Molecular and phenotypic characteristics of maturity-onset diabetes of the young compared with early onset type 2 diabetes in China

Epidemiology and phenotypes of diabetes in children and adolescents in non-European-origin populations in or from Western Pacific region

BACKGROUND

Type 1 diabetes (T1D) incidence varies substantially between countries/ territories, with most studies indicating increasing incidence. In Western Pacific region (WPR), reported rates are much lower than European-origin populations. In contrast, there are reports of substantial numbers of young people with type 2 diabetes (T2D). A deeper understanding of T1D and T2D in the WPR may illuminate factors important in pathogenesis of these conditions. Furthermore, with varying resources and funding for diabetes treatment in this region, there is a need to more clearly determine the current burden of disease and also any gaps in knowledge.

AIM

To compile and summarise published epidemiologic and phenotypic data on childhood diabetes in non-European populations in and from WPR.

METHODS

Research articles were systematically searched from PubMed (MEDLINE), Embase, Cochrane library, and gray literature. Primary outcome measures were incidence and prevalence, with secondary measures including phenotypic descriptions of diabetes, including diabetes type categorization, presence of diabetic ketoacidosis (DKA) at onset, autoantibody positivity, C-peptide levels, and human leucocyte antigen phenotype. Extracted data were collected using a customized template. Three hundred and thirty relevant records were identified from 16 countries/territories, with analysis conducted on 265 (80.3%) records published from the year 2000.

RESULTS

T1D incidence ranged from < 1-7.3/100000 individuals/year, rates were highest in emigrant/ mixed populations and lowest in South-East Asia, with most countries/territories (71.4%) having no data since 1999. Incidence was increasing in all six countries/territories with data (annual increases 0.5%-14.2%, highest in China). Peak age-of-onset was 10-14 years, with a female case excess. Rate of DKA at onset varied from 19.3%-70%. Pancreatic autoantibodies at diagnosis were similar to European-origin populations, with glutamic acid decarboxylase-65 autoantibody frequency of 44.1%-64.5%, insulinoma-associated 2 autoantibody 43.5%-70.7%, and zinc transporter-8 autoantibody frequency 54.3% (one study). Fulminant T1D also occurs. T2D was not uncommon, with incidence in Japan and one Chinese study exceeding T1D rates. Monogenic forms also occurred in a number of countries.

CONCLUSION

T1D is less common, but generally has a classic phenotype. Some countries/ territories have rapidly increasing incidence. T2D is relatively common. Registries and studies are needed to fill many information gaps.

When do we need to suspect maturity onset diabetes of the young in patients with type 2 diabetes mellitus?

OBJECTIVE

Maturity onset diabetes of the young (MODY) patients have clinical heterogeneity as shown by many studies. Thus, often it is misdiagnosed to type 1 or type 2 diabetes(T2DM). The aim of this study is to evaluate MODY mutations in adult T2DM patients suspicious in terms of MODY, and to show clinical and laboratory differences between these two situations.

METHODS

In this study, we analyzed 72 type 2 diabetic patients and their relatives (35F/37M) who had been suspected for MODY and referred to genetic department for mutation analysis. The gene mutations for MODY have been assessed in the laboratory of Marmara University genetics. Totally 67 (32F/35M; median age 36.1) diabetic patients were analyzed for 7 MODY mutations. Twelve patients who have uncertain mutation (VUS) were excluded from study for further evaluation. MODY(+) (n:30) patients and T2DM patients (n:25) were compared for clinical and laboratory parameters.

RESULTS

In MODY(+) subjects, mutations in GCK (MODY 2) (n:12; 40%) were the most common followed by HNF4A (MODY 1) (n:4; 13.3%). Diabetes diagnosis age was younger in MODY(+) group but not statistically significant. Sixty-six percent of MODY(+) subjects had diabetes history at 3-consecutive generations in their family compared with 28% of T2DM patients statistically significant (p:0.006). Gender, BMI, C-peptide, HbA1c, lipid parameters, creatinine, GFR, microalbuminuria, vitamin D and calcium were not statistically different between the groups.

CONCLUSION

According to present study results, MODY mutation positivity is most probable in young autoantibody (-) diabetic patients diagnosed before 30 years of age, who have first degree family history of diabetes.

