A case report of Maturity-onset diabetes of the young 12: large fragment deletion in ABCC8 gene with literature review

Background

Maturity-onset diabetes of the young (MODY) is one type of monogenic diabetes that is often misdiagnosed. The case refers to a case of maturity-onset diabetes of the young 12 (MODY12) who was misdiagnosed with type 1 diabetes (T1DM), and this was the first case of MODY12 induced by a large deletion of the ATP-binding cassette transporter C8 gene (ABCC8). Additionally, a literature review was conducted regarding the pathological mechanisms, clinical manifestations, diagnosis, and treatment of ABCC8-mutated diabetes.

Case Description

A 22 years old, male patient had been misdiagnosed with T1DM for 4 years and had experienced poor glucose control with multiple daily insulin injections. Their glycated hemoglobin (HbA1c) was 12.9% at the time of admission and they had been experiencing frequent hypoglycemia. Next-generation sequencing found that the chr11p15.1 region had large fragment heterozygous deletion of exon 17 of the ABCC8 gene. According to the genetic test results, the patient was diagnosed as MODY12, insulin treatment was gradually stopped and converted to glimepiride for oral administration, and HbA1c decreased to 6.1%. After oral treatment for 8 months, the glimepride was stopped; however, HbA1c was 5.9% after 6 months of drug withdrawal and C-peptide level became elevated [fasting C-peptide (FCP) increase from 0.8 to 7.5 ng/mL, and 2 h postprandial C-peptide increase from 0.7 to. 4.1 ng/mL].

Conclusions

It is easy for underweight MODY patients to be misdiagnosed with T1DM. For T1DM patients with poor insulin treatment effects, repeated hypoglycemia, and persistent insulin secretion level, ABCC8 or other genes related to monogenic diabetes should be screened. An early diagnosis and transition of treatment can help improve prognosis.

Molecular mechanisms of β-cell dysfunction and death in monogenic forms of diabetes

Monogenetic forms of diabetes represent 1%-5% of all diabetes cases and are caused by mutations in a single gene. These mutations, that affect genes involved in pancreatic β-cell development, function and survival, or insulin regulation, may be dominant or recessive, inherited or de novo. Most patients with monogenic diabetes are very commonly misdiagnosed as having type 1 or type 2 diabetes. The severity of their symptoms depends on the nature of the mutation, the function of the affected gene and, in some cases, the influence of additional genetic or environmental factors that modulate severity and penetrance. In some patients, diabetes is accompanied by other syndromic features such as deafness, blindness, microcephaly, liver and intestinal defects, among others. The age of diabetes onset may also vary from neonatal until early adulthood manifestations. Since the different mutations result in diverse clinical presentations, patients usually need different treatments that range from just diet and exercise, to the requirement of exogenous insulin or other hypoglycemic drugs, e.g., sulfonylureas or glucagon-like peptide 1 analogs to control their glycemia. As a consequence, awareness and correct diagnosis are crucial for the proper management and treatment of monogenic diabetes patients. In this chapter, we describe mutations causing different monogenic forms of diabetes associated with inadequate pancreas development or impaired β-cell function and survival, and discuss the molecular mechanisms involved in β-cell demise.

[Association of polymorphisms of genes TCF7L2, FABP2, KCNQ1, ADIPOQ with the prognosis of the development of type 2 diabetes mellitus]

AIM

To study the possibility of using polymorphisms of genesTCF7L2,FABP2,KCNQ1,ADIPOQas markers for predicting the development of type 2 diabetes mellitus (T2D) in the population of Novosibirsk.

MATERIALS AND METHODS

On the basis of prospective observation of a representative population sample of residents of Novosibirsk (HAPIEE), 2 groups were formed according to the case-control principle (case people who had diabetes mellitus 2 over 10 years of observation, and control people who did not developed disorders of carbohydrate metabolism). T2D group (n=443, mean age 56.26.7 years, men 29.6%, women 70.4%), control group (n=532, mean age 56.17.1 years, men 32.7%, women 67.3%). DNA was isolated by phenol-chloroform extraction. Genotyping was performed by the method of polymerase chain reaction with subsequent analysis of restriction fragment length polymorphism, polymerase chain reaction in real time. Statistical processing was carried out using the SPSS 16.0 software package.

