Marked intrafamilial variability of exocrine and endocrine pancreatic phenotypes due to a splice site mutation in GATA6

The objective of this study was to describe the clinical characteristics of syndromic neonatal diabetes in a family with a GATA6 mutation. A girl, currently aged 12 years 3 months, was born with intrauterine growth retardation: weight 1600g (-4.3 SDS) at term. After birth, foramen ovale and patent ductus arteriosus (PDA) were diagnosed by echocardiography. Diabetes was diagnosed on the 9th day after birth. Exocrine pancreatic insufficiency was clinically diagnosed at about 2 years of age and pancreatic agenesis was revealed later by magnetic resonance imaging. Her father had undergone surgery during infancy for PDA and had developed insulin dependent diabetes at 12 years of age. Ultrasound revealed a thin pancreas with normal length and anatomical structure. He has subclinical exocrine pancreatic insufficiency, low insulin needs and no late complications of diabetes up to the age of 40 years. Sequencing of GATA6 identified a heterozygous splicing mutation, 1136-2A>G, in the girl and her father. Testing of the paternal grandparents showed that the mutation was likely to have arisen de novo in the father. Identification of a GATA6 mutation explains the cardiac anomalies and diabetes in this family. This case highlights the marked intra-familial variability of both exocrine and endocrine pancreatic phenotypes in patients with GATA6 mutations.