To test, or not to test: time for a MODY calculator?

Abstract

To test, or not to test, that is often the question in diabetes genetics. This is why the paper of Shields et al in the current issue of Diabetologia is so warmly welcomed. MODY is the most common form of monogenic diabetes. Nevertheless, the optimal way of identifying MODY families still poses a challenge both for researchers and clinicians. Hattersley's group in Exeter, UK, have developed an easy-to-use MODY prediction model that can help to identify cases appropriate for genetic testing. By answering eight simple questions on the internet (www.diabetesgenes.org/content/mody-probabilitycalculator), the doctor receives a positive predictive value in return: the probability that the patient has MODY. Thus, the classical binary (yes/no) assessment provided by clinical diagnostic criteria has been substituted by a more rational, quantitative estimate. The model appears to discriminate well between MODY and type 1 and type 2 diabetes when diabetes is diagnosed before the age of 35 years. However, the performance of the MODY probability calculator should now be validated in other settings than where it was developed-and, as always, there is room for some improvements and modifications.

Current and Best Practices of Genetic Testing for Maturity Onset Diabetes of the Young: Views of Professional Experts

“…Such a risk profile has already been developed; the MODY calculator appears to discriminate well between MODY and type 1 and 2 diabetes and can be used to help select candidates for genetic testing for MODY. Further research is still needed to validate the model while implementing it in different settings and populations [13,32]. …”

Monogenic diabetes mellitus in Norway

“…We have registered more than 1500 suspected cases of monogenic diabetes and the number of patients who have received a genetic diagnosis is now approaching 500. In the future, we expect that more detailed phenotyping using radiological imaging and physiological characterization will improve the value of the registry, enabling us to diagnose monogenic diabetes more efficiently (32). An example is the use of ultrasound examination to diagnose HNF1B-MODY and CEL-MODY (13,33).…”

Maturity-Onset Diabetes of the Young

“…(14) Os familiares de primeiro grau têm uma probabilidade de 50% de adquirirem a mutação, conferindo-lhes um risco superior a 95% (penetrância elevada) de desenvolverem diabetes durante a sua vida ou, pelo menos, diminuição da tolerância à glicose ou anomalias da glicemia em jejum, até à sexta década de vida (3,7,15) . A distinção entre doentes com formas raras (14) , incluindo meios auxiliares de diagnóstico, até hoje ainda não utilizados na prática clínica para essa finalidade (18,19) . Esta revisão de literatura científica baseia-se numa leitura e estudo extensivo destes artigos, publicados até à data da realização desta revisão.…”