation in order to cause diabetes, each first degree relative of an affected person has a 50% chance of carrying the same gene mutation.  If they carry the gene mutation, they have  a >95% chance of developing MODY at some time in their life.

If you or a loved one has MODY, it is crucial to be under the care of a knowledgeable specialist. He or she will work with you to determine the most appropriate course of treatment.