SARS-CoV-2 molecular epidemiology in Slovenia, January to September 2021.

BackgroundSequencing of SARS-CoV-2 PCR-positive samples was introduced in Slovenia in January 2021. Our surveillance programme comprised three complementary schemes: (A) non-targeted sequencing of at least 10% of samples, (B) sequencing of samples positive after PCR screening for variants of concern (VOC) and (C) sequencing as per epidemiological indication.AimWe present the analysis of cumulative data of the non-targeted surveillance of SARS-CoV-2 and variant-dependent growth kinetics for the five most common variants in Slovenia for the first 9 months of 2021.MethodsSARS-CoV-2 PCR-positive samples, from January to September 2021, were selected for sequencing according to the national surveillance plan. Growth kinetics studies were done on Vero E6 cells.ResultsAltogether 15,175 genomes were sequenced and 64 variants were detected, of which three successively prevailed. Variant B.1.258.17 was detected in ca 80% of samples in January and was replaced, within 9 weeks, by the Alpha variant. The number of cases decreased substantially during the summer of 2021. However, the introduction of the Delta variant caused a fourth wave and completely outcompeted other variants. Other VOC were only detected in small numbers. Infection of Vero E6 cells showed higher replication rates for the variants Alpha and Delta, compared with B.1.258.17, B.1.258, and B.1.1.70, which dominated in Slovenia before the introduction of the Alpha and Delta variants.ConclusionInformation on SARS-CoV-2 variant diversity provided context to the epidemiological data of PCR-positive cases, contributed to control of the initial spread of known VOC and influenced epidemiological measures.

Contribution of Retrotransposons to the Pathogenesis of Type 1 Diabetes and Challenges in Analysis Methods.

Type 1 diabetes (T1D) is one of the most common chronic diseases of the endocrine system, associated with several life-threatening comorbidities. While the etiopathogenesis of T1D remains elusive, a combination of genetic susceptibility and environmental factors, such as microbial infections, are thought to be involved in the development of the disease. The prime model for studying the genetic component of T1D predisposition encompasses polymorphisms within the HLA (human leukocyte antigen) region responsible for the specificity of antigen presentation to lymphocytes. Apart from polymorphisms, genomic reorganization caused by repeat elements and endogenous viral elements (EVEs) might be involved in T1D predisposition. Such elements are human endogenous retroviruses (HERVs) and non-long terminal repeat (non-LTR) retrotransposons, including long and short interspersed nuclear elements (LINEs and SINEs). In line with their parasitic origin and selfish behaviour, retrotransposon-imposed gene regulation is a major source of genetic variation and instability in the human genome, and may represent the missing link between genetic susceptibility and environmental factors long thought to contribute to T1D onset. Autoreactive immune cell subtypes with differentially expressed retrotransposons can be identified with single-cell transcriptomics, and personalized assembled genomes can be constructed, which can then serve as a reference for predicting retrotransposon integration/restriction sites. Here we review what is known to date about retrotransposons, we discuss the involvement of viruses and retrotransposons in T1D predisposition, and finally we consider challenges in retrotransposons analysis methods.

Universal screening for familial hypercholesterolemia in 2 populations.

PURPOSE: In Europe, >2 million individuals with familial hypercholesterolemia (FH) are currently undiagnosed. Effective screening strategies for FH diagnosis in childhood are urgently needed. We assessed the overall performances of 2 different FH screening programs in children: universal screening program with opt-out and opt-in type participation. METHODS: We analyzed the data from 2 independent populations based on >166,000 individuals screened for hypercholesterolemia. Genetic analyses of FH-related genes were finalized in 945 children and 99 parents. RESULTS: A total of 305 (32.3%) children were genotyped as positive or with a variant of uncertain significance in FH-related genes. For low-density lipoprotein cholesterol levels of 3.5 mmol L (135.3 mg/dL), the overall sensitivity and specificity for confirming FH were 90.5% and 55.3%, respectively. As part of child-parent screening, in >90% of the families, the parent with reported higher cholesterol levels was positive for the familial genetic variant. The cohort-based prevalence of FH from the opt-out universal screening program was estimated to be 1 in 431 individuals (95% CI = 1/391-1/472). CONCLUSION: Universal 3-step FH screening approach in children enabled detection of most children and their parents in every generation screened at reasonable costs. Opt-out screening strategy might be preferable over opt-in screening strategy.

