Association of serum levels of aggrecan ARGS,NITEGE fragments and radiologic knee osteoarthritis in Tunisian patients

ObjectivesProteolytic degradation of aggrecan is a hallmark of the pathology of osteoarthritis. The aim of this study was to develop enzyme-linked immunosorbent assay (ELISA) to quantify the serum levels of specific aggrecan fragments generated by aggrecanases-mediated cleavage. We investigated the relationships between these two aggrecan degradations fragments and urinary CTX-II levels.MethodsThe competitive ELISAs employ a polyclonal antibody raised against the aggrecan fragments containing two neoepitopes NITEGE³⁷³ and ³⁷⁴ARGSVI. We measured serum levels of ARGSV and NITEGE in 125 women with knee osteoarthritis (mean ± SD age of 53.6 ± 7.6 years, mean ± SD disease duration of 3.6 ± 3.8 years), and 57 women age-matched controls.ResultsAggrecan neoepitopes assays showed an intra- and inter-assay imprecision (CV) lower than 20% for both tests and good linearity. Median serum ARGSVI (by 18%; P = 0.002), and NITEGE (36.4%; P < 0.001) levels were significantly decreased in patients with knee osteoarthritis compared with controls. Minimal joint space width was negatively correlated with ARGSVI (r = –0.368, P = 0.04) and NITEGE (r = –0.274, P = 0.038) in knee osteoarthritis patients. Median urinary CTX-II levels were significantly increased by 39.5% (P = 0.001) in knee OA patients compared with controls.ConclusionMarkers of degradation aggrecan were analyzed for the first time in an African osteoarthritis population. These markers can be used to monitor aggrecanase activity in human joint disease. Their combination with CTX-II can improve clinical investigation of patients with osteoarthritis patients.     

Skeletal clinical characteristics of osteogenesis imperfecta caused by haploinsufficiency mutations in COL1A1

COL1A1 haploinsufficiency mutations lead to the mildest form of osteogenesis imperfecta (OI), OI type I. The skeletal clinical characteristics resulting from such mutations have not been characterized in detail. In this study we assessed 86 patients (36 male, 50 female; mean age 13.3 years; range, 0.6 to 54 years) with COL1A1 haploinsufficiency mutations, of whom 70 were aged 21 years or less (“pediatric” patients). Birth history was positive for fracture or long‐bone deformity in 12% of patients. The average rate of long‐bone fracture (femur, tibia/fibula, humerus, radius/ulna) in pediatric patients was 0.62 fractures per year, one‐half of which affected the tibia/fibula. Long‐bone fracture rate was negatively associated with age and lumbar spine areal bone mineral density. Vertebral compression fractures were observed in 71% of the 58 pediatric patients who had lateral spine radiographs. The median number of vertebral fractures was higher for females (median 4; range, 0 to 14) than for males (median 1; range, 0 to 8) (p = 0.03). Lumbar spine areal bone mineral density was negatively associated with the severity of vertebral compression fractures, as reflected in the spine deformity index. Scoliosis was present in about 30% of pediatric patients but the Cobb angle was <30 degrees in all cases. The average final height Z‐score was –1.1, representing a deficit of 8 to 10 cm compared to the general population. In summary, OI patients with COL1A1 haploinsufficiency mutations have high rates of significant skeletal involvement. Systematic follow‐up of growing patients with COL1A1 haploinsufficiency mutations including radiographic screening for vertebral compression fractures and scoliosis is warranted.     

CDK13-related disorder: Report of a series of 18 previously unpublished individuals and description of an epigenetic signature

PurposeRare genetic variants in CDK13 are responsible for CDK13-related disorder (CDK13-RD), with main clinical features being developmental delay or intellectual disability, facial features, behavioral problems, congenital heart defect, and seizures. In this paper, we report 18 novel individuals with CDK13-RD and provide characterization of genome-wide DNA methylation.MethodsWe obtained clinical phenotype and neuropsychological data for 18 and 10 individuals, respectively, and compared this series with the literature. We also compared peripheral blood DNA methylation profiles in individuals with CDK13-RD, controls, and other neurodevelopmental disorders episignatures. Finally, we developed a support vector machine–based classifier distinguishing CDK13-RD and non–CDK13-RD samples.ResultsWe reported health and developmental parameters, clinical data, and neuropsychological profile of individuals with CDK13-RD. Genome-wide differential methylation analysis revealed a global hypomethylated profile in individuals with CDK13-RD in a highly sensitive and specific model that could aid in reclassifying variants of uncertain significance.ConclusionWe describe the novel features such as anxiety disorder, cryptorchidism, and disrupted sleep in CDK13-RD. We define a CDK13-RD DNA methylation episignature as a diagnostic tool and a defining functional feature of the evolving clinical presentation of this disorder. We also show overlap of the CDK13 DNA methylation profile in an individual with a functionally and clinically related CCNK-related disorder.     

