Systematic Population Screening, Using Biomarkers and Genetic Testing, Identifies 2.5% of the U.K. Pediatric Diabetes Population With Monogenic Diabetes

Monogenic diabetes: An evidence-based clinical approach

Monogenic diabetes is a heterogeneous disorder characterized by hyperglycemia arising from defects in a single gene. Maturity-onset diabetes of the young (MODY) is the most common type with 14 subtypes, each linked to specific mutations affecting insulin synthesis, secretion and glucose regulation. Common traits across MODY subtypes include early-onset diabetes, a family history of autosomal dominant diabetes, lack of features of insulin resistance, and absent islet cell autoimmunity. Many cases are misdiagnosed as type 1 and type 2 diabetes mellitus. Biomarkers and scoring systems can help identify candidates for genetic testing. GCK-MODY, a common subtype, manifests as mild hyperglycemia and doesn’t require treatment except during pregnancy. In contrast, mutations in HNF4A, HNF1A, and HNF1B genes lead to progressive beta-cell failure and similar risks of complications as type 2 diabetes mellitus. Neonatal diabetes mellitus (NDM) is a rare form of monogenic diabetes that usually presents within the first six months. Half of the cases are lifelong, while others experience transient remission. Permanent NDM is most commonly due to activating mutations in genes encoding the adenosine triphosphate-sensitive potassium channel (KCNJ11 or ABCC8) and can be transitioned to sulfonylurea after confirmation of diagnosis. Thus, in many cases, monogenic diabetes offers an opportunity to provide precision treatment. The scope has broadened with next-generation sequencing (NGS) technologies, replacing older methods like Sanger sequencing. NGS can be for targeted gene panels, whole-exome sequencing (WES), or whole-genome sequencing. Targeted gene panels offer specific information efficiently, while WES provides comprehensive data but comes with bioinformatic challenges. The surge in testing has also led to an increase in variants of unknown significance (VUS). Deciding whether VUS is disease-causing or benign can be challenging. Computational models, functional studies, and clinical knowledge help to determine pathogenicity. Advances in genetic testing technologies offer hope for improved diagnosis and personalized treatment but also raise concerns about interpretation and ethics.

Unraveling the genetic basis of MODY: insights from next-generation sequencing

Maturity-onset diabetes of the young (MODY) is an uncommon kind of monogenic diabetes. The major characteristics of MODY include not having insulin resistance and the absence of autoimmunity, early onset, and a family history suggesting autosomal-dominant inheritance. Nonetheless, genetic testing is necessary for diagnosis. The MODY-related genes CEL, ABCC8, PDX1, GCK, WFS1, HNF4A, HNF1A, and HNF1B were examined using Next Generation Sequencing (NGS) in this investigation. This study aimed to evaluate the genetic and clinical characteristics of patients referred with a preliminary diagnosis of MODY, retrospectively. A total of 30 patients (18 male and 12 female) participated, with ages ranging from 5 to 56. Eight distinct genetic variants were identified in 17 cases (57%). Pathogenic variants in the HNF1A gene have been identified. Likely pathogenic variants were found in CEL, ABCC8, GCK, and HNF4A. The genes APPL1, BLK, INS, KCNJ1, KLF11, NEUROD1, PAX4, RFX6, and ZFP57 were shown to be mutation-free. Four distinct pathogenic variants are found in this series. Unexpectedly high rates of pathogenic variants have been found in the HNF1A gene. In 27% of cases, there is a family history of vertically transmitted diabetes. The study highlights the importance of genetic testing for individuals with early-onset diabetes and a strong family history of the condition. Comprehensive genetic testing and increased public awareness are essential for MODY.

Review of Monogenic Diabetes: Clinical Features and Precision Medicine in Genetic Forms of Diabetes

Monogenic diabetes is a group of diseases that encompasses a growing number of genetic abnormalities affecting pancreatic function/development leading to glycemic dysregulation. This includes conditions that have historically been referred to as maturity onset diabetes of the young or MODY in addition to neonatal diabetes mellitus. While recognition of a genetic or inherited form of diabetes has been known for decades, advances in molecular genetic testing have resulted in identification of specific forms of monogenic diabetes. Despite this, these genetic forms of diabetes remain widely underreported. It is important to be able to identify genetic forms of diabetes as treatment, monitoring for microvascular and macrovascular complications, and overall management varies for the different forms of monogenic diabetes. Furthermore, the identification of a specific monogenic form of diabetes can significantly impact the person's quality of life and other family members, as well as health care costs. This article highlights the identification, treatment, and management for various forms of monogenic diabetes and addresses some unmet needs in caring for people with monogenic forms of diabetes.

A case report of a MODY6 patient coexistence with Charcot-Marie-Toothe 1A syndrome

Monogenic diabetes, which encompasses neonatal diabetes (NDM), maturity onset diabetes of the young (MODY), and several diabetes-associated syndromes, primarily arises from impaired function or abnormal development of the islets of Langerhans, particularly pancreatic β-cells responsible for insulin secretion. This condition is typically associated with a single pathogenic genetic mutation. Charcot-Marie-Tooth disease type 1A (CMT1A) is a hereditary demyelinating neuropathy that is caused by a duplication of the PMP22 gene located on chromosome 17. Herein, we report a case of a young Chinese patient with MODY6 harboring a novel mutation (c. 317C>T, p. Ala106Val) in the NEUROD1 gene. Additionally, this patient concurrently presents with CMT1A, which is characterized by a large segmental duplication within the exon of the PMP22 gene and its adjacent regions. Considering the patient's compromised islet function, we treat him with insulin and oral hypoglycemic agents (metformin, acarbose). This represents the first reported instance of a patient with NEUROD1-MODY coexisting with CMT1A.

Pathogenetic therapeutic approaches for endocrine diseases based on antisense oligonucleotides and RNA-interference

Molecular therapy uses nucleic acid-based therapeutics agents and becomes a promising alternative for disease conditions unresponsive to traditional pharmaceutical approaches. Antisense oligonucleotides (ASOs) and small interfering RNAs (siRNAs) are two well-known strategies used to modulate gene expression. RNA-targeted therapy can precisely modulate the function of target RNA with minimal off-target effects and can be rationally designed based on sequence data. ASOs and siRNA-based drugs have unique capabilities for using in target groups of patients or can be tailored as patient-customized N-of-1 therapeutic approach. Antisense therapy can be utilized not only for the treatment of monogenic diseases but also holds significant promise for addressing polygenic and complex diseases by targeting key genes and molecular pathways involved in disease pathogenesis. In the context of endocrine disorders, molecular therapy is particularly effective in modulating pathogenic mechanisms such as defective insulin signaling, beta-cell dysfunction and hormonal imbalances. Furthermore, siRNA and ASOs have the ability to downregulate overactive signaling pathways that contribute to complex, non-monogenic endocrine disorders, thereby addressing these conditions at their molecular origin. ASOs are also being studied worldwide as unique candidates for developing therapies for N-of-1 therapies. The sequence-specific ASOs binding provides exceptional accuracy in N-of-1 approaches, when the oligonucleotide can be targeted to a patient's exact mutant sequence. In this review we focus on diseases of the endocrine system and discuss potential RNA-targeted therapeutic opportunities in diabetes mellitus, including monogenic beta cell diabetes, and obesity, including syndrome obesity and monogenic obesity, as well as in non-monogenic or complex endocrine disorders. We also provide an overview of currently developed and available antisense molecules, and describe potentials of antisense-based therapeutics for the treatment of rare and «ultrarare» endocrine diseases.

Current views on etiology, diagnosis, epidemiology and gene therapy of maturity onset diabetes in the young

MODY, or maturity-onset diabetes of the young, is a group of monogenic diseases characterized by autosomal dominant inheritance of a non-insulin-dependent form of diabetes that classically manifests in adolescence or in young adults under 25 years of age. MODY is a rare cause of diabetes, accounting for 1% of all cases, and is often misdiagnosed as type 1 or type 2 diabetes. It is of great importance to accurately diagnose MODY, as this allows for the most appropriate treatment of patients and facilitates early diagnosis for them and their families. This disease has a high degree of phenotypic and genetic polymorphism. The most prevalent forms of the disease are attributed to mutations in three genes: GCK (MODY 2) and (HNF)1A/4A (MODY 3 and MODY 1). The remaining MODY subtypes, which are less prevalent, have been identified by next generation sequencing (NGS) in the last decade. Mutations in the GCK gene result in asymptomatic, stable fasting hyperglycemia, which does not require specific treatment. Mutations in the HNF1A and HNF4A genes result in pancreatic β-cell dysfunction, which in turn causes hyperglycemia. This often leads to diabetic angiopathy. The most commonly prescribed drugs for the treatment of hyperglycemia are sulfonylurea derivatives. Nevertheless, with advancing age, some patients may require insulin therapy due to the development of resistance to sulfonylurea drugs. The strategy of gene therapy for monogenic forms of MODY is still an experimental approach, and it is unlikely to be widely used in the clinic due to the peculiarities of MODY structure and the high genetic polymorphism and clinical variability even within the same form of the disease. Furthermore, there is a lack of clear gene-phenotypic correlations, and there is quite satisfactory curability in the majority of patients. This review presents the main clinical and genetic characteristics and mutation spectrum of common and rarer forms of MODY, with a detailed analysis of the field of application of AVV vectors in the correction of hyperglycemia and insulin resistance.

