Clinical and genetic characterization and long-term evaluation of individuals with maturity-onset diabetes of the young (MODY): The journey towards appropriate treatment

MODY calculator applied in patients with clinical diagnosis of type 1 diabetes mellitus: Is a higher cutoff needed?

Aim

This study aimed to evaluate the mean post-test probability (PTP) of the Maturity-onset diabetes of the young (MODY) calculator in a multiethnic cohort of patients previously diagnosed with type 1 diabetes (T1DM).

Materials and methods

The MODY probability calculator proposed by Shields and colleagues (2012) was applied to 117 patients from a T1DM outpatient clinic at a tertiary hospital in Brazil. Additionally, two exons of the HNF1A gene were sequenced in eight patients who hadn't received insulin treatment within six months after the diagnosis.

Results

17.1 % of patients achieved PTP >10 %; 11.1 % achieved PTP >25 % (and all patients >30 %), and 7.7 % achieved PTP >40 %. Among the patients who were selected for genetic sequencing, 100 % presented PTP >30 %, with 66.6 % achieving PTP >40 % and 41.6 % achieving PTP >75 %. These cutoffs are as suggested for the Brazilian population, according to previous investigations. No mutation was observed in the sequenced exons.

Conclusion

Considering that only around 10 % of the evaluated cases achieved PTP >30 %, it is highly probable that the most suitable cutoff to select patients for genetic sequencing in a Brazilian cohort of T1DM is higher than the cutoff used in Caucasian populations.

A case series of maturity-onset diabetes of the young highlighting atypical presentations and the implications of genetic diagnosis

Maturity-onset diabetes of the young (MODY) is a clinically heterogeneous group of monogenic diabetes characterized by onset at a young age and an autosomal dominant mode of inheritance. Notably, MODY accounts for 2%-5% of all diabetes cases, and its distinction from types 1 (T1DM) and 2 (T2DM) diabetes mellitus is often challenging. We report herein the cases of two girls and a boy who presented initially with diabetic ketoacidosis. In view of the strong family history of diabetes in all three of them, the diagnosis of MODY was considered and confirmed by molecular testing. The patient in Case 1 (a 10-year-old girl) had a variation in the HNF1A gene (MODY 3). The patient in Case 2 (a 13-year-old girl) had a variation in the HNF1B gene (MODY 5) and was also clinically diagnosed with HNF1B MODY due to short stature, abnormal renal function, renal cysts, unicornuate uterus, and diabetic ketoacidosis at presentation. The patient in Case 3 (a 14-year-old boy) had a variation in the KCNJ11 gene (MODY 13) and presented with diabetic ketoacidosis; after initially being treated as having T1DM, he developed progressive weight gain, acanthosis nigricans, and decreased requirement of insulin. The patients in Cases 1 and 3 were subsequently treated with oral sulfonylureas and insulin was gradually tapered and interrupted, resulting in drastic improvement in glucose control. The patient in Case 2 remained on insulin, as this is the appropriate management for MODY 5. This case series demonstrates that atypical cases of MODY with ketoacidosis do occur, underscoring the potential for this complication within the phenotypic spectrum of MODY. In patients with atypical presentations, a thorough family history taking may reveal the diagnosis of MODY.

The performance of the MODY calculator in a non-Caucasian, mixed-race population diagnosed with diabetes mellitus before 35 years of age

BACKGROUND

A maturity-onset diabetes of the young (MODY) calculator has been described and validated for use in European Caucasians. This study evaluated its performance in Brazilians diagnosed with diabetes mellitus (DM) before 35 years of age.

METHODS

The electronic records of 391 individuals were reviewed in 2020 at the diabetes clinic of a quaternary hospital in São Paulo were analyzed: 231 with type 1 DM (T1DM), 46 with type 2 (T2DM) and 114 with MODY. The MODY calculator was applied to the three groups. A receiver operating characteristic curve was calculated to obtain cut-off points for this population.

RESULTS

The principal differences between the MODY and the T1DM and T2DM groups were body mass index, a positive family history of diabetes and mean HbA1c level. Age at diagnosis in the MODY group was only significantly different compared to the T2DM group. Specificity and sensitivity were good for the cut-off points of 40%, 50% and 60%, with the accuracy of the model for any of these cut-off points being > 95%.

CONCLUSION

The capacity of the calculator to identify Brazilian patients with MODY was good. Values ≥ 60% proved useful for selecting candidates for MODY genetic testing, with good sensitivity and specificity.