Endocrine Abstracts

Transient neonatal diabetes mellitus (TNDM) occurs in 50-60% of all cases of neonatal diabetes mellitus (NDM). The most common cause of TNDM (70%) is almost invariably associated with defect in chromosome 6 and mutations in the KCNJ11, ABCC8, INS, NHF1B etc. genes. TNDM is caused by mutations in the GATA6 gene in rare cases. This gene encodes a transcription factor that is important for the development of the hematopoietic, cardiac and gastrointestinal systems.

Clinical Case: Proband is a female born at 35 week of gestation with intrauterine growth retardation (weight 1580 g (SDS -2.29), length 40 cm (SDS -2.65)) via cesarean section. The proband was fedded using tube feeding in neonatal period. The proband was diagnosed with hyperglycemia 29.6 mmol/l in the neonatal period, insulin therapy was started. Insulin was stopped in 1 month of life. Normoglycemia was observed. Family history of diabetes was negative. The proband was relapse of diabetes in 3 years old after a respiratory infection. She had polyuria, polydipsia and weight loss. HbA1c 11.5%, glycemia 18.6 mmol/l. Insulin (As part, 0.4 U/kg/day) was started. Fasting C-peptide 0.69 ng/ml, stimulated C-peptide in 120 min - 2.32 ng/ml. Specific islet antibodies (GADA, IA2A, IAA, ZnT8A) were negative. Pancreatic hypoplasia was diagnosed due to ultrasound. Genetic test (NGS 27 genes) was performed, no mutations were detected. Proband had extrapancreatic features: moderate growth retardation (growth SDS -1.95), patent ductus arteriosus, mitral valve prolapse, gallbladder agenesis, umbilical hernia, autoimmune thyroiditis. At the age of 8 years (diabetes duration was 5 years) patient was treated fast acting insulin Aspart, 0.7 U/kg/day. HbA1c 5.2%, fasting C-peptide 0.71 ng/ml, stimulated C-peptide in 120 min – 0.9 ng/ml. Whole-exome sequencing revealed novel pathogenic heterozygous mutation c.1302+4 1302+7del in exon 3 of the GATA6 gene, leading to a deletion of 4 nucleotides.

Conclusion: TNDM is rarely caused by mutations in the GATA6 gene. The development of NDM due to mutations in the GATA6 gene is probably associated with pancreatic hypoplasia. Diabetes associated with mutations in the GATA6 gene is progressive. Patients with mutations in the GATA6 gene have extrapancreatic features (congenital heart defects, gallbladder agenesis, umbilical hernia).