Advancing Monogenic Diabetes Research and Clinical Care by Creating a Data Commons: The Precision Diabetes Consortium (PREDICT)

Monogenic diabetes mellitus (MDM) is a group of relatively rare disorders caused by pathogenic variants in key genes that result in hyperglycemia. Lack of identified cases, along with absent data standards, and limited collaboration across institutions have hindered research progress. To address this, the UChicago Monogenic Diabetes Registry (UCMDMR) and UChicago Data for the Common Good (D4CG) created a national consortium of MDM research institutions called the PREcision DIabetes ConsorTium (PREDICT). Following the D4CG model, PREDICT has successfully established a multicenter MDM data commons. PREDICT has created a consensus data dictionary that will be utilized to address critical gaps in understanding of these rare types of diabetes. This approach may be useful for other rare conditions that would benefit from access to harmonized pooled data.

Prequalification of genome-based newborn screening for severe childhood genetic diseases through federated training based on purifying hyperselection

Genome-sequence-based newborn screening (gNBS) has substantial potential to improve outcomes in hundreds of severe childhood genetic disorders (SCGDs). However, a major impediment to gNBS is imprecision due to variants classified as pathogenic (P) or likely pathogenic (LP) that are not SCGD causal. gNBS with 53,855 P/LP variants, 342 genes, 412 SCGDs, and 1,603 therapies was positive in 74% of UK Biobank (UKB470K) adults, suggesting 97% false positives. We used the phenomenon of purifying hyperselection, which acts to decrease the frequency of SCGD causal diplotypes, to reduce false positives. Training of gene-disease-inheritance mode-diplotype tetrads in 618,290 control and affected subjects identified 293 variants or haplotypes and seven genes with variable inheritance contributing higher positive diplotype counts than consistent with purifying hyperselection and with little or no evidence of SCGD causality. With these changes, 2.0% of UKB470K adults were positive. In contrast, gNBS was positive in 7.2% of 3,118 critically ill children with suspected SCGDs and 7.9% of 705 infant deaths. When compared with rapid diagnostic genome sequencing (RDGS), gNBS had 99.1% recall. In eight true-positive children, gNBS was projected to decrease time to diagnosis by a median of 121 days and avoid life-threatening disease presentations in four children, organ damage in six children, ∼$1.25 million in healthcare cost, and ten (1.4%) infant deaths. Federated training predicated on purifying hyperselection provides a general framework to attain high precision in population screening. Federated training across many biobanks and clinical trials can provide a privacy-preserving mechanism for qualification of gNBS in diverse genetic ancestries.

The Maturity-Onset Diabetes of the Young (MODY) Calculator Overestimates MODY Probability in Hispanic Youth

CONTEXT

The applicability of the MODY risk calculator (Shields et al) to non- White European populations remains unknown.

OBJECTIVE

We aimed to test its real-world application in Hispanic youth.

METHODS

We conducted a retrospective chart review of Hispanic youth (<23 years) with diabetes (n=2033) in a large pediatric tertiary care center in the U.S. We calculated MODY probability for all subjects, splitting them into two cohorts based on the original model: Individuals who were started on insulin within 6 months of diabetes diagnosis (Cohort 1) and those who were not (Cohort 2).

RESULTS

Cohort 1 consisted of 1566 individuals (median age [25p, 75p]: 16 [13, 19] years, 49% female), while Cohort 2 comprised 467 youth (median age [25p, 75p]: 17 [15, 20] years, 62% female). The mean MODY probability was 5.9% and 61.9% in Cohort 1 and Cohort 2, respectively. The mean probability for both cohorts combined was 18.8% suggesting an expected 382 individuals with MODY, which is much higher than previous estimations (1-5%; i.e. 20-102 individuals in this cohort). A total of 18 individuals tested positive for MODY among the limited number of individuals tested based on clinical suspicion and genetic testing availability (n=44 out of 2033 tested, [2.2% of overall cohort]).

CONCLUSIONS

The MODY risk calculator likely overestimates the probability of MODY in Hispanic youth, largely driven by an overestimation in those not early-insulin treated (predominantly young-onset type 2 diabetes). The calculator needs updating to improve its applicability in this population. In addition, further research to help better identify MODY in Hispanic youth.

Clinical characteristics, treatment, and treatment switch after molecular-genetic classification in individuals with maturity-onset diabetes of the young: Insights from the multicenter real-world DPV registry

BACKGROUND

Individuals with maturity-onset diabetes of the young (MODY) are often misdiagnosed as type 1 or type 2 diabetes and receive inappropriate care. We aimed to investigate the characteristics and treatment of all MODY types in a multicenter, real-world setting.

METHODS

Individuals with MODY from the diabetes prospective follow-up (DPV) registry were studied. We compared clinical parameters during the first year of diabetes and the most recent treatment year after MODY diagnosis.

RESULTS

A total of 1640 individuals were identified with GCK-MODY (n = 941) and HNF1A-MODY (n = 417) as the most frequent types. Among these, 912 individuals were available with information during the first and the most recent treatment year (median duration of follow-up: 4.2 years [2.6-6.6]). Positive beta cell autoantibodies were present in 20.6% (15.2% IAA). Median age at diagnosis ranged from 9.9 years in GCK-MODY (Q1-Q3: 6.2-13.1 years) and INS-MODY (2.7-13.7 years) to 14.3 years (5.0-17.1) in KCNJ11-MODY. Frequency of oral antidiabetic agents (OAD) use increased and insulin decreased in HNF4A-MODY (OAD: 18% to 39%, insulin: 34% to 23%) and in HNF1A-MODY (OAD: 18% to 31%, insulin: 35% to 25%). ABCC8-MODY was characterized by a decrement in nonpharmacological treatment (26% to 16%) and "insulin only" treatment (53% to 42%), while the proportion of individuals treated with OAD but no insulin increased from 0% to 21%.

CONCLUSIONS

Our results indicate that some teams caring for individuals with MODY are hesitant with regard to current recommendations. Registries are an essential source of information and provide a basis for discussing treatment guidelines for MODY.

Treatment switch from multiple daily insulin injections to sulphonylureas in an African young adult diagnosed with HNF1A MODY: a case report

BACKGROUND

Maturity onset diabetes of the young is one of the commonest causes of monogenic diabetes and can easily be mistaken for type 1 diabetes. A diagnosis of maturity onset diabetes of the young can have direct implications for genetic counseling, family screening, and precision diabetes treatment. However, the cost of genetic testing and identifying individuals to test are the main challenges for diagnosis and management in sub-Saharan Africa. We report the very first documented case of HNF1A maturity onset diabetes of the young in the sub-Saharan African region.

CASE PRESENTATION

A 20-year-old female Black African young adult diagnosed with type 1 diabetes aged 14 presented for routine out-patient diabetes consultation. She was on multiple daily insulin injections; total combined dose 0.79 IU/kg/day with an HbA1c of 7.7%. The rest of her laboratory examinations were normal. On extended laboratory analysis, she had good residual insulin secretion with post-meal plasma C-peptide levels at 1150 pmol/L. She tested negative for glutamic acid decarboxylase (GAD65), islet antigen-2 (IA-2), and zinc transporter 8 (ZnT8) islet autoantibodies. Targeted next-generation sequencing (t-NGS) for monogenic diabetes was performed using DNA extracted from a buccal sample. She was diagnosed with HNF1A maturity onset diabetes of the young, with the c.607C > T; p.(Arg203Cys) pathogenic variant, which has never been reported in sub-Saharan Africa. Her clinical practitioners provided genetic and therapeutic counseling. Within 10 months following the diagnosis of maturity onset diabetes of the young, she was successfully switched from multiple daily insulin injections to oral antidiabetic tablets (sulphonylurea) while maintaining stable glycemic control (HBA1c of 7.0%) and reducing hypoglycemia. She expressed a huge relief from the daily finger pricks for blood glucose monitoring.

CONCLUSION

This case reveals that HNF1A maturity onset diabetes of the young (and probably other causes of monogenic diabetes) can present in sub-Saharan Africa. A diagnosis of maturity onset diabetes of the young can have significant life-changing therapeutic implications.

