P. Dussoix et al., DIAGNOSTIC HETEROGENEITY OF DIABETES IN LEAN YOUNG-ADULTS - CLASSIFICATION BASED ON IMMUNOLOGICAL AND GENETIC-PARAMETERS, Diabetes, 46(4), 1997, pp. 622-631
The aim of our study was to investigate the relative prevalence of the
different forms of diabetes in young adults and their respective clin
ical characteristics. Included were 51 nonobese patients (BMI < 27 kg/
m(2)) with diabetes diagnosed before age 40, excluding typical IDDM. E
ach patient was subjected to screening for glucokinase gene (MODY2) an
d mitochondrial DNA (at nucleotide 3243) mutations, to HLA class II ge
notyping, and screening for the presence of islet cell antibodies (ICA
s) and anti-GAD antibodies. Informative families were analyzed for lin
kage of diabetes to chromosome 12q (MODY3). Based on clinical criteria
, patients were subdivided into MODY (n = 19) and non-MODY (n 32). In
the MODY group, we identified three patients with MODY2, one with the
3243 mitochondrial mutation, and another with autoimmune diabetes. One
of the five MODY families available for Linkage study was shown to ha
ve MODY3. In the non-MODY group, we found five patients with autoimmun
e diabetes and one with MODY2. No clinical parameter was helpful to cl
assify patients in one of these subclasses of diabetes; however the gl
ucagon-stimulated C-peptide was useful to discriminate between MODY2 p
atients and the others. In conclusion, young and lean non-insulin-depe
ndent diabetic patients constitute a very heterogeneous group, althoug
h they present similar clinical characteristics. The clinical distinct
ion of MODY and non-MODY patients allows correct classification in, at
most, 75% of the patients and thus is not sufficient to predict clini
cal course. However, immunological and genetic parameters allowed us t
o classify only 25% of the patients in specific diagnostic classes.