Rezidivierende fulminante Myokarditis mit wiederholtem Einsatz der ECMO bei einem Kind.

Recurrent myocarditis is rare with only few reports having been published for paediatric cases. Repeated use of extracorporeal membrane oxygenation is also uncommon. In this paper we will present a very rare case of a 7-year old girl with recurrent fulminant myocarditis with heart failure requiring cardiopulmonary resuscitation and mechanical circulatory support with extracorporeal membrane oxygenation. Both episodes were precipitated by a viral upper respiratory tract infection, and in both cases the cardiac function eventually completely recovered. The second episode of fulminant myocarditis was particularly complex with markedly elevated markers of myocardiocytolysis, multiorgan dysfunction and the need for prolonged mechanical circulatory support. Nevertheless, the patient made a remarkable recovery. A comprehensive diagnostic workup pointed towards an aberrant immune response as the likely cause of the girl's susceptibility for fulminant myocarditis.

DEPTOR promoter genetic variants and insulin resistance in obese children and adolescents.

BACKGROUND: Insulin resistance (IR) is one of the major metabolic complications of obesity in children and adolescents. DEP domain-containing mammalian target of rapamycin interacting protein (DEPTOR) is involved in downstream insulin signaling and DEPTOR's effects are regulated by its level of expression. OBJECTIVES: To analyze promoter region of DEPTOR for genetic variants associated with altered IR in obese children and adolescents. SUBJECTS AND METHODS: IR was determined in 322 normoglycemic obese subjects [173 females, 149 males; mean age 13.3 ± 3.5 yr, mean BMI-SDS 2.85 ± 0.83, HbA1C 5.2 ± 0.2% (33 ± 2.5 mmol/mol)] using homeostatic model assessment - insulin resistance [HOMA-IR (>2 prepubertal and >3 pubertal)] and whole body insulin sensitivity index [WBISI (<6.5 prepubertal and <4.5 pubertal)]. Genetic variants, determined by high resolution melting analysis, were confirmed by Sanger sequencing, whereas population allele distribution was determined by TaqMan genotyping probes. RESULTS: Genetic variant c.-143T>C (rs7840156) was associated with a significant 2-fold decreased risk to present with IR, determined by HOMA-IR [odds ratio (OR) = 0.614, 95% confidence interval (CI) = 0.435-0.867, p = 0.0057) and WBISI (OR = 0.582, 95% CI = 0.414-0.817, p = 0.0018). The CC genotype had lower mean HOMA-IR value (2.47 ± 0.44 vs. 3.04 ± 0.14, p = 0.0177) and higher mean WBISI value (7.00 ± 0.71 vs. 5.27 ± 0.33, p = 0.0235) than TT genotype. Variant c.-143T>C was located in evolutionary highly conserved region in DEPTOR promoter region. CONCLUSION: Presented results on association between insulin sensitivity and genetic variants in DEPTOR gene suggest DEPTOR and mammalian target of rapamycin signaling pathway to be potential target for future research and pharmacological interventions.

TMPRSS3 mutations in autosomal recessive nonsyndromic hearing loss.

Nonsyndromic genetic deafness is highly heterogeneous in its clinical presentation, pattern of inheritance and underlying genetic causes. Mutations in TMPRSS3 gene encoding transmembrane serine protease account for <1 % of autosomal recessive nonsyndromic hearing loss (ARNSHL) in Caucasians. Targeted next generation sequencing in the index family with profound deaf parents and a son, and Sanger sequencing of selected TMPRSS3 gene regions in a cohort of thirty-five patients with suspected ARNSHL was adopted. A son and his mother in the index family were homozygous for TMPRSS3 c.208delC (p.His70Thrfs*19) variant. Father was digenic compound heterozygote for the same variant and common GJB2 c.35delG variant. Three additional patients from the ARNSHL cohort were homozygous for TMPRSS3 c.208delC. TMPRSS3 defects seem to be an important cause of ARNSHL in Slovenia resulting in uniform phenotype with profound congenital hearing loss, and satisfactory hearing and speech recognition outcome after cochlear implantation. Consequently, TMPRSS3 gene analysis should be included in the first tier of genetic investigations of ARNSHL along with GJB2 and GJB6 genes.

