STUDY OF KCNJ11 GENE MUTATIONS IN ASSOCIATION WITH MONOGENIC DIABETES OF INFANCY AND RESPONSE TO SULFONYLUREA TREATMENT IN A COHORT STUDY IN EGYPT

Investigation of Monogenic Diabetes Genes in Thai Children with Autoantibody Negative Diabetes Requiring Insulin

Purpose

The objective of this study was to clarify the phenotypic characteristics of monogenic diabetes abnormalities in Thai children with autoantibody-negative insulin.

Patients and Methods

Two hundred and thirty-one Thai type 1 diabetes (T1D) patients out of 300 participants with recent-onset diabetes were analyzed for GAD65 and IA2 pancreatic autoantibodies. A total of 30 individuals with T1D patients with negative autoantibody were screened for 32 monogenic diabetes genes by whole-exome sequencing (WES).

Results

All participants were ten men and twenty women. The median age to onset of diabetes was 8 years and 3 months. A total of 20 people with monogenic diabetes carried genes related to monogenic diabetes. The PAX4 (rs2233580) in ten patients with monogenic diabetes was found. Seven variants of WFS1 (Val412Ala, Glu737Lys, Gly576Ser, Cys673Tyr, Arg456His, Lys424Glu, and Gly736fs) were investigated in patients in this study. Furthermore, the pathogenic variant, rs115099192 (Pro407Gln) in the GATA4 gene was found. Most patients who carried PAX4 (c.575G>A, rs2233580) did not have a history of DKA. The pathogenic variant GATA4 variant (c.1220C>A, rs115099192) was found in a patient with a history of DKA.

Conclusion

This study demonstrated significant genetic overlap between autoantibody-negative diabetes and monogenic diabetes using WES. All candidate variants were considered disease risk with clinically significant variants. WES screening was the first implemented to diagnose monogenic diabetes in Thai children, and fourteen novel variants were identified in this study and need to be investigated in the future.

Early-onset diabetes in Africa: A mini-review of the current genetic profile

Early-onset diabetes is poorly diagnosed partly due to its heterogeneity and variable presentations. Although several genes have been associated with the disease, these genes are not well studied in Africa. We sought to identify the major neonatal, early childhood, juvenile, or early-onset diabetes genes in Africa; and evaluate the available molecular methods used for investigating these gene variants. A literature search was conducted on PubMed, Scopus, Africa-Wide Information, and Web of Science databases. The retrieved records were screened and analyzed to identify genetic variants associated with early-onset diabetes. Although 319 records were retrieved, 32 were considered for the current review. Most of these records (22/32) were from North Africa. The disease condition was genetically heterogenous with most cases possessing unique gene variants. We identified 22 genes associated with early-onset diabetes, 9 of which had variants (n = 19) classified as pathogenic or likely pathogenic (PLP). Among the PLP variants, IER3IP1: p.(Leu78Pro) was the variant with the highest number of cases. There was limited data from West Africa, hence the contribution of genetic variability to early-onset diabetes in Africa could not be comprehensively evaluated. It is worth mentioning that most studies were focused on natural products as antidiabetics and only a few studies reported on the genetics of the disease. ABCC8 and KCNJ11 were implicated as major contributors to early-onset diabetes gene networks. Gene ontology analysis of the network associated ion channels, impaired glucose tolerance, and decreased insulin secretions to the disease. Our review highlights 9 genes from which PLP variants have been identified and can be considered for the development of an African diagnostic panel. There is a gap in early-onset diabetes genetic research from sub-Saharan Africa which is much needed to develop a comprehensive, efficient, and cost-effective genetic panel that will be useful in clinical practice on the continent and among the African diasporas.

Genetic and Epigenetic Factors in Gestational Diabetes Mellitus Pathology

Gestational diabetes (GDM) is the carbohydrate intolerance occurring during pregnancy. The risk factors of GDM include obesity, advanced maternal age, polycystic ovary syndrome, multigravidity, a sedentary lifestyle, and pre-existing hypertension. Additionally, complex genetic and epigenetic processes are also believed to play a crucial role in the development of GDM. In this narrative review, we discuss the role of genetic and epigenetic factors in gestational diabetes mellitus pathogenesis.

Do second generation sequencing techniques identify documented genetic markers for neonatal diabetes mellitus?

Neonatal diabetes mellitus (NDM) is noted as a genetic, heterogeneous, and rare disease in infants. NDM occurs due to a single-gene mutation in neonates. A common source for developing NDM in an infant is the existence of mutations/variants in the KCNJ11 and ABCC8 genes, encoding the subunits of the voltage-dependent potassium channel. Both KCNJ11 and ABCC8 genes are useful in diagnosing monogenic diabetes during infancy. Genetic analysis was previously performed using first-generation sequencing techniques, such as DNA-Sanger sequencing, which uses chain-terminating inhibitors. Sanger sequencing has certain limitations; it can screen a limited region of exons in one gene, but it cannot screen large regions of the human genome. In the last decade, first generation sequencing techniques have been replaced with second-generation sequencing techniques, such as next-generation sequencing (NGS), which sequences nucleic-acids more rapidly and economically than Sanger sequencing. NGS applications are involved in whole exome sequencing (WES), whole genome sequencing (WGS), and targeted gene panels. WES characterizes a substantial breakthrough in human genetics. Genetic testing for custom genes allows the screening of the complete gene, including introns and exons. The aim of this review was to confirm if the 22 genetic variations previously documented to cause NDM by Sanger sequencing could be detected using second generation sequencing techniques. The author has cross-checked global studies performed in NDM using NGS, ES/WES, WGS, and targeted gene panels as second-generation sequencing techniques; WES confirmed the similar variants, which have been previously documented with Sanger sequencing. WES is documented as a powerful tool and WGS as the most comprehensive test for verified the documented variants, as well as novel enhancers. This review recommends for the future studies should be performed with second generation sequencing techniques to identify the verified 22 genetic and novel variants by screening in NDM (PNDM or TNMD) children.