RESULTS AND DISCUSSION

No significant effect of rs1799883 of theFABP2gene, rs2237892 of theKCNQ1gene, and rs6773957 of theADIPOQgene on the risk of developing T2D was found. Genotypes TT and TC rs7903146 of theTCF7L2gene are genotypes for the risk of developing T2D (relative risk RR 3.90, 95% confidence interval CI 2.316.61,p0.001; RR 1.86, 95% CI 1.422.43,p0.001, respectively). The CC genotype rs7903146 of theTCF7L2gene is associated with a protective effect against T2D (RR 0.37, 95% CI 0.290.49,p0.001). When theTCF7L2gene is included in the model for assessing the risk of developing T2D rs7903146, it retains its significance in both men and women.

CONCLUSION

The rs7903146 polymorphism of theTCF7L2gene confirmed its association with the prognosis of the development of T2D, which indicates the possibility of considering it as a candidate for inclusion in a diabetes risk meter. Variants of risk meters have been developed to assess the prognosis of the development of diabetes mellitus 2 in men and women aged 4569 years during 10 years of follow-up. The association with the prognosis of the development of T2D polymorphisms rs1799883 of theFABP2gene, rs2237892 of theKCNQ1gene and rs6773957 of theADIPOQgene was not found.

A Case of Maturity Onset Diabetes of the Young (MODY3) in a Family with a Novel HNF1A Gene Mutation in Five Generations

Diabetes mellitus with autosomal dominant inheritance, i.e., maturity-onset diabetes of the young (MODY), is a genetic form of diabetes mellitus. The MODY phenotype is associated with gene mutations leading to pancreatic β-cell dysfunction. Here, we present the clinical case of a 50-year-old proband with familial diabetes mellitus in five generations (proband, her mother, grandmother, great-grandfather, and son). This disease is most likely associated with the novel Ser6Arg mutation in the HNF1A gene, which was identified in four family members. The mutation was not detected in MODY patients (126 subjects), in patients with type 2 diabetes mellitus (188 subjects), and in a general population sample (564 subjects).

ABCC8-Related Maturity-Onset Diabetes of the Young (MODY12): Clinical Features and Treatment Perspective

Maturity-onset diabetes of the young (MODY) is a heterogeneous group of diseases associated with gene mutations leading to dysfunction of pancreatic β-cells. Thirteen identified MODY variants differ from each other by the clinical course and treatment requirement. Currently, MODY subtypes 1-5 are best-studied, descriptions of the other forms are sporadic. This article reports a MODY12 clinical case, caused by a mutation in the gene of the ATP-binding cassette transporter sub-family C member 8 (ABCC8), encoding sulfonylurea receptor 1. Diabetes manifested in a 27-year-old non-obese man with epilepsy in anamnesis. No evidence of ketosis was present, pancreatic antibodies were undetectable, and C-peptide remained within the reference range. During the initial investigation, non-proliferative diabetic retinopathy and elevated albumin excretion rate was revealed. After 4 months, diabetes was complicated by pre-proliferative retinopathy and diabetic macular edema. Recurrent hypoglycemia and an increase in body weight was observed on moderate and even small insulin doses. Taking into account the clinical features and the presence of diabetes in four generations on the maternal side, screening for all MODY subtypes was performed. A mutation in the ABCC8 gene was found in proband and in his mother. After the insulin discontinuation, gliclazide modified release combined with sodium/glucose cotransporter 2 (SGLT2) inhibitors was started. This treatment eliminated hypoglycemia and improved glycemic variability parameters. A decrease in the amplitude of glucose excursions was documented by continuous glucose monitoring. After 3 months of treatment, glycemic control was still optimal, and no hypoglycemic episodes were observed. The case report demonstrates the clinical features of ABCC8-associated MODY and the therapeutic potential of a combination of sulfonylurea with SGLT2 inhibitor in this disease.