Weak association of glyoxalase 1 (GLO1) variants with autism spectrum disorder.

The prevalence of the autism spectrum disorder (ASD) was recently estimated to 1 in 88 children by the CDC MMWR. In up to 25 % of the cases, the genetic cause can be identified. Past studies identified increased level of advanced glycation end products (AGE) in the brain samples of ASD patients. The methylglyoxal (MG) is one of the main precursors for AGE formation. Humans developed effective mechanism of the MG metabolism involving two enzymes glyoxalase 1 (GLO1) and hydroxyacylglutathione hydrolase (HAGH). Our aim was to analyse genetic variants of GLO1 and HAGH in population of 143 paediatric participants with ASD. We detected 7 genetic variants in GLO1 and 16 variants in HAGH using high-resolution melting (HRM) analysis. A novel association between variant rs1049346 and ASD [OR (allele C)] = 1.5; 95 % CI = 1.1-2.2 and p < 0.05) was identified, and weak association between ASD and variant rs2736654 [OR (allele A)] = 2.2; 95 % CI = 0.99-4.9; p = 0.045) was confirmed. Additionally, a novel genetic variant (GLO1 c.484G > A, p.Ala161Thr) with predicted potentially damaging effect on the activity of the glyoxalase 1 that may contribute to the aetiology of ASD was identified in one participant with ASD. No association between genetic variants of the HAGH gene and ASD was found. Increased level of MG and, consequently, AGEs can induce oxidative stress, mitochondrial dysfunction and inflammation all of which have been implicated to act in the aetiology of the ASD. Our results indicate potential importance of MG metabolism in ASD. However, these results must be interpreted with caution until a causative relation is demonstrated.

Exploring early DNA methylation alterations in type 1 diabetes: implications of glycemic control.

Background: Prolonged hyperglycemia causes diabetes-related micro- and macrovascular complications, which combined represent a significant burden for individuals living with diabetes. The growing scope of evidence indicates that hyperglycemia affects the development of vascular complications through DNA methylation. Methods: A genome-wide differential DNA methylation analysis was performed on pooled peripheral blood DNA samples from individuals with type 1 diabetes (T1D) with direct DNA sequencing. Strict selection criteria were used to ensure two age- and sex-matched groups with no clinical signs of chronic complications according to persistent mean glycated hemoglobin (HbA1c) values over 5 years: HbA1c<7% (N=10) and HbA1c>8% (N=10). Results: Between the two groups, 8385 differentially methylated CpG sites, annotated to 1802 genes, were identified. Genes annotated to hypomethylated CpG sites were enriched in 48 signaling pathways. Further analysis of key CpG sites revealed four specific regions, two of which were hypermethylated and two hypomethylated, associated with long non-coding RNA and processed pseudogenes. Conclusions: Prolonged hyperglycemia in individuals with T1D, who have no clinical manifestation of diabetes-related complications, is associated with multiple differentially methylated CpG sites in crucial genes and pathways known to be linked to chronic complications in T1D.

PAX5 Alterations in a Consecutive Childhood B-Cell Acute Lymphoblastic Leukemia Cohort Treated Using the ALL IC-BFM 2009 Protocol.