Ciliopathies are responsible for short stature and insulin resistance: A systematic review of this clinical association regarding SOFT syndrome

SOFT syndrome (Short stature-Onychodysplasia-Facial dysmorphism-hypoTrichosis) is a rare primordial dwarfism syndrome caused by biallelic variants in POC1A encoding a centriolar protein. To refine the phenotypic spectrum of SOFT syndrome, recently shown to include metabolic features, we conducted a systematic review of all published cases (19 studies, including 42 patients). The SOFT tetrad affected only 24 patients (57%), while all cases presented with short stature from birth (median height: -5.5SDS([-8.5]-[-2.8])/adult height: 132.5 cm(103.5-148)), which was most often disproportionate (90.5%), with relative macrocephaly. Bone involvement resulted in short hands and feet (100%), brachydactyly (92.5%), metaphyseal (92%) or epiphyseal (84%) anomalies, and/or sacrum/pelvis hypoplasia (58%). Serum IGF-I was increased (median IGF-I level: + 2 SDS ([-0.5]-[+ 3])). Recombinant human growth hormone (rhGH) therapy was stopped for absence/poor growth response (7/9 patients, 78%) and/or hyperglycemia (4/9 patients, 45%). Among 11 patients evaluated, 10 (91%) presented with central distribution of fat (73%), clinical (64%) and/or biological insulin resistance (IR) (100%, median HOMA-IR: 18), dyslipidemia (80%), and hepatic steatosis (100%). Glucose tolerance abnormalities affected 58% of patients aged over 10 years. Patients harbored biallelic missense (52.4%) or truncating (45.2%) POC1A variants. Biallelic null variants, affecting 36% of patients, were less frequently associated with the SOFT tetrad (33% vs 70% respectively, p = 0.027) as compared to other variants, without difference in the prevalence of metabolic abnormalities. POC1A should be sequenced in children with short stature, altered glucose/insulin homeostasis and/or centripetal fat distribution. In patients with SOFT syndrome, rhGH treatment is not indicated, and IR-related complications should be regularly screened and monitored.PROSPERO registration: CRD42023460876.

Course of pregnancy and 10-year observation of twins diagnosed with GCK-MODY in the neonatal period: a case report

Monogenic diabetes accounts for 5% of all incidence of hyperglycemia and Maturity Onset Diabetes of the Young (MODY) is the most common form. In GCK-MODY, one of the most common forms of MODY, hyperglycemia is caused by a mutation of a gene responsible for coding glucokinase. At the clinical level, this condition presents as persistent, moderate and asymptomatic elevated fasting glucose levels and has a relatively low incidence of micro and macro-vascular complications. In general, the treatment of choice is to follow and maintain a healthy lifestyle. The incidence of GCK-MODY during pregnancy is 2% on average (0-6%). In this report, we introduce a case of a woman diagnosed with GCK-MODY during the pregnancy with twins, a boy and a girl, diagnosed with GCK-MODY after birth. We discuss the course of pregnancy, the need for access to fast and uncomplicated genetic diagnostics in utero, and the impact of the MODY diagnosis on the life of the mother and that of her children. In our case, the diagnosis of GCK-MODY was associated with a feeling of relief, after years of uncertainty, and helped to introduce more appropriate eating behaviors and lifestyle changes for both the mother and her children.

Exploring the genetic basis of childhood monogenic diabetes

Monogenic diabetes is caused by one or even more genetic variations, which may be uncommon yet have a significant influence and cause diabetes at an early age. Monogenic diabetes affects 1% to 5% of children, and early detection and genetically focused treatment of neonatal diabetes and maturity-onset diabetes of the young can significantly improve long-term health and well-being. The etiology of monogenic diabetes in childhood is primarily attributed to genetic variations affecting the regulatory genes responsible for beta-cell activity. In rare instances, mutations leading to severe insulin resistance can also result in the development of diabetes. Individuals diagnosed with specific types of monogenic diabetes, which are commonly found, can transition from insulin therapy to sulfonylureas, provided they maintain consistent regulation of their blood glucose levels. Scientists have successfully devised materials and methodologies to distinguish individuals with type 1 or 2 diabetes from those more prone to monogenic diabetes. Genetic screening with appropriate findings and interpretations is essential to establish a prognosis and to guide the choice of therapies and management of these interrelated ailments. This review aims to design a comprehensive literature summarizing genetic insights into monogenetic diabetes in children and adolescents as well as summarizing their diagnosis and management.

A Korean Family Presenting with Renal Cysts and Maturity-Onset Diabetes of the Young Caused by a Novel In-Frame Deletion of HNF1B

Maturity-onset diabetes of the young (MODY; OMIM # 606391) comprises a cluster of inherited disorders within non-autoimmune diabetes mellitus (DM), typically emerging during adolescence or young adulthood. We report a novel in-frame deletion of HNF1B in a family with renal cysts and MODY, furthering our understanding of HNF1B-related phenotypes. We conducted sequential genetic testing to investigate the glucose intolerance, renal cysts, hepatic cysts, and agenesis of the dorsal pancreas observed in the proband. A comprehensive clinical exome sequencing approach using a Celemics G-Mendeliome Clinical Exome Sequencing Panel was employed. Considering the clinical manifestations observed in the proband, gene panel sequencing identified a heterozygous HNF1B variant, c.36_38delCCT/p.(Leu13del) (reference transcript ID: NM_000458.4), as the most likely cause of MODY in the proband. The patient's clinical presentation was consistent with MODY caused by the HNF1B variant, showing signs of glucose intolerance, renal cysts, hepatic cysts, and agenesis of the dorsal pancreas. Sanger sequencing confirmed the same HNF1B variant and established the paternally inherited autosomal dominant status of the heterozygous variant in the patient, as well as in his father and sister. The presence of early-onset diabetes, renal cysts, a family history of the condition, and nephropathy appearing before or after the diagnosis of diabetes mellitus (DM) suggests a diagnosis of HNF1B-MODY5. Early diagnosis is crucial for preventing complications of DM, enabling family screening, providing pre-conceptional genetic counseling, and monitoring kidney function decline.

A New Variant of the IER3IP1 Gene: The First Case of Microcephaly, Epilepsy, and Diabetes Syndrome 1 from Turkey

Microcephaly, epilepsy and diabetes syndrome 1 (MEDS1) is a rare autosomal recessive disorder caused by defects in the immediate early response 3 interacting protein 1 (IER3IP1) gene. Only nine cases have been described in the literature. MEDS1 manifests as microcephaly with simplified gyral pattern in combination with severe infantile epileptic encephalopathy and early-onset permanent diabetes. A simplified gyral pattern has been described in all cases reported to date. Diagnosis is made by demonstration of specific mutations in the IER3IP1 gene. In this study, we present an additional case of a patient with MEDS1 who was homozygous for the c.53C>T p.(Ala18Val) variant. This case, the first to be reported from Turkey, differs from other cases due to the absence of a typical simplified gyral pattern on early brain magnetic resonance imaging, the late onset of diabetes, and the presence of a new genetic variant. The triad of microcephaly, generalized seizures and permanent neonatal diabetes should prompt screening for mutations in IER3IP1.

MODY calculator applied in patients with clinical diagnosis of type 1 diabetes mellitus: Is a higher cutoff needed?

Aim

This study aimed to evaluate the mean post-test probability (PTP) of the Maturity-onset diabetes of the young (MODY) calculator in a multiethnic cohort of patients previously diagnosed with type 1 diabetes (T1DM).

Materials and methods

The MODY probability calculator proposed by Shields and colleagues (2012) was applied to 117 patients from a T1DM outpatient clinic at a tertiary hospital in Brazil. Additionally, two exons of the HNF1A gene were sequenced in eight patients who hadn't received insulin treatment within six months after the diagnosis.

Results

17.1 % of patients achieved PTP >10 %; 11.1 % achieved PTP >25 % (and all patients >30 %), and 7.7 % achieved PTP >40 %. Among the patients who were selected for genetic sequencing, 100 % presented PTP >30 %, with 66.6 % achieving PTP >40 % and 41.6 % achieving PTP >75 %. These cutoffs are as suggested for the Brazilian population, according to previous investigations. No mutation was observed in the sequenced exons.

Conclusion

Considering that only around 10 % of the evaluated cases achieved PTP >30 %, it is highly probable that the most suitable cutoff to select patients for genetic sequencing in a Brazilian cohort of T1DM is higher than the cutoff used in Caucasian populations.

Monogenic diabetes in children: An underdiagnosed and poorly managed clinical dilemma

Monogenic diabetes, constituting 1%-2% of global diabetes cases, arises from single gene defects with distinctive inheritance patterns. Despite over 50 ass-ociated genetic disorders, accurate diagnoses and management of monogenic diabetes remain inadequate, underscoring insufficient clinician awareness. The disease spectrum encompasses maturity-onset diabetes of the young (MODY), characterized by distinct genetic mutations affecting insulin secretion, and neonatal diabetes mellitus (NDM) - a heterogeneous group of severe hyperglycemic disorders in infants. Mitochondrial diabetes, autoimmune monogenic diabetes, genetic insulin resistance and lipodystrophy syndromes further diversify the monogenic diabetes landscape. A tailored approach based on phenotypic and biochemical factors to identify candidates for genetic screening is recommended for suspected cases of MODY. NDM diagnosis warrants immediate molecular genetic testing for infants under six months. Identifying these genetic defects presents a unique opportunity for precision medicine. Ongoing research aimed to develop cost-effective genetic testing methods and gene-based therapy can facilitate appropriate identification and optimize clinical outcomes. Identification and study of new genes offer a valuable opportunity to gain deeper insights into pancreatic cell biology and the pathogenic mechanisms underlying common forms of diabetes. The clinical review published in the recent issue of World Journal of Diabetes is such an attempt to fill-in our knowledge gap about this enigmatic disease.