Missense Variants in PAX4 Are Associated with Early-Onset Diabetes in Chinese

INTRODUCTION

East Asians are more susceptible to early-onset diabetes than Europeans and exhibit reduced insulin secretion at earlier stages. PAX4 plays a critical role in the development of β-cells. The dysfunction-missense variants PAX4 R192H and PAX4 R192S are common in East Asians but rare in Europeans. Therefore, we aim to investigate the diabetes-associated genes, including PAX4 R192H/S, in East Asians with early-onset diabetes.

METHODS

Exome variants of 80 Chinese early-onset diabetes patients (onset age < 35 years) after the exclusion of type 1 diabetes (T1D) were detected by a customized gene panel covering 32 known diabetes-associated genes. Then, 229 subjects with early-onset diabetes (T1D excluded) and 1679 controls from the Chinese population were genotyped to validate the association of PAX4 R192H/S with early-onset diabetes and related phenotypes.

RESULTS

The gene panel detected 11 monogenic diabetes patients with five novel mutations among the 80 early-onset diabetes patients. Asian-specifically enriched PAX4 R192H and R192S were associated with early-onset diabetes (R192H: OR 1.88, 95% CI 1.37-2.60, P = 8.41 × 10^-5; R192S: OR 1.71, 95% CI 1.17-2.51, P = 0.005). In early-onset diabetes patients, PAX4 R192H carriers had higher haemoglobin A1c (HbA1c) levels (P = 0.030) and lower 2 h C-peptide levels in the oral glucose tolerance test (OGTT) (P = 0.040); R192S carriers had lower fasting C-peptide (FCP) (P = 0.011) and 2 h C-peptide levels (P = 0.033) in OGTT than non-variant carriers.

CONCLUSIONS

The ethnic-specific enrichment of PAX4 R192H/S predisposing East Asians to early-onset diabetes with decreased C-peptide levels may be one explanation of the discrepancy of diabetes between East Asians and Europeans.

CLINICAL TRIAL REGISTRATION

ClinicalTrials.gov (NCT01938365).

Molecular Genetic Study in a Cohort of Iranian Families Suspected to Maturity-Onset Diabetes of the Young, Reveals a Recurrent Mutation and a High-Risk Variant in the CEL Gene

Background

Diabetes mellitus (DM) is a group of metabolic disorders in the body, accompanied with increasing blood sugar levels. Diabetes is classified into three groups: Type 1 DM (T1DM), Type 2 DM (T2DM), and monogenic diabetes. Maturity-onset diabetes of the young (MODY) is a monogenic diabetes that is frequently mistaken for T1D or T2D. The aim of this study was to diagnose MODY and its subtype frequency in a diabetic population in Iran.

Materials and Methods

In this study among ten diabetic families that were highly suspected to MODY by nongenetic biomarkers and without any pathogenic mutation in GCK and HNF1A genes, two patients from two unrelated families were examined via whole-exome sequencing (WES) in order to detect the causative gene of diabetes. Co-segregation analysis of the identified variant was performed using Sanger sequencing.

Results

In this study, no pathogenic variant was found in GCK and HNF1A genes (MODY2 and MODY3), while these two types of MODY were introduced as the most frequent in other studies. By using WES, a pathogenic variant (p.I488T) was found in one of the patients in CEL gene causing MODY8 that its frequency is very rare in other studied populations. A high-risk variant associated with diabetes was found in another patient.

Conclusion

WES was applied in this study to reveal the cause of MODY in 1 family. This pathogenic mutation was previously reported as a disease causing mutation.

Molecular diagnosis of maturity-onset diabetes of the young in a cohort of Chinese children

OBJECTIVE

The purpose of this study was to investigate the molecular basis of maturity-onset diabetes of the young (MODY) by whole-exome sequencing (WES) and estimate the frequency and describe the clinical characteristics of MODY in southern China.

METHODS

Genetic analysis was performed in 42 patients with MODY aged 1 month to 18 years among a cohort of 759 patients with diabetes, identified with the following four clinical criteria: age of diagnosis ≤18 years; negative pancreatic autoantibodies; family history of diabetes; or persistently detectable C-peptide; or diabetes associated with extrapancreatic features. GCK gene mutations were first screened by Sanger sequencing. GCK mutation-negative patients were further analyzed by WES.