Molecular Epidemiology of SARS-CoV-2 in Tunisia (North Africa) through Several Successive Waves of COVID-19

Documenting the circulation dynamics of SARS-CoV-2 variants in different regions of the world is crucial for monitoring virus transmission worldwide and contributing to global efforts towards combating the pandemic. Tunisia has experienced several waves of COVID-19 with a significant number of infections and deaths. The present study provides genetic information on the different lineages of SARS-CoV-2 that circulated in Tunisia over 17 months. Lineages were assigned for 1359 samples using whole-genome sequencing, partial S gene sequencing and variant-specific real-time RT-PCR tests. Forty-eight different lineages of SARS-CoV-2 were identified, including variants of concern (VOCs), variants of interest (VOIs) and variants under monitoring (VUMs), particularly Alpha, Beta, Delta, A.27, Zeta and Eta. The first wave, limited to imported and import-related cases, was characterized by a small number of positive samples and lineages. During the second wave, a large number of lineages were detected; the third wave was marked by the predominance of the Alpha VOC, and the fourth wave was characterized by the predominance of the Delta VOC. This study adds new genomic data to the global context of COVID-19, particularly from the North African region, and highlights the importance of the timely molecular characterization of circulating strains.     

SLC26A4 variations among Graves' hyper-functioning thyroid gland

Deleterious mutations of SLC26A4 cause Pendred syndrome (PS), an autosomal recessive disorder comprising goitre and deafness with enlarged vestibular aqueducts (EVA), and nonsyndromic hearing loss (NSHL). However, the SLC26A4 hyperactivity was recently associated with the emergence of autoimmune thyroid diseases (AITD) and asthma among human and mouse model. Here, by direct sequencing, we investigate the sequences of the 20 coding exons (2 to 21) of SLC26A4 and their flanking intron-exon junctions among patients affected with Graves' disease (GD) hyperthyroidism. Ten mono-allelic variants were identified, seven of which are intronic and previously unreported. Two, c.898A>C (p.I300L) and c.1061T>C (p.F354S), of the three exonic variants are non synonymous. The p.F354S variant is already described to be involved in PS or NSHL inheritances. The exploration by PCR-RFLP of p.I300L and p.F354S variants among 132 GD patients, 105 Hashimoto thyroiditis (HT), 206 Healthy subjects and 102 families with NSHL have shown the presence of both variants. The p.F354S variation was identified both among patients (1~HT and 3 GD) and healthy subjects (n=5). Whereas, the p.I300L variant was identified only in GD patients (n=3). Our studies provide evidence of the importance of systematic analysis of SLC26A4 gene sequences on models other than deafness. This approach allows the identification of new variants and the review of the pathogenic effects of certain mono-allelic variants reported responsible for PS and NSHL development.     

Analysis of immunoglobulin heavy chain genes rearrangement by PCR from paraffin-embedded tissue in B-cell lymphomes in Tunisia

OBJECTIVE: To study the lymphoid clonality on Tunisian B-cell lymphomas cases by polymerase chain reaction (PCR)-based techniques using DNA from paraffin-embedded tissues. MATERIAL AND METHODS: Here we conducted a retrospective PCR clonality study on 73 cases of B-cell lymphomas and 12 reactive lymphoid tissues. The quality of DNA extracted was tested by beta-globin PCR. Consensus primers directed at the FRIII-VH and FRII-VH regions of the immunoglobulin heavy chain (IgH) gene were used to detect clonality. RESULTS: The results showed that 52 of 73 (71%) B-cell lymphomas exhibited good quality of amplifiable DNA. Clonality was found in 77% of cases using the set of primers FRIIIa/LJH/VLJH and in 65.5% using the set of primers FRIIa/LJH/VLJH. Lymphomas derived from pregerminal centre showed a high rate detection of clonal IgH gene rearrangement (100%) compared to other group of tumors derived from germinal centre or postgerminal centre (74.5%). None of the polyclonal controls gave a clonal pattern. CONCLUSION: This is the first large series of PCR clonality study of IgH gene rearrangements on B-cell lymphoma from Tunisia. Our results were similar to other reports in terms of sensitivity and specificity of these techniques and confirm the interest of that PCR for detecting clonal IgH gene rearrangements in lymphoma.     

Analysis of MHC genes in a Tunisian isolate with autoimmune thyroid diseases: implication of TNF -308 gene polymorphism

Autoimmune thyroid diseases (AITDs), which include Hashimoto thyroiditis (HT), Graves' disease (GD) and primary idiopathic myxoedema (PIM), are recognized as multifactorial diseases. In this study, we have examined single and haplotypic genetic variation across the major histocompatibility complex (MHC) in a Tunisian isolate with a high prevalence of AITDs (62 patients: 32 with GD, 9 with HT and 21 with PIM). Genotyping was performed for HLA class I and II alleles as well as polymorphisms within tumor necrosis factor (TNF), lymphotoxin alpha (TLalpha) and heat shock protein (HSP70-02 and HSP70-hom) genes. Our results showed association of HLA-A2-B50-TNF 2 haplotype with AITDs (p = 0.045). Linkage analysis using Simwalk2 program has shown significant result with TNF -308 gene polymorphism (p = 0.03). The FBAT has given evidence for genetic association with TNF -308 and HLA-DR gene polymorphisms. TNF 2 allele was associated with GD (p = 0.0011), whereas TNF 1, HLA-DR11 and DR12 (p = 0.0039, p = 0.00089 and p = 0.0056, respectively) were rather implicated in HT pathogenesis. Results found by TDT-STDT have confirmed the involvement of the TNF -308 gene polymorphism in AITD pathogenesis (p < 10(-9)).