Development of a clinical calculator to aid the identification of MODY in pediatric patients at the time of diabetes diagnosis

Maturity Onset Diabetes of the Young (MODY) is a young-onset, monogenic form of diabetes without needing insulin treatment. Diagnostic testing is expensive. To aid decisions on who to test, we aimed to develop a MODY probability calculator for paediatric cases at the time of diabetes diagnosis, when the existing "MODY calculator" cannot be used. Firth logistic regression models were developed on data from 3541 paediatric patients from the Swedish 'Better Diabetes Diagnosis' (BDD) population study (n = 46 (1.3%) MODY (HNF1A, HNF4A, GCK)). Model performance was compared to using islet autoantibody testing. HbA1c, parent with diabetes, and absence of polyuria were significant independent predictors of MODY. The model showed excellent discrimination (c-statistic = 0.963) and calibrated well (Brier score = 0.01). MODY probability > 1.3% (ie. above background prevalence) had similar performance to being negative for all 3 antibodies (positive predictive value (PPV) = 10% v 11% respectively i.e. ~ 1 in 10 positive test rate). Probability > 1.3% and negative for 3 islet autoantibodies narrowed down to 4% of the cohort, and detected 96% of MODY cases (PPV = 31%). This MODY calculator for paediatric patients at time of diabetes diagnosis will help target genetic testing to those most likely to benefit, to get the right diagnosis.

The MODY-associated KCNK16 L114P mutation increases islet glucagon secretion and limits insulin secretion resulting in transient neonatal diabetes and glucose dyshomeostasis in adults

The gain-of-function mutation in the TALK-1 K+ channel (p.L114P) is associated with maturity-onset diabetes of the young (MODY). TALK-1 is a key regulator of β-cell electrical activity and glucose-stimulated insulin secretion. The KCNK16 gene encoding TALK-1 is the most abundant and β-cell-restricted K+ channel transcript. To investigate the impact of KCNK16 L114P on glucose homeostasis and confirm its association with MODY, a mouse model containing the Kcnk16 L114P mutation was generated. Heterozygous and homozygous Kcnk16 L114P mice exhibit increased neonatal lethality in the C57BL/6J and the CD-1 (ICR) genetic background, respectively. Lethality is likely a result of severe hyperglycemia observed in the homozygous Kcnk16 L114P neonates due to lack of glucose-stimulated insulin secretion and can be reduced with insulin treatment. Kcnk16 L114P increased whole-cell β-cell K+ currents resulting in blunted glucose-stimulated Ca2+ entry and loss of glucose-induced Ca2+ oscillations. Thus, adult Kcnk16 L114P mice have reduced glucose-stimulated insulin secretion and plasma insulin levels, which significantly impairs glucose homeostasis. Taken together, this study shows that the MODY-associated Kcnk16 L114P mutation disrupts glucose homeostasis in adult mice resembling a MODY phenotype and causes neonatal lethality by inhibiting islet insulin secretion during development. These data suggest that TALK-1 is an islet-restricted target for the treatment for diabetes.

Monogenic Diabetes with GATA6 Mutations: Characterization of a Novel Family and a Comprehensive Analysis of the GATA6 Clinical and Genetics Traits

Monogenic diabetes caused by GATA6 mutations were almost described as neonatal diabetes, and the phenotypic spectrum has expanded since then. Our study underscores the broad phenotypic spectrum by reporting a de novo GATA6 mutation in a family. Furthermore, we reviewed related literature to summarize the clinical and genetic characteristics of monogenic diabetes with GATA6 mutations (n = 39) in order to improve clinicians' understanding of the disease. We conclude that the GATA6 missense mutation (c. 749G > T, p. Gly250Val) is not reported presently, characterized by adult-onset diabetes with pancreatic dysplasia and located in transcriptional activation region. Carries with GATA6 mutations (n = 55) have a variable spectrum of diabetes, ranging from neonatal (72.7%), childhood-onset (20%) to adults-onset (7.5%). 83.5% of patients with abnormal pancreatic development. Heart and hepatobillary defects are the most common abnormalities of extrapancreatic features. Most mutations with GATA6 are loss of function (LOF, 71.8%) and located in functional region. Functional studies mostly support loss-of-function as the pathophysiological mechanism. In conclusion, there are various types of diabetes with GATA6 mutations, which can also occur in adult diabetes. Phenotypic defects with GATA6 mutations are most frequently malformations of pancreas and heart. This highlights the importance of comprehensive clinical evaluation of identified carriers to evaluate their full phenotypic spectrum.

A novel mutation in the ABCC8 gene causing maturity-onset diabetes of the young: A case report

A 34-year-old woman was diagnosed with type 1 diabetes mellitus and treated with insulin for 24 years. The patient has a family history of diabetes in three consecutive generations. Her Whole exon sequencing showed a heterozygous mutation in the ABCC8 gene, and it also found some of her relatives to carry this mutation. She was diagnosed with MODY12 and received glimepiride therapy with the achievement of good glycaemic control.

The MODY-associated KCNK16 L114P mutation increases islet glucagon secretion and limits insulin secretion resulting in transient neonatal diabetes and glucose dyshomeostasis in adults

The gain-of-function mutation in the TALK-1 K + channel (p.L114P) is associated with maturity-onset diabetes of the young (MODY). TALK-1 is a key regulator of β-cell electrical activity and glucose-stimulated insulin secretion (GSIS). The KCNK16 gene encoding TALK-1, is the most abundant and β-cell-restricted K + channel transcript. To investigate the impact of KCNK16 L114P on glucose homeostasis and confirm its association with MODY, a mouse model containing the Kcnk16 L114P mutation was generated. Heterozygous and homozygous Kcnk16 L114P mice exhibit increased neonatal lethality in the C57BL/6J and the mixed C57BL/6J:CD-1(ICR) genetic background, respectively. Lethality is likely a result of severe hyperglycemia observed in the homozygous Kcnk16 L114P neonates due to lack of glucose-stimulated insulin secretion and can be reduced with insulin treatment. Kcnk16 L114P increased whole-cell β-cell K + currents resulting in blunted glucose-stimulated Ca 2+ entry and loss of glucose-induced Ca 2+ oscillations. Thus, adult Kcnk16 L114P mice have reduced glucose-stimulated insulin secretion and plasma insulin levels, which significantly impaired glucose homeostasis. Taken together, this study shows that the MODY-associated Kcnk16 L114P mutation disrupts glucose homeostasis in adult mice resembling a MODY phenotype and causes neonatal lethality by inhibiting islet hormone secretion during development. These data strongly suggest that TALK-1 is an islet-restricted target for the treatment of diabetes.

Family History of Type 2 Diabetes and Its Association with Beta Cell Function and Lipid Profile in Newly Diagnosed Pediatric Patients with Type 1 Diabetes

OBJECTIVE

The objective of this study was to explore the associations between a family history of type 2 diabetes (T2D) and beta-cell function, as well as lipid profile, in pediatric patients newly diagnosed with type 1 diabetes (T1D).

METHODS

A retrospective analysis was conducted on children under 14 years of age who were newly diagnosed with T1D at the Children's Hospital of Zhejiang University between August 2018 and August 2022. Clinical features, metabolic profiles, beta-cell function, and lipid profile were evaluated.

RESULTS

A total of 316 children were diagnosed with new-onset T1D. Among them, 28.2% had a family history of T2D. Patients with T1D who had a family history of T2D experienced a later onset of the disease (p = 0.016), improved HOMA2-%B levels (p = 0.003), and increased concentrations of HDL-C (p = 0.005). In addition, no statistically significant differences in age at onset, HOMA2-%B levels, or HDL-C were found when assessing the interaction between family history of T2D and type of diabetes mellitus (autoimmune T1D/idiopathic T1D).

CONCLUSION

A family history of T2D may contribute to the heterogeneity of T1D patients in terms of HOMA2-%B levels and lipid profile. This highlights the significance of taking into account T2D-related factors in the diagnosis and treatment of T1D.

Hepatocyte nuclear factor 1B deletion, but not intragenic mutation, might be more susceptible to hypomagnesemia

AIMS

HNF1B syndrome is caused by defects in the hepatocyte nuclear factor 1B (HNF1B) gene, which leads to maturity-onset diabetes of the young type 5 and congenital organ malformations. This study aimed to identify a gene defect in a patient presenting with diabetes and severe diarrhea, while also analyzing the prevalence of hypomagnesemia and its correlation with the HNF1B genotype.