In this study, we aimed to identify patients within our B-ALL cohort with altered PAX5. Our objective was to use a comprehensive analysis approach to characterize the types of genetic changes, determine their origin (somatic/germline), and analyze the clinical outcomes associated with them. A consecutive cohort of 99 patients with B-ALL treated at the Children's Hospital of the UMC Ljubljana according to the ALL IC-BFM 2009 protocol was included in our study. We used RNA sequencing data for gene expression analysis, fusion gene detection and single nucleotide variant identification, multiplex-ligation dependent probe amplification for copy number variation assessment, and Sanger sequencing for germline variant detection. PAX5 was impacted in 33.3% of our patients, with the genetic alterations ranging from CNVs and rearrangements to SNVs. The most common were CNVs, which were found in more than a third of patients, followed by point mutations in 5.2%, and gene rearrangements in 4.1%. We identified eight patients with a PAX5-associated genetic subtype that were previously classified as "B-other", and they showed intermediate outcomes. We showed higher minimal residual disease values at the end of induction and poorer event-free survival in hyperdiploid cases carrying duplications in PAX5 compared to other hyperdiploid cases. We also report an interesting case of a patient with PAX5::FKBP15 and a pathogenic variant in PTPN11 who underwent an early relapse with a monocytic switch. In conclusion, this study provides valuable insights into the presence, frequency, and prognostic significance of diverse PAX5 alterations in B-ALL patients, highlighting the complexity of genetic factors and their impact on patient outcomes.

Genetic and clinical characteristics of patients with lipoprotein lipase deficiency from Slovenia and Pakistan: case series and systematic literature review.

Introduction: Hypertriglyceridemia (HTG) is a complex disorder caused by genetic and environmental factors that frequently results from loss-of-function variants in the gene encoding lipoprotein lipase (LPL). Heterozygous patients have a range of symptoms, while homozygous LPL deficiency presents with severe symptoms including acute pancreatitis, xanthomas, and lipemia retinalis. Methods: We described the clinical characteristics of three Slovenian patients (an 8-year-old female, an 18-year-old man, and a 57-year-old female) and one Pakistani patient (a 59-year-old male) with LPL deficiency. We performed next-generation sequencing (NGS) targeting all coding exons and intron-exon boundaries of the LPL gene, and Sanger sequencing for variant confirmation. In addition, we performed a systematic literature review of all cases with three identified variants and described their clinical characteristics. Results: Two Slovenian patients with a heterozygous pathogenic variant NM_000237.3:c.984G>T (p.Met328Ile) were diagnosed within the first three years of life and had triglyceride (TG) values of 16 and 20 mmol/L. An asymptomatic Pakistani patient with TG values of 36.8 mmol/L until the age of 44 years, was identified as heterozygous for a pathogenic variant NM_000237.3:c.724G>A (p.Asp242Asn). His TG levels dropped to 12.7 mmol/L on dietary modifications and by using fibrates. A Slovenian patient who first suffered from pancreatitis at the age of 18 years with a TG value of 34 mmol/L was found to be homozygous for NM_000237.3:c.337T>C (p.Trp113Arg). Conclusions: Patients with LPL deficiency had high TG levels at diagnosis. Homozygous patients had worse outcomes. Good diet and medication compliance can reduce severity.

Severe progressive obstructive cardiomyopathy and renal tubular dysfunction in Donohue syndrome with decreased insulin receptor autophosphorylation due to a novel INSR mutation.

UNLABELLED: Donohue syndrome (leprechaunism; OMIM *246200) is a rare, recessively inherited disorder of extreme insulin resistance due to mutations in the insulin receptor gene (INSR) causing either defects in insulin binding or receptor autophosphorylation and tyrosine kinase activity. We report a patient with pronounced clinical picture of leprechaunism who developed severe progressive hypertrophic obstructive cardiomyopathy (HOCM) and renal tubular dysfunction which improved on continuous subcutaneous infusion of recombinant human insulin-like growth factor-1 (rhIGF-I). INSR gene molecular analysis and insulin receptor (IR) autophosphorylation on cultured fibroblasts were performed. A novel homozygous missense mutation p.Leu795Pro was found, located in the extracellular portion of the ß subunit of the insulin receptor. The post-binding defect of the insulin receptor signaling in cultured fibroblasts demonstrated decreased insulin receptor autophosphorylation. CONCLUSION: Treatment with rhIGF-I partially reversed severe progressive HOCM and renal tubular dysfunction in a patient with Donohue syndrome associated with a novel p.Leu795Pro INSR gene mutation causing a severe decrease in IR autophosphorylation.

