A new variant in the GATA6 gene associated with tracheoesophageal fistula, pulmonary vein stenosis and neonatal diabetes.

INTRODUCTION: GATA6 is a gene that encodes a transcription factor with a key role in the development of several organ systems, including the development of the pancreas. It is associated with neonatal diabetes but also with other extra-pancreatic anomalies. CASE PRESENTATION: This report describes the association of tracheoesophageal fistula (TEF), pulmonary vein stenosis (PVS), and neonatal diabetes caused by a novel mutation of the GATA6 gene in a small-for-gestational-age male neonate born at 32 weeks of gestation. Next-Generation Sequencing revealed the novel heterozygous variant c.1502C>G in the GATA6 gene, which determines the introduction of the premature stop codon p.Ser501Ter at the protein level. This de novo nonsense variant was not detected in the analyzed parental DNA samples and has not been previously described in the literature. At about two months of life, a PVS was suspected. The PVS progressively increased with the development of an intramural component, resulting in severe postcapillary pulmonary hypertension. The child died at about 4 months of life. CONCLUSION: TEF can be associated with GATA6 variants. In the case of neonatal diabetes and TEF, neonatologists should be aware of this association and should also investigate the child for complex congenital heart disorders, such as in our case, with a cardiac computed tomography.

The changing landscape of neonatal diabetes mellitus in Italy between 2003-2022.

CONTEXT: In the last decade Sanger method of DNA sequencing has been replaced by next generation sequencing (NGS). NGS is valuable in conditions characterized by high genetic heterogeneity such as neonatal diabetes mellitus (NDM). OBJECTIVE: To compare results of genetic analysis of patients with NDM and congenital severe insulin resistance (c.SIR) identified in Italy in 2003-2012 (Sanger) versus 2013-2022 (NGS). METHODS: We reviewed clinical and genetic records of 104 cases with diabetes onset before 6 months of age (NDM+c.SIR) of the Italian dataset. RESULTS: Fiftyfive patients (50 NDM + 5 c.SIR) were identified during 2003-2012 and 49 (46 NDM + 3 c.SIR) in 2013-2022. Twenty-year incidence was 1:103,340 (NDM) and 1:1,240,082 (c.SIR) live births. Frequent NDM/c.SIR genetic defects (KCNJ11, INS, ABCC8, 6q24, INSR) were detected in 41 and 34 probands during 2003-2012 and 2013-2022, respectively. We identified a pathogenic variant in rare genes in a single proband (GATA4) (1/42 or 2.4%) during 2003-2012 and in 8 infants (RFX6, PDX1, GATA6, HNF1B, FOXP3, IL2RA, LRBA, BSCL2) during 2013-2022 (8/42 or 19%, p= 0.034 vs 2003-2012). Notably, five among rare genes were recessive. Swift and accurate genetic diagnosis led to appropriate treatment: patients with autoimmune NDM (FOXP3, IL2RA, LRBA), were subjected to bone marrow transplant; patients with pancreas agenesis/hypoplasia (RFX6, PDX1) were supplemented with pancreatic enzymes and the individual with lipodystrophy caused by BSCL2 was started on metreleptin. CONCLUSIONS: NGS substantially improved diagnosis and precision therapy of monogenic forms of neonatal diabetes and congenital SIR in Italy.

Monogenic diabetes clinic (MDC): 3-year experience.

AIM: In the pediatric diabetes clinic, patients with type 1 diabetes mellitus (T1D) account for more than 90% of cases, while monogenic forms represent about 6%. Many monogenic diabetes subtypes may respond to therapies other than insulin and have chronic diabetes complication prognosis that is different from T1D. With the aim of providing a better diagnostic pipeline and a tailored care for patients with monogenic diabetes, we set up a monogenic diabetes clinic (MDC). METHODS: In the first 3 years of activity 97 patients with non-autoimmune forms of hyperglycemia were referred to MDC. Genetic testing was requested for 80 patients and 68 genetic reports were available for review. RESULTS: In 58 subjects hyperglycemia was discovered beyond 1 year of age (Group 1) and in 10 before 1 year of age (Group 2). Genetic variants considered causative of hyperglycemia were identified in 25 and 6 patients of Group 1 and 2, respectively, with a pick up rate of 43.1% (25/58) for Group 1 and 60% (6/10) for Group 2 (global pick-up rate: 45.5%; 31/68). When we considered probands of Group 1 with a parental history of hyperglycemia, 58.3% (21/36) had a positive genetic test for GCK or HNF1A genes, while pick-up rate was 18.1% (4/22) in patients with mute family history for diabetes. Specific treatments for each condition were administered in most cases. CONCLUSION: We conclude that MDC may contribute to provide a better diabetes care in the pediatric setting.

Mutations in B9D1 and MKS1 cause mild Joubert syndrome: expanding the genetic overlap with the lethal ciliopathy Meckel syndrome.

Joubert syndrome is a clinically and genetically heterogeneous ciliopathy characterized by a typical cerebellar and brainstem malformation (the "molar tooth sign"), and variable multiorgan involvement. To date, 24 genes have been found mutated in Joubert syndrome, of which 13 also cause Meckel syndrome, a lethal ciliopathy with kidney, liver and skeletal involvement. Here we describe four patients with mild Joubert phenotypes who carry pathogenic mutations in either MKS1 or B9D1, two genes previously implicated only in Meckel syndrome.