MATERIALS AND METHODS

Whole exome sequencing was used to identify responsible point mutations and small indels in the proband and their family members. Multiplex ligation-dependent probe amplification was carried out to identify HNF1B deletions. Furthermore, an analysis of published data on 539 cumulative HNF1B cases, from 29 literature sources, was carried out to determine the correlation between the HNF1B genotype and the phenotype of serum magnesium status.

RESULTS

Using multiplex ligation-dependent probe amplification, we identified a de novo heterozygous HNF1B deletion in the patient, who showed dorsal pancreas agenesis and multiple kidney cysts, as detected by magnetic resonance imaging. Magnesium supplementation effectively alleviated the symptoms of diarrhea. Hypomagnesemia was highly prevalent in 192 out of 354 (54.2%) patients with HNF1B syndrome. Compared with patients with intragenic mutations, those with HNF1B deletions were more likely to suffer from hypomagnesemia, with an odds ratio of 3.1 (95% confidence interval 1.8-5.4).

CONCLUSIONS

Hypomagnesemia is highly prevalent in individuals with HNF1B syndrome, and those with HNF1B deletion are more susceptible to developing hypomagnesemia compared with those with intragenic mutations. The genotype-phenotype associations in HNF1B syndrome have significant implications for endocrinologists in terms of genotype detection, treatment decisions and prognosis assessment.

Clinical and genetic characteristics of CEL-MODY (MODY8): a literature review and screening in Chinese individuals diagnosed with early-onset type 2 diabetes

OBJECTIVE

CEL-related maturity-onset diabetes of the young (CEL-MODY, MODY8) is a special type of monogenetic diabetes caused by mutations in the carboxyl-ester lipase (CEL) gene. This study aimed to summarize the genetic and clinical characteristics of CEL-MODY patients and to determine the prevalence of the disease among Chinese patients with early-onset type 2 diabetes (EOD).

METHODS

We systematically reviewed the literature associated with CEL-MODY in PubMed, Embase, Web of Science, China National Knowledge Infrastructure and Wanfang Data to analyze the features of patients with CEL-MODY. We screened and evaluated rare variants of the CEL gene in a cohort of 679 Chinese patients with EOD to estimate the prevalence of CEL-MODY in China.

RESULTS

In total, 21 individuals reported in previous studies were diagnosed with CEL-MODY based on the combination of diabetes and pancreatic exocrine dysfunction as well as frameshift mutations in exon 11 of the CEL gene. CEL-MODY patients were nonobese and presented with exocrine pancreatic affection (e.g., chronic pancreatitis, low fecal elastase levels, pancreas atrophy and lipomatosis) followed by insulin-dependent diabetes. No carriers of CEL missense mutations were reported with exocrine pancreatic dysfunction. Sequencing of CEL in Chinese EOD patients led to the identification of the variant p.Val736Cysfs*22 in two patients. However, these patients could not be diagnosed with CEL-MODY because there were no signs that the exocrine pancreas was afflicted.

CONCLUSION

CEL-MODY is a very rare disease caused by frameshift mutations affecting the proximal VNTR segments of the CEL gene. Signs of exocrine pancreatic dysfunction provide diagnostic clues for CEL-MODY, and genetic testing is vital for proper diagnosis. Further research in larger cohorts is needed to investigate the characteristics and prevalence of CEL-MODY in the Chinese population.

Maturity-onset Diabetes of the Young Type 7 (MODY7) and the Krüppellike Factor 11 Mutation (KLF11). A Review

INTRODUCTION

Maturity-onset diabetes of the young (MODY) is a rare disease due to a single gene mutation that affects several family members in most cases. The Krüppel-like factor 11 (KLF11) gene mutation is associated with decreased insulin sensitivity to high glucose levels. KLF 11 has been implicated in the pathogenesis of MODY type 7 but given its low prevalence, prolonged subclinical period, and the emergence of new information, doubts are raised about its association.

METHODS

A literature search of the PubMed, Scopus, and EBSCO databases was performed. The terms "Diabetes Mellitus, Type 2/genetics", "Mason-Type Diabetes" , "Maturity-Onset diabetes of the young", "KLF11 protein, human", and "Maturity-Onset Diabetes of the Young, Type 7" were used"., "Diagnosis" The search selection was not standardized.

RESULTS

The KLF1 mutation is rare and represents <1% of the mutations associated with monogenic diabetes. Its isolation in European family lines in the first studies and the emergence of new variants pose new diagnostic challenges. This article reviews the definition, epidemiology, pathophysiology, diagnosis, and treatment of MODY type 7.

CONCLUSION

MODY type 7 diabetes represents a rare form of monogenic diabetes with incomplete penetrance. Given its rarity, its association with impaired glucose metabolism has been questioned. Strict evaluation of glycemic control and the appearance of microvascular complications are key areas in the follow-up of patients diagnosed with MODY 7. More studies will be required to characterize the population with KLF11 mutation and clarify its correlation with MODY.

American Diabetes Association Professional Practice Committee, ElSayed NA, Aleppo G, Bannuru RR, Bruemmer D, Collins BS, Ekhlaspour L, Gaglia JL, Hilliard ME, Johnson EL, Khunti K, Lingvay I, Matfin G, McCoy RG, Perry ML, Pilla SJ, Polsky S, Prahalad P, Pratley RE, Segal AR, Seley JJ, Selvin E, Stanton RC, Gabbay RA. 2. Diagnosis and Classification of Diabetes: Standards of Care in Diabetes-2024

The American Diabetes Association (ADA) "Standards of Care in Diabetes" includes the ADA's current clinical practice recommendations and is intended to provide the components of diabetes care, general treatment goals and guidelines, and tools to evaluate quality of care. Members of the ADA Professional Practice Committee, an interprofessional expert committee, are responsible for updating the Standards of Care annually, or more frequently as warranted. For a detailed description of ADA standards, statements, and reports, as well as the evidence-grading system for ADA's clinical practice recommendations and a full list of Professional Practice Committee members, please refer to Introduction and Methodology. Readers who wish to comment on the Standards of Care are invited to do so at professional.diabetes.org/SOC.

Genetic perspectives on childhood monogenic diabetes: Diagnosis, management, and future directions

Monogenic diabetes is caused by one or even more genetic variations, which may be uncommon yet have a significant influence and cause diabetes at an early age. Monogenic diabetes affects 1 to 5% of children, and early detection and gene-tically focused treatment of neonatal diabetes and maturity-onset diabetes of the young can significantly improve long-term health and well-being. The etiology of monogenic diabetes in childhood is primarily attributed to genetic variations affecting the regulatory genes responsible for beta-cell activity. In rare instances, mutations leading to severe insulin resistance can also result in the development of diabetes. Individuals diagnosed with specific types of monogenic diabetes, which are commonly found, can transition from insulin therapy to sulfonylureas, provided they maintain consistent regulation of their blood glucose levels. Scientists have successfully devised materials and methodologies to distinguish individuals with type 1 or 2 diabetes from those more prone to monogenic diabetes. Genetic screening with appropriate findings and interpretations is essential to establish a prognosis and to guide the choice of therapies and management of these interrelated ailments. This review aims to design a comprehensive literature summarizing genetic insights into monogenetic diabetes in children and adolescents as well as summarizing their diagnosis and mana-gement.

Whole-exome sequencing reveals novel variants of monogenic diabetes in Tunisia: impact on diagnosis and healthcare management

Introduction: Monogenic diabetes (MD) accounts for 3%-6% of all cases of diabetes. This prevalence is underestimated due to its overlapping clinical features with type 1 and type 2 diabetes. Hence, genetic testing is the most appropriate tool for obtaining an accurate diagnosis. In Tunisia, few cohorts of MD have been investigated until now. The aim of this study is to search for pathogenic variants among 11 patients suspected of having MD in Tunisia using whole-exome sequencing (WES). Materials and methods: WES was performed in 11 diabetic patients recruited from a collaborating medical center. The pathogenicity of genetic variation was assessed using combined filtering and bioinformatics prediction tools. The online ORVAL tool was used to predict the likelihood of combinations of pathogenic variations. Then, Sanger sequencing was carried out to confirm likely pathogenic predicted variants among patients and to check for familial segregation. Finally, for some variants, we performed structural modeling to study their impact on protein function. Results: We identified novel variants related to MD in Tunisia. Pathogenic variants are located in several MODY and non-MODY genes. We highlighted the presence of syndromic forms of diabetes, including the Bardet-Biedl syndrome, Alström syndrome, and severe insulin resistance, as well as the presence of isolated diabetes with significantly reduced penetrance for Wolfram syndrome-related features. Idiopathic type 1 diabetes was also identified in one patient. Conclusion: In this study, we emphasized the importance of genetic screening for MD in patients with a familial history of diabetes, mainly among admixed and under-represented populations living in low- and middle-income countries. An accurate diagnosis with molecular investigation of MD may improve the therapeutic choice for better management of patients and their families. Additional research and rigorous investigations are required to better understand the physiopathological mechanisms of MD and implement efficient therapies that take into account genomic context and other related factors.

