Clinical characteristics and long-term follow-up of patients with diabetes due to PTF1A enhancer mutations

Abstract

Context: Biallelic mutations in the PTF1A enhancer are the commonest cause of isolated pancreatic agenesis. These patients do not have severe neurological features associated with loss-of-function PTF1A mutations. Their clinical phenotype and disease progression have not been well characterised. Objective: To evaluate phenotype and genotype characteristics and long-term follow78 up of patients with PTF1A enhancer mutations. Setting: Twelve tertiary paediatric endocrine referral centres. Patients: 30 patients with diabetes caused by PTF1A enhancer mutations. Median follow-up duration was 4 years. Main Outcome Measures: Presenting and follow-up clinical (birthweight, gestational age, symptoms, auxology) and biochemical (pancreatic endocrine and exocrine functions, liver function, glycated haemoglobin) characteristics, pancreas imaging, genetic analysis. Results: Five different homozygous mutations affecting conserved nucleotides in the PTF1A distal enhancer were identified. The commonest was the Chr10:g.23508437A>G mutation (n=18). Two patients were homozygous for the novel Chr10:g.23508336A>G mutation. Birthweight was often low (median SDS=-3.4). The majority of patients presented with diabetes soon after birth (median age of diagnosis:5 days). Only 2/30 presented after 6 months of age. All patients had exocrine pancreatic insufficiency. Five had developmental delay (4 mild) on long term follow-up. Previously undescribed common features in our cohort were: transiently elevated ferritin level (n=12/12 tested), anaemia (19/25) and cholestasis (14/24). Postnatal growth was impaired (median height SDS:- 2.35, median BMI SDS:-0.52 SDS) with 20/29 (69%) cases having growth retardation. Conclusion: We report the largest series of patients with diabetes caused by PTF1A enhancer mutations. Our results expand the disease phenotype, identifying recurrent extra-pancreatic features which likely reflect long-term intestinal malabsorption.