RESULTS

Mutations were identified in 24 patients: 20 mutations in GCK, 1 in HNF4A, 1 in INS, 1 in ABCC8, and a 17q12 microdeletion. Four previously unpublished novel GCK mutations: c.1108G>C in exon 9, and c.1339C>T, c.1288_1290delCTG, and c.1340_1343delGGGGinsCTGGTCT in exon 10 were detected. WES identified a novel missense mutation c.311A>G in exon 3 in the INS gene, and copy number variation analysis detected a 1.4 Mb microdeletion in the long arm of the chromosome 17q12 region. Compared with mutation-negative subjects, the mutation-positive subjects had lower hemoglobin A1c and initial blood glucose levels.

CONCLUSIONS

Most MODY cases in this study were due to GCK mutations, which is in contrast to previous reports in Chinese patients. Diabetes associated with extrapancreatic features should be a clinical criterion for MODY genetic analysis. Mutational analysis by WES provided a precise diagnosis of MODY subtypes. Moreover, WES can be useful for detecting large deletions in coding regions in addition to point mutations.

Identification of Maturity-Onset Diabetes of the Young Caused by Mutation in FOXM1 via Whole-Exome Sequencing in Northern China

Diabetes mellitus is a highly heterogeneous disorder encompassing different types with particular clinical manifestations, while maturity-onset diabetes of the young (MODY) is an early-onset monogenenic diabetes. Most genetic predisposition of MODY has been identified in European and American populations. A large number of Chinese individuals are misdiagnosed due to defects of unknown genes. In this study, we analyzed the genetic and clinical characteristics of the Northern China. A total of 200 diabetic patients, including 10 suspected MODY subjects, were enrolled, and the mutational analysis of monogenic genes was performed by whole-exome sequencing and confirmed by familial information and Sanger sequencing. We found that clinical features and genetic characteristics have varied widely between MODY and other diabetic subjects in Northern China. FOXM1, a key molecule in the proliferation of pancreatic β-cells, has a rare mutation rs535471991, which leads to instability within the phosphorylated domain that impairs its function. Our findings indicate that FOXM1 may play a critical role in MODY, which could reduce the misdiagnose rate and provide promising therapy for MODY patients.

ABCC8-Related Maturity-Onset Diabetes of the Young (MODY12): A Report of a Chinese Family

Maturity-onset diabetes mellitus of the young (MODY) is a monogenic diabetes characterized by autosomal dominant inheritance. Its atypical clinical features make diagnosis difficult and it can be misdiagnosed as type 1 or type 2 diabetes. Fourteen subtypes of MODY have been diagnosed so far, of which MODY12 is caused by mutation of the ABCC8 (ATP Binding Cassette Subfamily C Member 8) gene, which is rarely reported in China. This paper reports a Chinese family of MODY12 caused by a rare missense mutation on the ABCC8 gene, which has not been reported to be associated with MODY in China or in other countries, with the aim of increasing clinicians' awareness and attention to the disease.

Maturity onset diabetes of the young (MODY) in Chinese children: genes and clinical phenotypes

Background To investigate the clinical and molecular characteristics of Chinese children with maturity onset diabetes of the young (MODY). Methods A total of 42 Chinese patients suspected MODY referred to our unit from 2014 to 2018 were enrolled. Mutational analysis of monogenic diabetes mellitus genes was performed by next-generation sequencing and confirmed by Sanger sequencing. Results There were 28 males (66.7%) and 14 females (33.3%) with a mean age of 9.49 ± 3.46 years (range, 1.4-15.3 years) and a mean birth weight of 3.38 ± 0.49 kg (range, 2.55-4.90 kg). Among these patients, 15 patients had polyuria, polydipsia or weight loss. Two patients (4.8%) were obese and six (14.3%) were overweight. Moreover, 13 patients (30.9%) had a family history of diabetes. Thirty variants were identified in 28 patients. Twenty-six variants in 25 patients were pathogenic or likely pathogenic genes (59.5%, 25/42), including 15 patients (60.0%, 15/25) with GCK mutation, four (16.0%, 4/25) with PAX4 mutation, three (12.0%, 3/25) with HNF4A mutation, one (4.0%, 1/25) with INS mutation, one (4.0%, 1/25) with NEUROD1 mutation and one (4.0%, 1/25) with HNF1A mutation. Nine mutations (36.0%, 9/25) were novel. There was no difference between mutation-suspected patients and MODY-confirmed patients except for a 2-h glucose increment in an oral glucose tolerance test (OGTT), while the GCK-MODY had lower glycated hemoglobin (HbA1c) and a significantly smaller 2-h glucose increment in an OGTT compared with transcription factor MODYs. The GCK-MODY was identified by incidental hyperglycemia without glycosuria. GCK-MODY without drug management and hepatocyte nuclear factor-1 alpha (HNF4A) or HNF1A-MODY with sulfonylurea therapy obtained good glucose controlling. Conclusions Mutation of the GCK gene is the most common in MODY patients in China followed by PAX4. The screening criteria can improve the cost-effectiveness of disease diagnosis and treatment. A precise molecular diagnosis would lead to optimal treatment of the patients.