Non-alcoholic fatty liver disease in a pediatric patient with heterozygous familial hypobetalipoproteinemia due to a novel APOB variant: a case report and systematic literature review.

Background: Familial hypobetalipoproteinemia (FHBL) is an autosomal semi-dominant disorder usually caused by variants in the APOB gene that frequently interferes with protein length. Clinical manifestations include malabsorption, non-alcoholic fatty liver disease, low levels of lipid-soluble vitamins, and neurological, endocrine, and hematological dysfunction. Methods: Genomic DNA was isolated from the blood samples of the pediatric patient with hypocholesterolemia and his parents and brother. Next-generation sequencing (NGS) was performed, and an expanded dyslipidemia panel was employed for genetic analysis. In addition, a systematic review of the literature on FHBL heterozygous patients was performed. Case report: Genetic investigation revealed the presence of a heterozygous variant in the APOB (NM_000384.3) gene c.6624dup[=], which changes the open reading frame and leads to early termination of translation into the p.Leu2209IlefsTer5 protein (NP_000375.3). The identified variant was not previously reported. Familial segregation analysis confirmed the variant in the mother of the subject, who also has a low level of low-density lipoprotein and non-alcoholic fatty liver disease. We have introduced therapy that includes limiting fats in the diet and adding lipid-soluble vitamins E, A, K, and D and calcium carbonate. We reported 35 individuals with APOB gene variations linked to FHBL in the systematic review. Conclusion: We have identified a novel pathogenic variant in the APOB gene causing FHBL in pediatric patients with hypocholesterolemia and fatty liver disease. This case illustrates the importance of genetic testing for dyslipidemias in patients with significant decreases in plasma cholesterol as we can avoid damaging neurological and ophthalmological effects by sufficient vitamin supplementation and regular follow-ups.

Clinical and genetic characteristics of a patient with phosphoribosyl pyrophosphate synthetase 1 deficiency and a systematic literature review.

Phosphoribosylpyrophosphate synthetase 1 (PRS-I) is an enzyme involved in nucleotide metabolism. Pathogenic variants in the PRPS1 are rare and PRS-I deficiency can manifest as three clinical syndromes: X-linked non-syndromic sensorineural deafness (DFN2), X-linked Charcot-Marie-Tooth neuropathy type 5 (CMTX5) and Arts syndrome. We present a Slovenian patient with PRS-I enzyme deficiency due to a novel pathogenic variant - c.424G > A (p.Val142Ile) in the PRPS1 gene, who presented with gross motor impairment, severe sensorineural deafness, balance issues, ataxia, and frequent respiratory infections. In addition, we report the findings of a systemic literature review of all described male cases of Arts syndrome and CMTX5 as well as intermediate phenotypes. As already proposed by other authors, our results confirm PRS-I deficiency should be viewed as a phenotypic continuum rather than three separate syndromes because there are multiple reports of patients with an intermediary clinical presentation.

Integrative Transcriptomic Profiling of the Wilms Tumor.

Our study aimed to identify relevant transcriptomic biomarkers for the Wilms tumor, the most common pediatric kidney cancer, independent of the histological type and stage. Using next-generation sequencing, we analyzed the miRNA profiles of 74 kidney samples, which were divided into two independent groups: fresh frozen tissue and formalin-fixed paraffin-embedded tissue samples. Subsequent mRNA expression profiling and pathway analysis were performed to establish the interplay and potential involvement of miRNAs and mRNA in the Wilms tumor. Comparative analysis, irrespective of post-dissection tissue processing, revealed 41 differentially expressed miRNAs, with 27 miRNAs having decreased expression and 14 miRNAs having increased expression in the Wilms tumor tissue compared to healthy kidney tissue. Among global mRNA transcriptomic profile differences, cross-sectional analysis suggested a limited list of genes potentially regulated by differentially expressed miRNAs in the Wilms tumor. This study identified the comprehensive miRNA and mRNA profile of the Wilms tumor using next-generation sequencing and bioinformatics approach, providing better insights into the pathogenesis of the Wilms tumor. The identified Wilms tumor miRNAs have potential as biomarkers for the diagnosis and treatment of the Wilms tumor, regardless of histological subtype and disease stage.

