MODY and neonatal diabetes
Diabetes is a complex and diverse disease, where both genetic factors, lifestyle and the environment play important roles. There are several different forms of diabetes, were age of onset, symptoms, prognosis and treatment vary between the different types. Despite this, it is sometimes difficult to find the correct diagnosis in a clinical setting.
Diabetes is commonly classified into four main groups, namely type 1 diabetes, type 2 diabetes, gestational diabetes and other specific forms of diabetes. The two most prevalent forms are type 1 diabetes and type 2 diabetes, constituting 5-10% and 90-95% of all diabetes cases, respectively. These two types usually have minimal clinical overlap and may be distinguished from each other clinically with relatively simple examinations and tests. Other specific forms of diabetes, on the other hand, may have overlapping characteristics with both type 1 and type 2 diabetes, and are thus not that easy to diagnose correctly. This group includes both secondary forms of diabetes, caused as a result of other diseases and conditions, as well as monogenic diabetes.
Monogenic diabetes is caused by mutations in one gene, and make up about 2-3% of all diabetes cases. This group includes mitochondrial diabetes, neonatal diabetes and maturity-onset diabetes of the young (MODY).
MODY usually affect younger people (age of onset before 25-35 years) and is characterized by progressive dysfunction of the insulin-producing cells in the pancreas. It is an autosomal dominant disease, meaning that if one of your parents has MODY, you have a 50% possibility to inherit the defect gene, and your children will have the same possibility of inheriting the disease from you. MODY is subdivided into multiple groups depending on the gene involved, and today we recognize a total of 14 genes associated with different types of MODY. Mutations in the HNF1A, GCK, HNF4A and HNF1B genes together constitute 90% of all cases. As mutations in different genes confer variations in disease development and symptoms, a precise diagnosis is essential in order to provide the correct treatment and prognosis.
Most patients with neonatal diabetes are diagnosed before the age of 6 months. Neonatal diabetes can be either transient (TNDM) or permanent (PNDM), and may be caused by mutations in one of about 30 different known genes. Several of these mutations typically occur spontaneously. This means that either parent has diabetes, but the patient may pass the mutation down to future generations. Even though the neonatal diabetes is rare (about 1 in 100,000), a precise diagnosis is still of utmost importance for the individual patient, as this largely affects the choice of treatment.
At Center for Diabetes Research we perform diagnostics in regards to MODY and neonatal diabetes in close collaboration with the Department of Medical Genetics (MGM) at Haukeland University Hospital. Patients with a family history of diabetes in multiple generations, where diabetes has occurred before 25 years of age, and where there is reduced insulin secretion (treated with insulin, tablets or diet), are candidates for testing.
Do you meet these requirements? Then you may want to talk to your doctor about genetic testing. All inquiries have to be done by a doctor (requester) who has to include a completed diagnostic form. Please download the diagnostic form and bring it to your doctor so you can look at this together. It is appreciated if the consent form is also filled in and included, so that the sample can be used in research if it is negative for the already known genes. Both the diagnostic form and consent form can be sent to us together with 7 ml EDTA-blood (4 ml accepted for children) and 8 ml serum on gel glass. It is important that the test tubes are packed in a sealed container to avoid spilling during transport. The tubes should be marked with date, patient name and identity number. Remember yellow sticky note with suspected blood contamination. The package may be sent by priority mail, but avoid shipping over weekends. Express mail is not necessary.
The diagnostic form and consent form are available at www.mody.no. This website also contains more information about MODY and other rare types of diabetes.
In Bergen we archive clinical information and DNA from over 250 Norwegian families with a MODY diagnosis (850 families in total). We have consent from the Norwegian Data Protection Authority to store information and DNA. A research group has been established, under the leadership of Professor Pål R. Njølstad, were the research is based in this data. Among other things, the research group has contributed to the mapping of the PNDM2 and PNDM3 genes, as well as the diabetes types MODY2, 3 and 5.
For more information or questions, contact:
Pål R. Njølstad (physician)
Janne Molnes (molecular biologist)
Helge Ræder (physician)