Clinical feature: 

Definition: MODY1 is an autosomal dominant early-onset type 2 diabetes caused by mutations of the HNF4A gene.

Pathogenesis: This gene is in the same signaling cascade as TCF1, the gene where defects are responsible for MODY3. Therefore the pathogenesis and clinical expression are similar.

Epidemiology: There are only some few cases reported throughout the word.

Diagnostics: 

Differential: All know types of MODY diabetes are characterized by autosomal dominant inheritance, primary non-insulin-dependence, and manifestation in young age (mostly before 25 years of age)  » » » 
   The clinical course of MODY2 diabetes varies in that it remains non-insulin-dependent.  » » » 

Strategy: The diagnostic procedures generally are the same for all types of MODY diabetes.

Literature: 

Fajans SS et al. (2001) Molecular mechanisms and clinical pathophysiology of maturity-onset diabetes of the young.
Weng J et al. (2002) Screening for MODY mutations, GAD antibodies, and type 1 diabetes--associated HLA genotypes in women with gestational diabetes mellitus.