The challenges of identifying and studying type 1 diabetes in adults

Diagnosing type 1 diabetes in adults is difficult since type 2 diabetes is the predominant diabetes type, particularly with an older age of onset (approximately >30 years). Misclassification of type 1 diabetes in adults is therefore common and will impact both individual patient management and the reported features of clinically classified cohorts. In this article, we discuss the challenges associated with correctly identifying adult-onset type 1 diabetes and the implications of these challenges for clinical practice and research. We discuss how many of the reported differences in the characteristics of autoimmune/type 1 diabetes with increasing age of diagnosis are likely explained by the inadvertent study of mixed populations with and without autoimmune aetiology diabetes. We show that when type 1 diabetes is defined by high-specificity methods, clinical presentation, islet-autoantibody positivity, genetic predisposition and progression of C-peptide loss remain broadly similar and severe at all ages and are unaffected by onset age within adults. Recent clinical guidance recommends routine islet-autoantibody testing when type 1 diabetes is clinically suspected or in the context of rapid progression to insulin therapy after a diagnosis of type 2 diabetes. In this moderate or high prior-probability setting, a positive islet-autoantibody test will usually confirm autoimmune aetiology (type 1 diabetes). We argue that islet-autoantibody testing of those with apparent type 2 diabetes should not be routinely undertaken as, in this low prior-prevalence setting, the positive predictive value of a single-positive islet antibody for autoimmune aetiology diabetes will be modest. When studying diabetes, extremely high-specificity approaches are needed to identify autoimmune diabetes in adults, with the optimal approach depending on the research question. We believe that until these recommendations are widely adopted by researchers, the true phenotype of late-onset type 1 diabetes will remain largely misunderstood.

Characterisation of HNF1A variants in paediatric diabetes in Norway using functional and clinical investigations to unmask phenotype and monogenic diabetes

AIMS/HYPOTHESIS

Correctly diagnosing MODY is important, as individuals with this diagnosis can discontinue insulin injections; however, many people are misdiagnosed. We aimed to develop a robust approach for determining the pathogenicity of variants of uncertain significance in hepatocyte nuclear factor-1 alpha (HNF1A)-MODY and to obtain an accurate estimate of the prevalence of HNF1A-MODY in paediatric cases of diabetes.

METHODS

We extended our previous screening of the Norwegian Childhood Diabetes Registry by 830 additional samples and comprehensively genotyped HNF1A variants in autoantibody-negative participants using next-generation sequencing. Carriers of pathogenic variants were treated by local healthcare providers, and participants with novel likely pathogenic variants and variants of uncertain significance were enrolled in an investigator-initiated, non-randomised, open-label pilot study (ClinicalTrials.gov registration no. NCT04239586). To identify variants associated with HNF1A-MODY, we functionally characterised their pathogenicity and assessed the carriers' phenotype and treatment response to sulfonylurea.

RESULTS

In total, 615 autoantibody-negative participants among 4712 cases of paediatric diabetes underwent genetic sequencing, revealing 19 with HNF1A variants. We identified nine carriers with novel variants classified as variants of uncertain significance or likely to be pathogenic, while the remaining ten participants carried five pathogenic variants previously reported. Of the nine carriers with novel variants, six responded favourably to sulfonylurea. Functional investigations revealed their variants to be dysfunctional and demonstrated a correlation with the resulting phenotype, providing evidence for reclassifying these variants as pathogenic.

CONCLUSIONS/INTERPRETATION

Based on this robust classification, we estimate that the prevalence of HNF1A-MODY is 0.3% in paediatric diabetes. Clinical phenotyping is challenging and functional investigations provide a strong complementary line of evidence. We demonstrate here that combining clinical phenotyping with functional protein studies provides a powerful tool to obtain a precise diagnosis of HNF1A-MODY.

Novel pathogenic PDX1 gene variant in a Korean family with maturity-onset diabetes of the young

The diagnosis of maturity-onset diabetes of the young (MODY), a monogenic form of diabetes mellitus caused by a mutation in a single gene, is often uncertain until genetic testing is performed. We report a 13-yr-old Korean boy who was initially diagnosed with type 2 diabetes (T2DM). MODY was suspected because of his nonobese body habitus and family history of multiple affected members. Targeted panel sequencing of all MODY-related genes was performed using the NextSeq 550Dx platform (Illumina). Sanger sequencing was performed using blood samples from the parents, siblings, and other relatives. A frameshift variant in the 3' region of the last exon of PDX1 was detected in the patient and his family members with diabetes. PP1_Moderate criterion was applied and this variant was confirmed to be the genetic cause of diabetes in the family and classified as likely pathogenic. The study highlights the importance of genetic testing for nonobese, early-onset diabetic patients with multiple affected family members. Increased awareness and aggressive genetic testing for MODY are needed.

Precision Medicine in Type 2 Diabetes Mellitus: Utility and Limitations

Type 2 diabetes mellitus (T2DM) is one of the most widespread diseases in Western countries, and its incidence is constantly increasing. Epidemiological studies have shown that in the next 20 years. The number of subjects affected by T2DM will double. In recent years, owing to the development and improvement in methods for studying the genome, several authors have evaluated the association between monogenic or polygenic genetic alterations and the development of metabolic diseases and complications. In addition, sedentary lifestyle and socio-economic and pandemic factors have a great impact on the habits of the population and have significantly contributed to the increase in the incidence of metabolic disorders, obesity, T2DM, metabolic syndrome, and liver steatosis. Moreover, patients with type 2 diabetes appear to respond to antihyperglycemic drugs. Only a minority of patients could be considered true non-responders. Thus, it appears clear that the main aim of precision medicine in T2DM is to identify patients who can benefit most from a specific drug class more than from the others. Precision medicine is a discipline that evaluates the applicability of genetic, lifestyle, and environmental factors to disease development. In particular, it evaluated whether these factors could affect the development of diseases and their complications, response to diet, lifestyle, and use of drugs. Thus, the objective is to find prevention models aimed at reducing the incidence of pathology and mortality and therapeutic personalized approaches, to obtain a greater probability of response and efficacy. This review aims to evaluate the applicability of precision medicine for T2DM, a healthcare burden in many countries.

Skeletal Health in Patients With Mitochondrial Diabetes: Case Series and Review of Literature

Monogenic diabetes, including mitochondrial diabetes, constitutes 1% to 3% of all diabetes. Although there is an increased interest in understanding the mechanisms of bone fragility in people with diabetes, skeletal research is mostly focused on type 1 and type 2 diabetes. Little is known on skeletal health among people with mitochondrial diabetes. In this single-center study, we presented clinical characteristics of individuals with mitochondrial diabetes and clinical diagnosis of osteoporosis. Of 10 patients with mitochondrial diabetes, 4 (40%) had a clinical diagnosis of osteoporosis. Patients with osteoporosis were older, had lower body mass index, longer diabetes duration, lower fasting C-peptide, and presence of multiple comorbidities compared with patients without osteoporosis. In addition to our cases, we also systematically reviewed literature on skeletal health in people with mitochondrial diabetes and provided an overview of potential factors affecting skeletal health and future clinical and research directions to improve the care of people with mitochondrial disease. © 2023 The Authors. JBMR Plus published by Wiley Periodicals LLC on behalf of American Society for Bone and Mineral Research.

The use of precision diagnostics for monogenic diabetes: a systematic review and expert opinion

BACKGROUND

Monogenic diabetes presents opportunities for precision medicine but is underdiagnosed. This review systematically assessed the evidence for (1) clinical criteria and (2) methods for genetic testing for monogenic diabetes, summarized resources for (3) considering a gene or (4) variant as causal for monogenic diabetes, provided expert recommendations for (5) reporting of results; and reviewed (6) next steps after monogenic diabetes diagnosis and (7) challenges in precision medicine field.

METHODS

Pubmed and Embase databases were searched (1990-2022) using inclusion/exclusion criteria for studies that sequenced one or more monogenic diabetes genes in at least 100 probands (Question 1), evaluated a non-obsolete genetic testing method to diagnose monogenic diabetes (Question 2). The risk of bias was assessed using the revised QUADAS-2 tool. Existing guidelines were summarized for questions 3-5, and review of studies for questions 6-7, supplemented by expert recommendations. Results were summarized in tables and informed recommendations for clinical practice.

RESULTS

There are 100, 32, 36, and 14 studies included for questions 1, 2, 6, and 7 respectively. On this basis, four recommendations for who to test and five on how to test for monogenic diabetes are provided. Existing guidelines for variant curation and gene-disease validity curation are summarized. Reporting by gene names is recommended as an alternative to the term MODY. Key steps after making a genetic diagnosis and major gaps in our current knowledge are highlighted.

