Precision therapy for three Chinese families with maturity-onset diabetes of the young (MODY12)

The Elusive Nature of ABCC8-related Maturity-Onset Diabetes of the Young (ABCC8-MODY). A Review of the Literature and Case Discussion

PURPOSE OF REVIEW

Maturity-onset diabetes of the young (MODY) are monogenic forms of diabetes resulting from genetic defects, usually transmitted in an autosomal dominant fashion, leading to β-cell dysfunction. Due to the lack of homogeneous clinical features and univocal diagnostic criteria, MODY is often misdiagnosed as type 1 or type 2 diabetes, hence its diagnosis relies mostly on genetic testing. Fourteen subtypes of MODY have been described to date. Here, we review ABCC8-MODY pathophysiology, genetic and clinical features, and current therapeutic options.

RECENT FINDINGS

ABCC8-MODY is caused by mutations in the adenosine triphosphate (ATP)-binding cassette transporter subfamily C member 8 (ABCC8) gene, involved in the regulation of insulin secretion. The complexity of ABCC8-MODY genetic picture is mirrored by a variety of clinical manifestations, encompassing a wide spectrum of disease severity. Such inconsistency of genotype-phenotype correlation has not been fully understood. A correct diagnosis is crucial for the choice of adequate treatment and outcome improvement. By targeting the defective gene product, sulfonylureas are the preferred medications in ABCC8-MODY, although efficacy vary substantially. We illustrate three case reports in whom a diagnosis of ABCC8-MODY was suspected after the identification of novel ABCC8 variants that turned out to be of unknown significance. We discuss that careful interpretation of genetic testing is needed even on the background of a suggestive clinical context. We highlight the need for further research to unravel ABCC8-MODY disease mechanisms, as well as to clarify the pathogenicity of identified ABCC8 variants and their influence on clinical presentation and response to therapy.

Diabetic Ketoacidosis in Patients with Maturity-Onset Diabetes of the Young

Maturity-onset diabetes of the young (MODY) is the most frequent monogenetic diabetes form. It is caused by mutations in genes important for the development and function of pancreatic beta-cells, resulting in impaired insulin secretion capacity. Up to now, 14 different types have been described. The inheritance pattern is autosomal dominant, leading to a strong family history with more than three affected generations. Young age at diagnosis and lack of pancreatic autoantibodies are further characteristics of MODY. The presence of diabetic ketoacidosis (DKA) was long regarded as an exclusion criterion for MODY. However, in recent years, several case reports on MODY patients presenting with DKA have been published. The present study aimed to give an overview of the current knowledge of DKA in MODY patients, with a collection of published case studies as a prerequisite for this review.

Adipose-Derived Stem Cell Exosomes Facilitate Diabetic Wound Healing: Mechanisms and Potential Applications

Wound healing in diabetic patients is frequently hampered. Adipose-derived stem cell exosomes (ADSC-eoxs), serving as a crucial mode of intercellular communication, exhibit promising therapeutic roles in facilitating wound healing. This review aims to comprehensively outline the molecular mechanisms through which ADSC-eoxs enhance diabetic wound healing. We emphasize the biologically active molecules released by these exosomes and their involvement in signaling pathways associated with inflammation modulation, cellular proliferation, vascular neogenesis, and other pertinent processes. Additionally, the clinical application prospects of the reported ADSC-eoxs are also deliberated. A thorough understanding of these molecular mechanisms and potential applications is anticipated to furnish a theoretical groundwork for combating diabetic wound healing.

Stem Cell-Derived Extracellular Vesicles: Promising Therapeutic Opportunities for Diabetic Wound Healing

Wound healing is a sophisticated and orderly process of cellular interactions in which the body restores tissue architecture and functionality following injury. Healing of chronic diabetic wounds is difficult due to impaired blood circulation, a reduced immune response, and disrupted cellular repair mechanisms, which are often associated with diabetes. Stem cell-derived extracellular vesicles (SC-EVs) hold the regenerative potential, encapsulating a diverse cargo of proteins, RNAs, and cytokines, presenting a safe, bioactivity, and less ethical issues than other treatments. SC-EVs orchestrate multiple regenerative processes by modulating cellular communication, increasing angiogenesis, and promoting the recruitment and differentiation of progenitor cells, thereby potentiating the reparative milieu for diabetic wound healing. Therefore, this review investigated the effects and mechanisms of EVs from various stem cells in diabetic wound healing, as well as their limitations and challenges. Continued exploration of SC-EVs has the potential to revolutionize diabetic wound care.

Identification and precision therapy for three maturity-onset diabetes of the young (MODY) families caused by mutations in the HNF4A gene

Background

Heterozygous pathogenic variants in HNF4A gene cause maturity-onset diabetes of the young type 1 (MODY1). The mutation carriers for MODY1 have been reported to be relatively rare, in contrast to the most frequently reported forms of MODY2 and MODY3.

Methods

Whole exome sequencing (WES) and Sanger sequencing were performed for genetic analysis of MODY pedigrees. Tertiary structures of the mutated proteins were predicted using PyMOL software.

Results

Three heterozygous missense mutations in the HNF4A gene, I159T, W179C, and D260N, were identified in the probands of three unrelated MODY families using WES, one of which (W179C) was novel. Cascade genetic screening revealed that the mutations co-segregated with hyperglycemic phenotypes in their families. The molecular diagnosis of MODY1 has partly transformed its management in clinical practice and improved glycemic control. The proband in family A successfully converted to sulfonylureas and achieved good glycemic control. Proband B responded well to metformin combined with diet therapy because of his higher body mass index (BMI). The proband in family C, with paternal-derived mutations, had markedly defective pancreatic β-cell function due to the superposition effect of T2DM susceptibility genes from the maternal grandfather, and he is currently treated with insulin. In silico analysis using PyMOL showed that the I159T and D260N mutations altered polar interactions with the surrounding residues, and W179C resulted in a smaller side chain.

Discussion

We identified three heterozygous missense mutations of HNF4A from Chinese MODY families. Structural alterations in these mutations may lead to defects in protein function, further contributing to the hyperglycemic phenotype of mutation carriers.