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Maturity-Onset Diabetes of the Young
What does Maturity-Onset Diabetes of the Young (MODY) look like?
Determining which type of diabetes a patient has is critical in providing the proper care and treatment. However, a rise in childhood obesity has made distinguishing between type 1 and type 2 diabetes increasingly more challenging.4 Additionally, MODY is often misdiagnosed as Type 1 or Type 2 diabetes due to the similarities in clinical presentation.5 In fact, up to 95% of MODY diabetes cases are misdiagnosed, and these patients may receive inappropriate treatment.2,5
According to the American Diabetes Association, physicians should consider testing patients who were diagnosed in youth or early adulthood and have a strong family history of diabetes. Additionally, patients who were diagnosed with diabetes in youth or early adulthood, but do not present with typical features of Type 1 or Type 2 diabetes, may also benefit from testing. Patients with atypical characteristics may3:
- Be diagnosed with Type 1 diabetes, but test negative for diabetes-associated autoantibodies
- Be diagnosed with Type 2 diabetes, but are not obese and/or do not have a sedentary lifestyle
- Have stable, mild fasting hyperglycemia at diagnosis
- Have stable HbA1c between 5.6 and 7.6% at diagnosis
Most people diagnosed with MODY have impaired insulin secretion and typically experience onset before they are 25 years old.3 The four most common forms of MODY are caused by mutations in HNF1A (MODY3), GCK (MODY2), HNF4A (MODY1), and HNF1B (MODY5).3,6
Depending on the form of MODY, patients may be able to switch from potentially painful and expensive insulin injections to an oral medication, which is typically less expensive and may be a more appealing option to most patients.2 In addition to optimizing treatment, correctly diagnosing MODY can assist in diagnosing other affected family members and predicting the prognosis of the disease.3 A specific MODY diagnosis can also explain symptoms other than diabetes and allow for increased surveillance of associated complications.3
Maturity-Onset Diabetes of the Young (MODY) Genetic Profile
Maturity-onset diabetes of the young (MODY) is a suspected diagnosis in young non-obese patients who lack an autoimmune cause for diabetes and who have a family history of diabetes in successive generations. The majority of MODY cases are due to mutations in one of four genes. Identifying a mutation in one of these MODY genes can lead to improved treatment, increased surveillance for related symptoms, and earlier detection in currently asymptomatic family members. GCK encodes the enzyme glucokinase, a key regulator of glucose metabolism in pancreatic beta cells. The three HNF (hepatic nuclear factor) genes encode transcription factors that regulate gene expression in the pancreas.
Sanger sequencing and MLPA
- Centers for Disease Control and Prevention. National Diabetes Statistics Report, 2017: Estimates of diabetes and its burden in the United States. 2017. https://www.cdc.gov/diabetes/pdfs/data/statistics/national-diabetes-statistics-report.pdf. Accessed May 1, 2019.
- Kleinberger, JW, Pollin, TI. Undiagnosed MODY: Time for action. Curr Diab Rep. 2015 December; 15(12):110.
- American Diabetes Association. 2. Classification and Diagnosis of Diabetes: Standards of Medical Care in Diabetes—2019. Diabetes Care. 2019;42(Supplement 1):S13-S28. doi:10.2337/dc19-S002
- Chiang JL, Maahs DM, Garvey KC, et al. Type 1 Diabetes in Children and Adolescents: A Position Statement by the American Diabetes Association. Dia Care. 2018;41(9):2026-2044. doi:10.2337/dci18-0023
- Pihoker C, Gilliam LK, Ellard S, et al. Prevalence, characteristics and clinical diagnosis of maturity onset diabetes of the young due to mutations in HNF1A, HNF4A, and glucokinase: Results from the SEARCH for diabetes in youth. J Clin Endocrinol Metab. 2013;98(10):4055-4062. doi:10.1210/jc.2013-1279
- Naylor R, Knight Johnson A, del Gaudio D. Maturity-Onset diabetes of the young overview. In: Adam MP, Ardinger HH, Pagon RA, et al., eds. GeneReviews®. Seattle (WA): University of Washington, Seattle; 1993. http://www.ncbi.nlm.nih.gov/books/NBK500456/. Accessed May 1, 2019.