Quantitative Evaluation of Serum Proteins Uncovers a Protein Signature Related to Maturity-Onset Diabetes of the Young (MODY)

Maturity-onset diabetes of the young (MODY) is an inherited monogenic type of diabetes. Genetic mutations in MODY often cause nonsynonymous changes that directly lead to the functional distortion of proteins and the pathological consequences. Herein, we proposed that the inherited mutations found in a MODY family could cause a disturbance of protein abundance, specifically in serum. The serum samples were collected from a Uyghur MODY family through three generations, and the serum proteins after depletion treatment were examined by quantitative proteomics to characterize the MODY-related serum proteins followed by verification using target quantification of proteomics. A total of 32 serum proteins were preliminarily identified as the MODY-related. Further verification test toward the individual samples demonstrated the 12 candidates with the significantly different abundance in the MODY patients. A comparison of the 12 proteins among the sera of type 1 diabetes, type 2 diabetes, MODY, and healthy subjects was conducted and revealed a protein signature related with MODY composed of the serum proteins such as SERPINA7, APOC4, LPA, C6, and F5.

GCK mutations in Chinese MODY2 patients: a family pedigree report and review of Chinese literature

BACKGROUND

Maturity-onset diabetes of the young type 2 (MODY2) is caused by mutations in the glucokinase (GCK) gene and is rare in the Chinese population. We report three Chinese families with MODY2 and the sequencing of the GCK gene.

METHODS

Three unrelated Chinese families with MODY2 and their pedigrees were investigated. In Family 1, the proband was a 7-year-old girl with impaired fasting glucose (IFG) and impaired glucose tolerance (IGT). Her mother and maternal grandfather had IFG. In Family 2, the proband was a boy who had diabetes mellitus at 11 years. His sister had IFG. His father and grandmother had diabetes mellitus at 22 and 25 years, respectively. In Family 3, the proband was a boy who had IFG and IGT at 12 years. His sister had diabetes mellitus at 8 years. His father and grandfather had IFG and/or IGT. The GCK gene was directly sequenced.

RESULTS

Diabetes mellitus or IFG/IGT was found among three consecutive generations in three families. One novel nonsense heterozygous mutation in exon 5 (c.556 C>T, p.Arg 186 stop) was detected in Family 1. Another novel frameshift mutation in exon 4 (c.367-374dupTTCGACTA, p.Ile 126 fs) was found in Family 2. A previously reported, a missense heterozygous mutation in exon 5 (c.571 C>T, p.Arg 191Trp) was detected in Family 3.

CONCLUSIONS

The thorough investigation of three Chinese families with MODY2 revealed two novel mutations and one known mutation. GCK gene sequencing helps in MODY2, especially when there is uncertain IFG or IGT.

Identification of HNF4A Mutation p.T130I and HNF1A Mutations p.I27L and p.S487N in a Han Chinese Family with Early-Onset Maternally Inherited Type 2 Diabetes

Maturity-onset diabetes of the young (MODY) is characterized by the onset of diabetes before the age of 25 years, positive family history, high genetic predisposition, monogenic mutations, and an autosomal dominant mode of inheritance. Here, we aimed to investigate the mutations and to characterize the phenotypes of a Han Chinese family with early-onset maternally inherited type 2 diabetes. Detailed clinical assessments and genetic screening for mutations in the HNF4α, GCK, HNF-1α, IPF-1, HNF1β, and NEUROD1 genes were carried out in this family. One HNF4A mutation (p.T130I) and two HNF1A polymorphisms (p.I27L and p.S487N) were identified. Mutation p.T130I was associated with both early-onset and late-onset diabetes and caused downregulated HNF4A expression, whereas HNF1A polymorphisms p.I27L and p.S487N were associated with the age of diagnosis of diabetes. We demonstrated that mutation p.T130I in HNF4A was pathogenic as were the predicted polymorphisms p.I27L and p.S487N in HNF1A by genetic and functional analysis. Our results show that mutations in HNF4A and HNF1A genes might account for this early-onset inherited type 2 diabetes.