The significant variability in the clinical manifestations of COL2A1-associated skeletal dysplasias makes it necessary to conduct a clinical and genetic analysis of individual nosological variants, which will contribute to improving our understanding of the pathogenetic mechanisms and prognosis. We presented the clinical and genetic characteristics of 60 Russian pediatric patients with type II collagenopathies caused by previously described and newly identified variants in the COL2A1 gene. Diagnosis confirmation was carried out by new generation sequencing of the target panel with subsequent validation of the identified variants using automated Sanger sequencing. It has been shown that clinical forms of spondyloepiphyseal dysplasias predominate in childhood, both with more severe clinical manifestations (58%) and with unusual phenotypes of mild forms with normal growth (25%). However, Stickler syndrome, type I was less common (17%). In the COL2A1 gene, 28 novel variants were identified, and a total of 63% of the variants were found in the triple helix region resulted in glycine substitution in Gly-XY repeats, which were identified in patients with clinical manifestations of congenital spondyloepiphyseal dysplasia with varying severity, and were not found in Stickler syndrome, type I and Kniest dysplasia. In the C-propeptide region, five novel variants leading to the development of unusual phenotypes of spondyloepiphyseal dysplasia have been identified.

Background: The aim of this study was to evaluate the association of the carriage of the rs2244613 polymorphism of the CES1 gene with clopidogrel resistance as well as to evaluate the effectiveness of antiplatelet therapy in the carriers of this marker who have had acute coronary syndrome (ACS). This study also analyzes the procedure of percutaneous coronary intervention and compares the rs2244613 carrier rate between patients with ACS and healthy participants. Methods: The study involved 81 patients diagnosed with ACS and 136 conditionally healthy participants. The optical detection of platelet agglutination by VerifyNow was employed to measure residual platelet reactivity in patients with ACS. The rs2244613 polymorphism was determined using real-time polymerase chain reaction. Results: According to the results, the AA genotype of the rs2244613 polymorphism of the CES1 gene was detected in 37 patients (45.6%), the CA genotype in 42 patients (51.8%) and the CC genotype in 2 patients (2.6%). The level of residual platelet reactivity in rs2244613 carriers was higher compared with patients who did not have this allelic variant: 183.23 PRU ± 37.24 vs. 154.3 PRU ± 60.36 (p = 0.01). The frequencies of the minor allele C were 28.4% and 28.3% in patients with ACS and healthy participants, respectively. The results of the linear statistical model PRU due to CES1 genotype were as follows: df = 1, F = 6.96, p = 0.01). The standardized beta was 0.285 (p = 0.01) and R² was 0.081. However, we also added CYP2C19*2 and *17 into the linear regression model. The results of the model were as follows: df = 3, F = 5.1, p = 0.003) and R² was 0.166. Conclusions: We identified a statistically significant correlation between the carriage of the rs2244613 polymorphism of the CES1 gene and the level of residual platelet aggregation among patients with ACS and the procedure of percutaneous coronary intervention.

Background: Pycnodysostosis (PD, OMIM # 265800) is a rare variant of skeletal dysplasia with an autosomal recessive type of inheritance, characterized by a combination of specific features such as disproportionate nanism, generalized osteosclerosis, and distinct craniofacial dysmorphism. Radiographic features include acro‐osteolysis of the distal phalanges in association with sclerosing bone lesions with multiple fractures. The polymorphism of the clinical manifestations of pycnodysostosis and low prevalence of the disorder lead to the difficulties with early.Methods: The following tests were used for diagnostics: genealogical analysis, clinical examination, neurological examination according to the standard method with an assessment of the psychoemotional sphere, radiological analysis, searching for pathogenic variants in the CTSK gene by the automated Sanger sequencing.Results: We describe first clinical and genetic characteristics of three Russian patients with pycnodysostosis from unrelated families. Two patients have a novel homozygous nucleotide substitution c.746T>A (p. Ile249Asn), and one has a previously described homozygous pathogenic variant c.746T>C (p.Ile249Thr) in the CTSK gene. In all three cases, a transition or transversion was found at nucleotide position 746 in exon 6 of the CTSK gene, leading to two different amino acid substitutions in the polypeptide chain. The obtained results may indicate the presence of a major pathogenic variant in the CTSK gene, leading to the typical manifestation of the disease.Conclusion: The data presented in the study enlarge the clinical, radiological, and mutational spectrum of pycnodysostosis. Typical clinical manifestations and the small size of the CTSK gene make the automated Sanger sequencing the optimal method for diagnosis of pycnodysostosis.

