Neonatal Diabetes due to a Mutation in the Distal PTF1A Enhancer: A Case Report and Literature Review

: Biallelic variants in the pancreas-specific transcription factor 1A (PTF1A) gene are a rare cause of permanent neonatal diabetes. We report a case of neonatal diabetes with unique clinical manifestations. The clinical diagnosis of the affected infant was confirmed by insufficient endocrine and exocrine pancreas activity; however, the pancreas was normal in imaging. Molecular analyses identified a novel homozygous single nucleotide variant (Chr10, g.23508441T > G), affecting a highly conserved nucleotide within a distal enhancer of the PTF1A gene. The literature review showed that most of these patients had IUGR and imaging evidence of pancreatic agenesis or hypoplasia. We suggest that pancreatic imaging and evaluation of exocrine pancreas function can help early confirmation of the diagnosis in patients with permanent neonatal diabetes.

Primate-specific ZNF808 is essential for pancreatic development in humans

Identifying genes linked to extreme phenotypes in humans has the potential to highlight new biological processes fundamental for human development. Here we report the identification of homozygous loss of function variants in the primate-specific gene ZNF808 as a cause of pancreatic agenesis. ZNF808 is a member of the KRAB zinc finger protein (KZFPs) family, a large and rapidly evolving group of epigenetic silencers that target transposable elements. Loss of ZNF808 in vitro results in aberrant activation of many transposable elements it normally represses during early pancreas development. We show that this results in inappropriate specification of cell fate with induction of genes associated with liver endoderm and a loss of pancreatic identity. This suggests that ZNF808 and its transposable element targets play a critical role in cell fate specification during human pancreatic development. This is the first report of loss of a primate-specific gene causing a congenital developmental disease and highlights the essential role of ZNF808 for pancreatic development in humans.

Using Human Induced Pluripotent Stem Cell Derived Organoids to Identify New Pathologies in Patients with PDX1 Mutations

Two patients with mutations in PDX1 presented with pancreatic agenesis, chronic diarrhea and poor weight gain, the causes of which were not identified through routine clinical testing. We generated patient derived organoids as a novel diagnostic strategy and observed that PDX1188delC/188delC antral organoids convert to an intestinal phenotype, while intestinal organoids undergo gastric metaplasia with significant reduction in enteroendocrine cells. This prompted a re-examination of gastric and intestinal biopsies from both PDX1188delC/188delC patients, which recapitulated organoid phenotypes. Antral biopsies had increased parietal cells and lacked G-cells suggesting loss of antral identity. These patients will now be monitored for the progression of metaplasia. This study demonstrates the utility of organoids for patient diagnoses and treatment.

Genes predisposing to neonatal diabetes mellitus and pathophysiology: Current findings

BACKGROUND: Precision medicine, described as a therapeutic procedure in which complex diseases are treated based on the causal gene and pathophysiology, is being considered for diabetes mellitus (DM). To this end, several monogenetic mutations in the beta cells have been linked with neonatal diabetes mellitus (NDM), however, the list of suspect genes is expansive, necessitating an update. This study, therefore, provides an update on NDM candidate genes and pathophysiology. RESULTS: Reputable online academic databases were searched for relevant information, which led to the identification of 43 genes whose mutations are linked to the condition. Of the linked genes, mutations in the KCNJ11, ABCC8, and INS genes as well as the genes on 6q24 chromosomal region are the most frequently implicated. Mutations in these genes can cause pancreatic agenesis and developmental errors, resulting in NDM in the first six to twelve months of birth. The clinical presentations of NDM include frequent urination, rapid breathing, and dehydration, among others. CONCLUSIONS: Monogenetic mutations in the beta cells may cause NDM with distinct pathophysiology from other DM. Treatment options that target NDM candidate genes and pathophysiology may lead to an improved treatment compared with the present generalized treatment for all forms of DM.

Genetically engineered pigs manifesting pancreatic agenesis with severe diabetes

IntroductionPancreatic duodenum homeobox 1 (Pdx1) expression is crucial for pancreatic organogenesis and is a key regulator of insulin gene expression. Hairy and enhancer of split 1 (Hes1) controls tissue morphogenesis by maintaining undifferentiated cells. Hes1 encodes a basic helix loop helix (bHLH) transcriptional repressor and functionally antagonizes positive bHLH genes, such as the endocrine determination gene neurogenin-3. Here, we generated a new pig model for diabetes by genetic engineering Pdx1 and Hes1 genes.Research design and methodsA transgenic (Tg) chimera pig with germ cells carrying a construct expressing Hes1 under the control of the Pdx1 promoter was used to mate with wild-type gilts to obtain Tg piglets.ResultsThe Tg pigs showed perinatal death; however, this phenotype could be rescued by insulin treatment. The duodenal and splenic lobes of the Tg pigs were slender and did not fully develop, whereas the connective lobe was absent. β cells were not detected, even in the adult pancreas, although other endocrine cells were detected, and exocrine cells functioned normally. The pigs showed no irregularities in any organs, except diabetes-associated pathological alterations, such as retinopathy and renal damage.ConclusionPdx1-Hes1 Tg pigs were an attractive model for the analysis of pancreatic development and testing of novel treatment strategies for diabetes.

A NONSENSE GATA6 MUTATION EXPLAINS HISTORY OF CONGENITAL HEART DEFECTS AND 10 YEARS OF POORLY-CONTROLLED DIABETES LACKING DKA IN A NON-OBESE 30 YEAR-OLD INCIDENTALLY FOUND TO HAVE PANCREATIC HYPOPLASIA

Objective: To report a case of diabetes mellitus (DM) associated with partial pancreatic agenesis and congenital heart disease (CHD) in a patient found to have a nonsense mutation of the GATA6 gene. Methods: We present the imaging, laboratory, and genetic findings, and describe the clinical course of a patient with an atypical presentation of DM as well as CHD, who was found to have partial pancreatic agenesis on computed tomography (CT) imaging. Genetic testing was performed to identify monogenic DM. Results: A 30-year-old nonobese female with a waxing and waning pattern of insulin-dependent DM diagnosed at the age of 20 was found to have partial pancreatic agenesis on CT scan. It was unclear whether the patient was experiencing undetected hyperglycemia prior to initial diagnosis of DM. She had no history of diabetic ketoacidosis (DKA) despite poorly-controlled diabetes and years without insulin treatment. The patient also had congenital tricuspid atresia, ventricular septal defect, and transposition of the great vessels with surgical correction in childhood. Partial pancreatic agenesis and CHD with atypical DM prompted genetic testing for monogenic DM, and a nonsense mutation of the GATA6 (c.1242C>A, p.C414*) gene was found. Conclusion: GATA6 mutations are associated with a broad spectrum of diabetic phenotypes, pancreatic agenesis, and a variety of CHDs. This case highlights the importance of considering monogenic diabetes in young, nonobese patients with diabetes, particularly with negative pancreatic antibodies and no history of DKA. Further, this case demonstrates the importance of testing for GATA6 mutations in any young patient with diabetes and CHD.