CONCLUSIONS

We provide a synthesis of current evidence and expert opinion on how to use precision diagnostics to identify individuals with monogenic diabetes.

Maturity-onset diabetes of the young type 9 or latent autoimmune diabetes in adults: A case report and review of literature

BACKGROUND

Maturity-onset diabetes of the young (MODY) is a monogenic genetic disease often clinically misdiagnosed as type 1 or type 2 diabetes. MODY type 9 (MODY9) is a rare subtype caused by mutations in the PAX4 gene. Currently, there are limited reports on PAX4-MODY, and its clinical characteristics and treatments are still unclear. In this report, we described a Chinese patient with high autoimmune antibodies, hyperglycemia and a site mutation in the PAX4 gene.

CASE SUMMARY

A 42-year-old obese woman suffered diabetes ketoacidosis after consuming substantial amounts of beverages. She had never had diabetes before, and no one in her family had it. However, her autoantibody tested positive, and she managed her blood glucose within the normal range for 6 mo through lifestyle inter-ventions. Later, her blood glucose gradually increased. Next-generation sequencing and Sanger sequencing were performed on her family. The results revealed that she and her mother had a heterozygous mutation in the PAX4 gene (c.314G>A, p.R105H), but her daughter did not. The patient is currently taking liraglutide (1.8 mg/d), and her blood glucose levels are under control. Previous cases were retrieved from PubMed to investigate the relationship between PAX4 gene mutations and diabetes.

CONCLUSION

We reported the first case of a PAX4 gene heterozygous mutation site (c.314G>A, p.R105H), which does not appear pathogenic to MODY9 but may facilitate the progression of latent autoimmune diabetes in adults.

Implementation of genomic medicine for rare disease in a tertiary healthcare system: Mayo Clinic Program for Rare and Undiagnosed Diseases (PRaUD)

BACKGROUND

In the United States, rare disease (RD) is defined as a condition that affects fewer than 200,000 individuals. Collectively, RD affects an estimated 30 million Americans. A significant portion of RD has an underlying genetic cause; however, this may go undiagnosed. To better serve these patients, the Mayo Clinic Program for Rare and Undiagnosed Diseases (PRaUD) was created under the auspices of the Center for Individualized Medicine (CIM) aiming to integrate genomics into subspecialty practice including targeted genetic testing, research, and education.

METHODS

Patients were identified by subspecialty healthcare providers from 11 clinical divisions/departments. Targeted multi-gene panels or custom exome/genome-based panels were utilized. To support the goals of PRaUD, a new clinical service model, the Genetic Testing and Counseling (GTAC) unit, was established to improve access and increase efficiency for genetic test facilitation. The GTAC unit includes genetic counselors, genetic counseling assistants, genetic nurses, and a medical geneticist. Patients receive abbreviated point-of-care genetic counseling and testing through a partnership with subspecialty providers.

RESULTS

Implementation of PRaUD began in 2018 and GTAC unit launched in 2020 to support program expansion. Currently, 29 RD clinical indications are included in 11 specialty divisions/departments with over 142 referring providers. To date, 1152 patients have been evaluated with an overall solved or likely solved rate of 17.5% and as high as 66.7% depending on the phenotype. Noteworthy, 42.7% of the solved or likely solved patients underwent changes in medical management and outcome based on genetic test results.

CONCLUSION

Implementation of PRaUD and GTAC have enabled subspecialty practices advance expertise in RD where genetic counselors have not historically been embedded in practice. Democratizing access to genetic testing and counseling can broaden the reach of patients with RD and increase the diagnostic yield of such indications leading to better medical management as well as expanding research opportunities.

Next Generation Sequencing (NGS) Target Approach for Undiagnosed Dysglycaemia

Next-generation sequencing (NGS) has revolutionized the field of genomics and created new opportunities for basic research. We described the strategy for the NGS validation of the "dysglycaemia panel" composed by 44 genes related to glucose metabolism disorders (MODY, Wolfram syndrome) and familial renal glycosuria using Ion AmpliSeq technology combined with Ion-PGM. Anonymized DNA of 32 previously genotyped cases with 33 different variants were used to optimize the methodology. Standard protocol was used to generate the primer design, library, template preparation, and sequencing. Ion Reporter tool was used for data analysis. In all the runs, the mean coverage was over 200×. Twenty-nine out of thirty three variants (96.5%) were detected; four frameshift variants were missed. All point mutations were detected with high sensitivity. We identified three further variants of unknown significance in addition to pathogenic mutations previously identified by Sanger sequencing. The NGS panel allowed us to identify pathogenic variants in multiple genes in a short time. This could help to identify several defects in children and young adults that have to receive the genetic diagnosis necessary for optimal treatment. In order not to lose any pathogenic variants, Sanger sequencing is included in our analytical protocol to avoid missing frameshift variants.

A Systematic Review of the use of Precision Diagnostics in Monogenic Diabetes

Monogenic forms of diabetes present opportunities for precision medicine as identification of the underlying genetic cause has implications for treatment and prognosis. However, genetic testing remains inconsistent across countries and health providers, often resulting in both missed diagnosis and misclassification of diabetes type. One of the barriers to deploying genetic testing is uncertainty over whom to test as the clinical features for monogenic diabetes overlap with those for both type 1 and type 2 diabetes. In this review, we perform a systematic evaluation of the evidence for the clinical and biochemical criteria used to guide selection of individuals with diabetes for genetic testing and review the evidence for the optimal methods for variant detection in genes involved in monogenic diabetes. In parallel we revisit the current clinical guidelines for genetic testing for monogenic diabetes and provide expert opinion on the interpretation and reporting of genetic tests. We provide a series of recommendations for the field informed by our systematic review, synthesizing evidence, and expert opinion. Finally, we identify major challenges for the field and highlight areas for future research and investment to support wider implementation of precision diagnostics for monogenic diabetes.

Diagnosis, treatment and disclosure: A qualitative exploration of participant challenges in a Monogenic Diabetes Registry

PURPOSE

Maturity-onset diabetes of the young (MODY) represents a heterogenous group of monogenic diabetes. Despite its autosomal dominant inheritance, many MODY participants in the University of Chicago Monogenic Diabetes Registry have no family members enrolled. We aimed to gather data on the Registry participants' experiences in (1) receipt of an accurate diagnosis, (2) decisions regarding disclosure of their MODY genetic test results with biological relatives, and (3) recommendations toward our Registry's processes and outreach.

METHODS

We conducted 20 one-on-one semistructured interviews with adult Registry participants.

RESULTS

All participants found navigating the health care system challenging because of the providers' unfamiliarity with MODY and dismissal of its importance post diagnosis. All had shared their results with at least 1 relative, however many found their relatives resistant to engaging with their providers. Participants wanted to receive targeted information on their condition and connect with other participants who have faced similar diagnostic and treatment challenges.

CONCLUSION

Our results demonstrate that our probands faced resistance to reclassification of their diabetes from both health care providers and relatives. In an effort to improve cascade testing, the Registry is designing a portal to facilitate participant-research team communication and provide additional supports for participants to involve family members in testing.

Monogenic diabetes

Monogenic diabetes includes several clinical conditions generally characterized by early-onset diabetes, such as neonatal diabetes, maturity-onset diabetes of the young (MODY) and various diabetes-associated syndromes. However, patients with apparent type 2 diabetes mellitus may actually have monogenic diabetes. Indeed, the same monogenic diabetes gene can contribute to different forms of diabetes with early or late onset, depending on the functional impact of the variant, and the same pathogenic variant can produce variable diabetes phenotypes, even in the same family. Monogenic diabetes is mostly caused by impaired function or development of pancreatic islets, with defective insulin secretion in the absence of obesity. The most prevalent form of monogenic diabetes is MODY, which may account for 0.5-5% of patients diagnosed with non-autoimmune diabetes but is probably underdiagnosed owing to insufficient genetic testing. Most patients with neonatal diabetes or MODY have autosomal dominant diabetes. More than 40 subtypes of monogenic diabetes have been identified to date, the most prevalent being deficiencies of GCK and HNF1A. Precision medicine approaches (including specific treatments for hyperglycaemia, monitoring associated extra-pancreatic phenotypes and/or following up clinical trajectories, especially during pregnancy) are available for some forms of monogenic diabetes (including GCK- and HNF1A-diabetes) and increase patients' quality of life. Next-generation sequencing has made genetic diagnosis affordable, enabling effective genomic medicine in monogenic diabetes.