Five novel mutations and two large deletions in a population analysis of the phenylalanine hydroxylase gene.

Mutational spectrum of the phenylalanine hydroxylase (PAH) deficiency was investigated in 107 families (90% of the Slovene PKU population). The entire coding region of the PAH gene was analyzed with dHPLC to select the samples where subsequently the automated sequencing analysis was performed. MLPA analysis was performed to identify large deletions, which were later confirmed with long-range PCR. Correlations with patients' phenotypes and genotype-based predictions of BH(4)-responsiveness were assessed. Altogether, disease-causing mutations were identified on 209 alleles (detection rate 97.7%). A spectrum of 36 different disease-causing mutations was identified: 20 missense mutations (80% of the alleles), eight splicing mutations (13% of the alleles), one nonsense mutation (0.5% of the alleles), four small deletions with frame shift (6% of the alleles), one small insertion with frame shift (0.5% of the alleles), and two large deletions (2% of the alleles). The most frequent mutation was p.R408W in exon 12, representing 29% of the alleles, which is in concordance with other neighboring and/or Slavic PKU populations. Other common mutations were: p.R158Q, p.A403V, p.P281L and p.E390G, accounting for 9%, 7%, 7% and 7% of the alleles respectively. Five novel mutations were detected: c.43_44insAG, c.56_59+1delACAGG, p.V45A, p.L62P and p.R157S. Large deletion of exon 5 (EX5del955) was found in three patients and a deletion of exon 3 (EX3del4765) in one patient. A spectrum of 64 different genotypes was found, seven of them accounting for over than a third of all families. Among thirteen families with homozygous mutation (13% of the PKU population), 10 had p.R408W, two had p.R158Q and one had p.E390G. Among 107 families, 58 were classified as classic PKU (54.2%), 28 as mild PKU (25.9%) and 21 as MHP (19.6%). Twenty-six different genotypes (40.6%) were predicted to be BH(4)-responsive, represented by 38 different families (35.5%).

An Intron c.103-3T>C Variant of the AMELX Gene Causes Combined Hypomineralized and Hypoplastic Type of Amelogenesis Imperfecta: Case Series and Review of the Literature

Amelogenesis imperfecta (AI) is a heterogeneous group of genetic disorders of dental enamel. X-linked AI results from disease-causing variants in the AMELX gene. In this paper, we characterise the genetic aetiology and enamel histology of female AI patients from two unrelated families with similar clinical and radiographic findings. All three probands were carefully selected from 40 patients with AI. In probands from both families, scanning electron microscopy confirmed hypoplastic and hypomineralised enamel. A neonatal line separated prenatally and postnatally formed enamel of distinctly different mineralisation qualities. In both families, whole exome analysis revealed the intron variant NM_182680.1: c.103-3T>C, located three nucleotides before exon 4 of the AMELX gene. In family I, an additional variant, c.2363G>A, was found in exon 5 of the FAM83H gene. This report illustrates a variant in the AMELX gene that was not previously reported to be causative for AI as well as an additional variant in the FAM83H gene with probably limited clinical significance.

A Novel Splice-Site Deletion in the POU1F1 Gene Causes Combined Pituitary Hormone Deficiency in Multiple Sudanese Pedigrees.

