Mutations in glucokinase and other genes detected in neonatal and type 1B diabetes patient using whole exome sequencing may lead to disease-causing changes in protein activity

The use of fibroblasts as a valuable strategy for studying mitochondrial impairment in neurological disorders

Neurological disorders (NDs) are characterized by progressive neuronal dysfunction leading to synaptic failure, cognitive impairment, and motor injury. Among these diseases, Alzheimer's disease (AD), Parkinson's disease (PD), Huntington’s disease (HD), and amyotrophic lateral sclerosis (ALS) have raised a significant research interest. These disorders present common neuropathological signs, including neuronal dysfunction, protein accumulation, oxidative damage, and mitochondrial abnormalities. In this context, mitochondrial impairment is characterized by a deficiency in ATP production, excessive production of reactive oxygen species, calcium dysregulation, mitochondrial transport failure, and mitochondrial dynamics deficiencies. These defects in mitochondrial health could compromise the synaptic process, leading to early cognitive dysfunction observed in these NDs. Interestingly, skin fibroblasts from AD, PD, HD, and ALS patients have been suggested as a useful strategy to investigate and detect early mitochondrial abnormalities in these NDs. In this context, fibroblasts are considered a viable model for studying neurodegenerative changes due to their metabolic and biochemical relationships with neurons. Also, studies of our group and others have shown impairment of mitochondrial bioenergetics in fibroblasts from patients diagnosed with sporadic and genetic forms of AD, PD, HD, and ALS. Interestingly, these mitochondrial abnormalities have been observed in the brain tissues of patients suffering from the same pathologies. Therefore, fibroblasts represent a novel strategy to study the genesis and progression of mitochondrial dysfunction in AD, PD, HD, and ALS. This review discusses recent evidence that proposes fibroblasts as a potential target to study mitochondrial bioenergetics impairment in neurological disorders and consequently to search for new biomarkers of neurodegeneration.

Childhood-onset mild diabetes caused by a homozygous novel variant in the glucokinase gene

PURPOSE

Heterozygous loss-of-function mutations in the glucokinase (GCK) gene cause MODY 2, which is characterized by asymptomatic fasting hyperglycemia and does not require insulin treatment. Conversely, homozygous loss-of-function mutations in the same gene give rise to permanent neonatal diabetes mellitus (DM) that appears in the first 6-9 months of life and necessitates lifelong insulin treatment. We aimed to present the genotypic and phenotypic features of a 13-year-old patient diagnosed with DM at the age of 3 years due to a homozygous variant in the GCK gene.

METHODS

The patient's clinical and laboratory findings at follow-up were not consistent with the initial diagnosis of type 1 DM; thus, next-generation sequencing of MODY genes (GCK, HNF1A, HNF1B, and HNF4A genes) was performed to identify monogenic causes of DM.

RESULTS

A novel homozygous variant c.1222 G > T in the GCK gene was revealed. In silico analysis identified it as a pathogenic variant. His mother, father, and brother had the same heterozygous variant in the GCK gene and were diagnosed with MODY 2 (mild fasting hyperglycemia and elevated HbA1c) after genetic counseling.

CONCLUSION

In this case report, a patient with a homozygous variant in the GCK gene, who was diagnosed with DM after the infantile period, was presented, highlighting the fact that cases with homozygous variants in the GCK gene can, though rarely, present at a later age with a milder phenotype.

Momordica cymbalaria improves reproductive parameters in alloxan-induced male diabetic rats

Male reproductive dysfunction is one of the common complications of diabetes mellitus that causes infertility. This study was designed to investigate the protective effect of Momordica cymbalaria (M. cymbalaria) extracts on diabetes mediated reproductive toxicity in male Wistar rats. The induction of diabetes was performed using a single intraperitoneal injection of alloxan (120 mg/kg). Skin and seed extracts (250 and 500 mg/kg) of M. cymbalaria were orally administered to alloxan-induced diabetic male rats for 28 days. Postprandial blood glucose (PBG) levels were recorded at 7-day interval for four weeks. The effects of the treatment on blood glucose, weight of reproductive organs, sperm count, testosterone levels, antioxidant capacity, and histomorphology were evaluated. Treatment with the above extracts of M. cymbalaria significantly (p < 0.05) improved the reproductive parameters as well as the antioxidant levels superoxide dismutase (SOD) and glutathione-s-transferase (GST) in the diabetic rats. Also, oral treatment with M. cymbalaria extracts significantly reduced the PBG and malondialdehyde (MDA) levels. Further, it revived the histomorphology of reproductive organs in diabetic rats. Interestingly, skin extract at a dose of 500 mg/kg was found to be more efficient in elevating the level of testosterone and sperm count in the diabetic rats. Based on the results, it is clear that M. cymbalaria not only regulates the postprandial blood glucose levels but also improves the reproductive health in the diabetic state.

Genetic Spectrum of Neonatal Diabetes

Neonatal diabetes (ND) appears during the first months of life and is caused by a single gene mutation. It is heterogenous and very different compared to other forms of multi-factorial or polygenic diabetes. Clinically, this form is extremely severe, however, early genetic diagnosis is pivotal for successful therapy. A large palette of genes is demonstrated to be a cause of ND, however, the mechanisms of permanent hyperglycemia are different. This review will give an overview of more frequent genetic mutations causing ND, including the function of the mutated genes and the specific therapy for certain sub-forms.

Emerging technologies in pediatrics: the paradigm of neonatal diabetes mellitus

In the era of precision medicine, the tremendous progress in next-generation sequencing technologies has allowed the identification of an ever-increasing number of genes associated with known Mendelian disorders. Neonatal diabetes mellitus is a rare, genetically heterogeneous endocrine disorder diagnosed before 6 months of age. It may occur alone or in the context of genetic syndromes. Neonatal diabetes mellitus has been linked with genetic defects in at least 26 genes to date. Novel mutations in these disease-causing genes are being reported, giving us a better knowledge of the molecular events that occur upon insulin biosynthesis and secretion from the pancreatic β-cell. Of great importance, some of the identified genes encode proteins that can be therapeutically targeted by drugs per os, leading to transitioning from insulin to sulfonylureas. In this review, we provide an overview of pancreatic β-cell physiology, present the clinical manifestations and the genetic causes of the different forms of neonatal diabetes, and discuss the application of next-generation sequencing methods in the diagnosis and therapeutic management of neonatal diabetes and on research in this area.