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Genetic and Rare Diseases Information Center (GARD)

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Monogenic diabetes

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* Not a rare disease
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Your Question

My daughter was diagnosed with type 1 diabetes at the age of three. We recently learned that she may, instead, have monogenic diabetes. I have never heard of monogenic diabetes and would like to learn more.

Our Answer

We have identified the following information that we hope you find helpful. If you still have questions, please contact us.

What is monogenic diabetes?

The most common forms of diabetes, type 1 and type 2, are polygenic, meaning the risk of developing these forms of diabetes is related to multiple genes [1][2]. Environmental factors, such as obesity in the case of type 2 diabetes, also play a part in the development of polygenic forms of diabetes. Polygenic forms of diabetes often run in families. Doctors diagnose polygenic forms of diabetes by testing blood glucose in individuals with risk factors or symptoms of diabetes [1].

Some rare forms of diabetes result from mutations in a single gene and are called monogenic [1][2]. Monogenic forms of diabetes may account for about 1 to 5 percent of all cases of diabetes in young people [1]. In some cases of monogenic diabetes, the gene mutation is inherited; but in others, the gene mutation develops spontaneously [1][2]. Most mutations in monogenic diabetes reduce the body's ability to produce insulin, a protein produced in the pancreas that is essential for the body to use glucose for energy [1][2]. As a result, monogenic diabetes can easily be mistaken for type 1 diabetes [2].

Last updated: 9/23/2011

What are the types of monogenic diabetes?

Permanent neonatal diabetes mellitus (PND), transient neonatal diabetes (TND), and maturity-onset diabetes of the young (MODY) are the main forms of monogenic diabetes. These forms of diabetes can include a group of different genes; some respond to treatment, while others are mild and should not be treated. MODY is the more common form. PND and TND first occur in newborns and young infants; MODY usually first occurs in children or adolescents but may be mild and not detected until adulthood [2].
Last updated: 8/14/2008

It monogenic diabetes a new condition? When was it discovered and unveiled?

Since 1992, numerous genetic subtypes of diabetes have been described in which gene mutations result in diabetes primarily through β-cell dysfunction. This knowledge means that patients who were previously categorized clinically as having maturity-onset diabetes of the young (MODY), Permanent neonatal diabetes mellitus  (PNDM) or transient neonatal diabetes (TNM) can now usually be classified by genetic subgroup. Definition of the genetic subgroup can result in appropriate treatment, genetic counseling and prognostic information. [3]

After many years of effort with only modest result, the last 5 years has seen a tremendous surge in our understanding of the genetics of diabetes. [4]

Last updated: 8/14/2008

It is my understanding that monogenic diabetes is primarily genetic and confirmed through genetic testing. If my daughter's test result rules out genetics, is there another test for spontaneous mutations? Or would we assume that a negative result means that she has type 1 diabetes?

While in Type 1 and Type 2 diabetes there is no single diagnostic test, this is not the case in monogenic diabetes where in >80% of cases a molecular genetic diagnosis can be made by DNA testing. [5] In some cases of monogenic diabetes, the gene mutation is inherited; in others, the gene mutation develops spontaneously. [1][2] The same genetic test can be used for both types of mutations, regardless of whether the mutation was inherited from a parent or occurred spontaneously in that individual. 
 
Based on the results of genetic testing, you should discuss with your daughter's physician and/or a genetics professional recommendations about how to proceed.
Last updated: 8/14/2008

Who should be tested for monogenic diabetes?

Genetic testing can diagnose many forms of monogenic diabetes. You might want to consider testing for monogenic diabetes if you or a family member was diagnosed with diabetes during the first six months of life; there is familial diabetes with a parent affected; there is mild fasting hyperglycemia (high blood sugar), especially if young or familial; and/or there is diabetes associated with extra pancreatic features.[6] 

Some tests that help differentiate monogenic diabetes from type 1 diabetes are simple and relatively inexpensive; parents of children who were diagnosed with type 1 diabetes at an early age should discuss with their physician whether such a test was conducted at the time of diagnosis, as such testing may not have been done[6].

A correct diagnosis that allows the proper treatment to be selected should lead to better glucose control and improved health in the long term. Testing of other family members may also be indicated to determine whether they are at risk for diabetes [6].

Last updated: 9/23/2011

How is testing for monogenic diabetes done?

Testing for monogenic diabetes involves providing a blood sample from which DNA is isolated. The DNA is analyzed for changes in the genes that cause monogenic diabetes. Abnormal results can determine the gene responsible for diabetes in a particular individual or show whether someone is likely to develop a monogenic form of diabetes in the future. Genetic testing can also be helpful in selecting the most appropriate treatment for individuals with monogenic diabetes. Prenatal testing can diagnose these conditions in unborn children [1].

Most forms of monogenic diabetes are caused by dominant mutations, meaning that the condition can be passed on to children when only one parent is affected. In contrast, if the mutation is a recessive mutation, a disease gene must be inherited from both parents for diabetes to occur. For recessive forms of monogenic diabetes, testing can indicate whether parents or siblings without disease are carriers for recessive genetic conditions that could be inherited by their children [1]

If you suspect that you or a member of your family may have a monogenic form of diabetes, you should seek help from your health care professional or a genetic counselor. These healthcare professionals, who are familiar with your medical and family history, can determine whether genetic testing is appropriate, select the genetic tests that should be performed, and provide information about the basic principles of genetics, genetic testing options, and confidentiality issues. They also can review the test results and management options with you [1][7].

More information about the laboratories that conduct testing for monogenic diabetes can be found at the following link: http://www.monogenicdiabetes.org/howcan.html

You can learn about additional laboratories which offer testing by visiting GeneTests. By providing current, authoritative information on genetic testing and its use in diagnosis, management, and genetic counseling, GeneTests promotes the appropriate use of genetic services in patient care and personal decision making. To access information about testing for monogenic types of diabetes, visit the GeneTests home page (http://www.genetests.org/) and click on the "Laboratory Directory" icon. Enter "diabetes" in the search box and then scroll to the entries for transient neonatal diabetes mellitus, maturity-onset diabetes of the young, and/or permanent neonatal diabetes mellitus. As mentioned above, a genetic professional or other healthcare provider can help you to navigate through the various testing options to determine which would be most appropriate for your family. 

Last updated: 9/23/2011

How is treatment for monogenic diabetes different than for other types of diabetes?

There are many forms of monogenic diabetes, and these are due to mutations in different genes. Recent research results show that people with certain forms of monogenic diabetes can be treated with oral diabetes medications instead of insulin injections [1].

People with monogenic forms of diabetes still need to check their blood sugar levels, however, they may not need to check as often as a person with type 1 diabetes [8].

Last updated: 9/23/2011

Who can I contact to learn more about monogenic diabetes?

You can contact the National Diabetes Information Clearinghouse (NDIC), a service of the National Institute of Diabetes & Digestive & Kidney Diseases (NIDDK), for more information on monogenic diabetes. An online resource about monogenic diabetes is available at the following link. 
http://diabetes.niddk.nih.gov/dm/pubs/mody/

National Diabetes Information Clearinghouse (NDIC)
1 Information Way
Bethesda, MD 20892-3560
Toll free:  800-860-8747
Fax:  703-738-4929
E-mail form:   http://diabetes.niddk.nih.gov/about/contact.htm
Web site:   http://diabetes.niddk.nih.gov/
Last updated: 8/14/2008

References