Identification of monogenic variants in more than ten per cent of children without type 1 diabetes-related autoantibodies at diagnosis in the Finnish Pediatric Diabetes Register

AIMS/HYPOTHESIS

Monogenic forms of diabetes (MODY, neonatal diabetes mellitus and syndromic forms) are rare, and affected individuals may be misclassified and treated suboptimally. The prevalence of type 1 diabetes is high in Finnish children but systematic screening for monogenic diabetes has not been conducted. We assessed the prevalence and clinical manifestations of monogenic diabetes in children initially registered with type 1 diabetes in the Finnish Pediatric Diabetes Register (FPDR) but who had no type 1 diabetes-related autoantibodies (AABs) or had only low-titre islet cell autoantibodies (ICAs) at diagnosis.

METHODS

The FPDR, covering approximately 90% of newly diagnosed diabetic individuals aged ≤15 years in Finland starting from 2002, includes data on diabetes-associated HLA genotypes and AAB data (ICA, and autoantibodies against insulin, GAD, islet antigen 2 and zinc transporter 8) at diagnosis. A next generation sequencing gene panel including 42 genes was used to identify monogenic diabetes. We interpreted the variants in HNF1A by using the gene-specific standardised criteria and reported pathogenic and likely pathogenic findings only. For other genes, we also reported variants of unknown significance if an individual's phenotype suggested monogenic diabetes.

RESULTS

Out of 6482 participants, we sequenced DNA for 152 (2.3%) testing negative for all AABs and 49 (0.8%) positive only for low-titre ICAs (ICA_low). A monogenic form of diabetes was revealed in 19 (12.5%) of the AAB-negative patients (14 [9.2%] had pathogenic or likely pathogenic variants) and two (4.1%) of the ICA_low group. None had ketoacidosis at diagnosis or carried HLA genotypes conferring high risk for type 1 diabetes. The affected genes were GCK, HNF1A, HNF4A, HNF1B, INS, KCNJ11, RFX6, LMNA and WFS1. A switch from insulin to oral medication was successful in four of five patients with variants in HNF1A, HNF4A or KCNJ11.

CONCLUSIONS/INTERPRETATION

More than 10% of AAB-negative children with newly diagnosed diabetes had a genetic finding associated with monogenic diabetes. Because the genetic diagnosis can lead to major changes in treatment, we recommend referring all AAB-negative paediatric patients with diabetes for genetic testing. Low-titre ICAs in the absence of other AABs does not always indicate a diagnosis of type 1 diabetes.

Prevalence and characteristics of misdiagnosed adult-onset type 1 diabetes mellitus in Thai people by random plasma C-peptide testing

Background

It is critical to determine the exact type of diabetes because misclassification led to inappropriate treatments. The classification of DM can be aided by the measurement of pancreatic autoantibodies and plasma C-peptide levels. Previous studies suggested that random plasma C-peptide testing in those with clinically diagnosed adult T1DM of at least 3 years duration has led to reclassification in some cases.

Aim

This study aimed to assess the prevalence and characteristics of misdiagnosed adult-onset type 1 diabetes mellitus in Thai people by random plasma C-peptide testing.

Methods

A cross-sectional study of adult Thai patients diagnosed with clinically diagnosed T1DM and DM duration of at least 3 years at Theptarin Hospital, a diabetes center in Bangkok, Thailand was studied. Clinically misdiagnosis of T1DM was defined by preserved endogenous insulin secretion. Characteristics of the misdiagnosed patients were compared with definite T1DM patients.

Results

A total of 73 patients (females 52.1%, mean age 42.2 ± 12.5 years, duration of DM 20.3 ± 11.3 years) were studied. The prevalence of available anti-GAD and anti-IA2 were 53.3% and 20.8%, respectively. Preserved endogenous insulin secretion evaluated by random C-peptide or stimulated C-peptide was found in 8 patients (11.0%). The misdiagnosed patients had higher prevalence of hypertension and diabetic complications. Three patients were suspected to have monogenic diabetes and five patients were reclassified as possible T2DM.

Conclusions

Approximately one-tenth of adult T1DM patients were misdiagnosed. Random plasma C-peptide testing at least 3 years after a diagnosis of T1DM was superior to the measurement of pancreatic autoantibodies. Our present study highlights the need to increase accuracy in the diagnosis of T1DM patients by re-assessing endogenous insulin production with measurement of random plasma C-peptide levels.

Genetic and Functional Analyses of the Novel KLF11 Pro193Thr Variant in a Three-Generation Family with MODY7

KLF11 regulates insulin gene expression through binding to the insulin promoter and has been reported as a causative gene for maturity-onset diabetes of the young 7 (MODY7). Here, we report a novel KLF11 variant associated with a three-generation family with early childhood-onset diabetes and explore its clinical and functional characteristics. The three-generational pedigree contains five patients affected by diabetes. The pathogenic variant identified by whole-exome sequencing was further confirmed by Sanger sequencing and pedigree verification. Luciferase reporter assays and glucose-stimulated insulin secretion were used to examine whether the KLF11 variant binds to the insulin promoter and regulate insulin secretion in vitro. The proband, his son, and his uncle exhibited hyperglycemia at ages 32, 13 and 71 years, respectively. All three patients showed characteristics of metabolic syndrome (obesity, dyslipidemia, and diabetes), but the insulin secretion of islet β-cells was impaired. A novel heterozygous missense variant, c.577 C>A (p.Pro193Thr) of the KLF11 gene was detected in all three patients. This variant co-segregates with the diabetes phenotype, consistent with an autosomal dominant disorder. The identified KLF11 p.Pro193Thr variant drastically decreased the transcriptional activity of KLF11, as demonstrated by luciferase reporter assay. Functional analyses revealed that the KLF11 Pro193Thr variant inhibited glucose-stimulated insulin secretion. We identified a novel KLF11 Pro193Thr variant in a three generation family with MODY7. These findings shed light on the molecular mechanisms underlying the pathogenesis of MODY7 and expand the genotype and clinical spectrum of MODY7.

Prevalence of maturity-onset diabetes of the young in phenotypic type 2 diabetes in young adults: a nationwide, multi-center, cross-sectional survey in China

BACKGROUND

Maturity-onset diabetes of the young (MODY) is the most common monogenic diabetes. The aim of this study was to assess the prevalence of MODY in phenotypic type 2 diabetes (T2DM) among Chinese young adults.

METHODS

From April 2015 to October 2017, this cross-sectional study involved 2429 consecutive patients from 46 hospitals in China, newly diagnosed between 15 years and 45 years, with T2DM phenotype and negative for standardized glutamic acid decarboxylase antibody at the core laboratory. Sequencing using a custom monogenic diabetes gene panel was performed, and variants of 14 MODY genes were interpreted as per current guidelines.

RESULTS

The survey determined 18 patients having genetic variants causing MODY (6 HNF1A , 5 GCK , 3 HNF4A , 2 INS , 1 PDX1 , and 1 PAX4 ). The prevalence of MODY was 0.74% (95% confidence interval [CI]: 0.40-1.08%). The clinical characteristics of MODY patients were not specific, 72.2% (13/18) of them were diagnosed after 35 years, 47.1% (8/17) had metabolic syndrome, and only 38.9% (7/18) had a family history of diabetes. No significant difference in manifestations except for hemoglobin A1c levels was found between MODY and non-MODY patients.

CONCLUSION

The prevalence of MODY in young adults with phenotypic T2DM was 0.74%, among which HNF1A -, GCK -, and HNF4A -MODY were the most common subtypes. Clinical features played a limited role in the recognition of MODY.

2. Classification and Diagnosis of Diabetes: Standards of Care in Diabetes-2023

The American Diabetes Association (ADA) "Standards of Care in Diabetes" includes the ADA's current clinical practice recommendations and is intended to provide the components of diabetes care, general treatment goals and guidelines, and tools to evaluate quality of care. Members of the ADA Professional Practice Committee, a multidisciplinary expert committee, are responsible for updating the Standards of Care annually, or more frequently as warranted. For a detailed description of ADA standards, statements, and reports, as well as the evidence-grading system for ADA's clinical practice recommendations and a full list of Professional Practice Committee members, please refer to Introduction and Methodology. Readers who wish to comment on the Standards of Care are invited to do so at professional.diabetes.org/SOC.

[Other specific types of diabetes and exocrine pancreatic insufficiency (update 2023)]

The heterogenous category "specific types of diabetes due to other causes" encompasses disturbances in glucose metabolism due to other endocrine disorders such as acromegaly or hypercortisolism, drug-induced diabetes (e.g. antipsychotic medications, glucocorticoids, immunosuppressive agents, highly active antiretroviral therapy (HAART), checkpoint inhibitors), genetic forms of diabetes (e.g. Maturity Onset Diabetes of the Young (MODY), neonatal diabetes, Down‑, Klinefelter- and Turner Syndrome), pancreatogenic diabetes (e.g. postoperatively, pancreatitis, pancreatic cancer, haemochromatosis, cystic fibrosis), and some rare autoimmune or infectious forms of diabetes. Diagnosis of specific diabetes types might influence therapeutic considerations. Exocrine pancreatic insufficiency is not only found in patients with pancreatogenic diabetes but is also frequently seen in type 1 and long-standing type 2 diabetes.