A De Novo Whole GCK Gene Deletion Not Detected by Gene Sequencing, in a Boy with Phenotypic GCK Insufficiency

Abstract EN

We report on a boy with diabetes mellitus and a phenotype indicating glucokinase (GCK) insufficiency, but a normal GCK gene examination applying direct gene sequencing.

The boy was referred for diabetes mellitus at 7.5 years old.

His father, grandfather and great grandfather suffered type 2 DM.

Several blood glucose profiles showed (BG) of 6.5–10 mmol/L L.

After three years on neutral insulin Hagedorn (NPH) in a dose of 0.3 IU/kg/day haemoglobin A1c (HbA1c) was 6.8%.

Treatment was changed to sulphonylurea 750 mg a day, and after 4 years HbA1c was 7%.

At that time a multiplex ligation-dependent amplification gene dosage assay (MLPA) was done, revealing a whole GCK gene deletion.

Medical treatment was ceased, and after one year HbA1c was 6.8%.

This case underscores the importance of a MLPA examination if the phenotype of a patient is strongly indicative of GCK insufficiency and no mutation is identified using direct sequencing.