Pathogenic variants within the gene encoding the pituitary-specific transcription factor, POU class 1 homeobox 1 (POU1F1), are associated with combined pituitary hormone deficiency (CPHD), including growth hormone, prolactin, and thyrotropin stimulating hormone deficiencies. The aim of the study was to identify genetic aetiology in 10 subjects with CPHD from four consanguineous Sudanese families. Medical history, as well as hormonal and radiological information, was obtained from participants' medical records. Targeted genetic analysis of the POU1F1 gene was performed in two pedigrees with a typical combination of pituitary deficiencies, using Sanger sequencing, and whole-exome sequencing was performed in the other two pedigrees, where hypocortisolism and additional neurologic phenotypes were also initially diagnosed. In POU1F1 gene (NM_001122757.2) a novel homozygous splice-site deletion-namely, c.744-5_749del-was identified in all 10 tested affected family members as a cause of CPHD. Apart from typical pituitary hormonal deficiencies, most patients had delayed but spontaneous puberty; however, one female had precocious puberty. Severe post-meningitis neurologic impairment was observed in three patients, of whom two siblings had Dyke-Davidoff-Masson syndrome, and an additional distantly related patient suffered from cerebral infarction. Our report adds to the previously reported POU1F1 gene variants causing CPHD and emphasises the importance of genetic testing in countries with high rates of consanguineous marriage such as Sudan. Genetic diagnostics elucidated that the aetiologies of hypopituitarism and brain abnormalities, identified in a subset of affected members, were separate. Additionally, as central hypocortisolism is not characteristic of POU1F1 deficiency, hydrocortisone replacement therapy could be discontinued. Elucidation of a genetic cause, therefore, contributed to the more rational clinical management of hypopituitarism in affected family members.

Pathogenesis of Type 1 Diabetes: Established Facts and New Insights.

Type 1 diabetes (T1D) is an autoimmune disease characterized by the T-cell-mediated destruction of insulin-producing ß-cells in pancreatic islets. It generally occurs in genetically susceptible individuals, and genetics plays a major role in the development of islet autoimmunity. Furthermore, these processes are heterogeneous among individuals; hence, different endotypes have been proposed. In this review, we highlight the interplay between genetic predisposition and other non-genetic factors, such as viral infections, diet, and gut biome, which all potentially contribute to the aetiology of T1D. We also discuss a possible active role for ß-cells in initiating the pathological processes. Another component in T1D predisposition is epigenetic influences, which represent a link between genetic susceptibility and environmental factors and may account for some of the disease heterogeneity. Accordingly, a shift towards personalized therapies may improve the treatment results and, therefore, result in better outcomes for individuals in the long-run. There is also a clear need for a better understanding of the preclinical phases of T1D and finding new predictive biomarkers for earlier diagnosis and therapy, with the final goal of reverting or even preventing the development of the disease.

The Role of Epigenetic Modifications in Late Complications in Type 1 Diabetes.

Type 1 diabetes is a chronic autoimmune disease in which the destruction of pancreatic ß cells leads to hyperglycemia. The prevention of hyperglycemia is very important to avoid or at least postpone the development of micro- and macrovascular complications, also known as late complications. These include diabetic retinopathy, chronic renal failure, diabetic neuropathy, and cardiovascular diseases. The impact of long-term hyperglycemia has been shown to persist long after the normalization of blood glucose levels, a phenomenon known as metabolic memory. It is believed that epigenetic mechanisms such as DNA methylation, histone modifications, and microRNAs, play an important role in metabolic memory. The aim of this review is to address the impact of long-term hyperglycemia on epigenetic marks in late complications of type 1 diabetes.

Heterozygous NPR2 Variants in Idiopathic Short Stature.

Heterozygous variants in the NPR2 gene, which encodes the B-type natriuretic peptide receptor (NPR-B), a regulator of skeletal growth, were reported in 2-6% cases of idiopathic short stature (ISS). Using next-generation sequencing (NGS), we aimed to assess the frequency of NPR2 variants in our study cohort consisting of 150 children and adolescents with ISS, describe the NPR2 phenotypic spectrum with a growth pattern including birth data, and study the response to growth hormone (GH) treatment. A total of ten heterozygous pathogenic/likely pathogenic NPR2 variants and two heterozygous NPR2 variants of uncertain significance were detected in twelve participants (frequency of causal variants: 10/150, 6.7%). During follow-up, the NPR2 individuals presented with a growth pattern varying from low-normal to significant short stature. A clinically relevant increase in BMI (a mean gain in the BMI SDS of +1.41), a characteristic previously not reported in NPR2 individuals, was observed. In total, 8.8% participants born small for their gestational age (SGA) carried the NPR2 causal variant. The response to GH treatment was variable (SDS height gain ranging from -0.01 to +0.74). According to the results, NPR2 variants present a frequent cause of ISS and familial short stature. Phenotyping variability in growth patterns and variable responses to GH treatment should be considered.