Introduction. Juvenile idiopathic arthritis (JIA) is a common multifactorial disease characterized by the presence of chronic inflammation in the joints, entheses and other structures of the musculoskeletal system in combination with a certain range of extraskeletal disorders. Vast variety of JIA clinical variants and the variability of the disease course make primary and differential diagnosis difficult, which often leads to a delayed start of treatment and an inadequate choice of medical therapy or, conversely, an excess of medication. In the range of differential diagnostic conditions that have similar symptoms and are manifested by severe arthralgia, gait disturbance, joint stiffness, as well as the presence of effusion and gradual progression of bone destruction mainly in the epiphyseal plate, one should remember about hereditary skeletal dysplasias, primarily from a genetically heterogeneous group of multiple epiphyseal dysplasias (MED). The aim of the study – description of the clinical and genetic characteristics of three patients with various genetic variants of MED and defining approaches for their differential diagnosis with JIA. Materials and methods. There were three patients from three unrelated families aged from 7 to 13 years old under our supervision. To clarify the diagnosis, a genealogical analysis, a clinical examination of patients and first-degree relatives, as well as an assessment of X-ray images of long tubular bones were carried out. Molecular genetic confirmation of the MED diagnosis types 1 and 2 was based on the results of custom panel sequencing consisting of 166 genes responsible for the development of hereditary skeletal pathology. To clarify the molecular genetic diagnosis of MED type 4, an analysis of the SLC26A2 gene was performed using automated Sanger sequencing. Results. Anamnestic, clinical, radiological, and molecular genetic characteristics of three unrelated patients with different genetic types of MED caused by variants in the COMP, SLC26A2, and COL9A2 genes were analyzed. The first symptoms of the disease in observed patients with three different genetic variants of MED occurred at the age of 2–3 years old and were characterized by gait disturbance and climbing stairs difficulties. Gradually, these symptoms were accompanied by pain in large joints. According to the ultrasound examination of the joints, signs of synovitis were noted, as a result they were diagnosed with JIA (polyarticular variant, seronegative for rheumatoid and antinuclear factor) and immunosuppressive therapy were prescribed without significant effect. The atypical course of the JIA was the reason for additional examination of patients by an orthopedist and geneticist. Careful analysis of the large joints radiographs made it possible to suspect one of the variants of MED in our patients based on the detection of distinctive signs, which were characterized by abnormal ossification (diminished size and flattening) of the epiphyses and abnormal shape and structure of the femoral head epiphysis. Molecular genetic analysis was performed to confirm the diagnosis. As a result, a pathogenic variant of the nucleotide sequence in the COMP gene was detected in one of the patients, two pathogenic variants in the SLC26A2 gene in another patient, and one pathogenic variant in the COL9A2 gene in the third patient, which made it possible to confirm the final diagnosis of MED type 1 with an autosomal dominant type of inheritance, MED type 4 with an autosomal recessive type of inheritance and MED type 2 with an autosomal dominant type of inheritance, respectively. Based on the results of our own research and analysis of the literature data, key directions for the differential diagnosis of MED and JIA were formulated. It is shown that the analysis of the X-ray images of patients is essential in differential diagnosis. Conclusion. Despite the significant overlap of the clinical symptoms between JIA and MED, the key to the early diagnosis of MED is a comprehensive examination, which included genealogical analysis, features of clinical manifestations and disease course in combination with distinctive radiological signs including delayed ossification of the epiphyses of tubular bones typical for MED. However, the question remains about the probability of a combined nature of osteoarticular disorders, i. e., the possible development of JIA in patients with hereditary skeletal dysplasias which requires in-depth study in the future.

Background. Multiple epiphysal dysplasia (MED) type 1 (OMIM: 132400) is one of 7 genetic variants of this group of skeletal dysplasias described to date. The disease is caused by mutations in the COMP gene located on chromosome 19p13.1. The presence of muscle hypotonia and ligamentous laxity, as well as a moderate increase in the level of creatinephosphokinase activity, can lead to misdiagnosis of myopathy. Objective: to analyze the clinical and genetic characteristics of type 1 MED caused by mutations in the COMP gene in a series of Russian patients. Differential diagnosis was focused on the distinctive features of the disorder and hereditary myopathies. Materials and methods. We observed 8 patients from 7 families aged 7 to 15 years with MED type 1 caused by heterozygous mutations in the COMP gene. To confirm the diagnosis, the following methods were used: genealogical analysis, clinical examination, neurological examination with psycho-emotional testing, radiography and targeted sequencing of a panel consisting of 166 genes responsible for the development of inherited skeletal pathology. Results. Case history, clinical, radiological and genetic characteristics of 8 patients with MED type 1 caused by mutations in the COMP gene were analyzed. The first clinical manifestations of the disease were recorded from the age of 2–3 years and were characterized by gait disturbances, muscle weakness, difficulties with climbing stairs, frequent falls when walking, the inability to get up from the floor and from a squatting position and hypermobility of the joints. Electroneuromyographic study did not reveal the signs of miopathy. In two patients, a moderate increase in the creatinekinase level of up to 250–360 u / l was found. All patients were surveyed by neurologists for several years with a clinical diagnosis of congenital myopathy. At the age of 5–6 years patients COMPlained knee and ankle pain, which was assumed as rheumatic arthropathy. X-ray examination revealed typical signs of deficient ossification of the epiphyses. The next-generation sequencing analysis revealed seven single nucleotide variants in the COMP gene that lead to MED type 1. Three of the found variants here identified for the first time. As previously described, the majority of nucleotide variants (six out of seven) were localized in the 8–14 exons of the COMP gene and led to amino acid substitutions in calmodulin-like protein domain repeats, and only one substitution was localized in the C-terminal region of the protein molecule. Conclusion. In most patients with MED caused by mutations in the COMP gene, the first symptoms of the disease are gait disturbance, muscle weakness, and Gowers» maneuvers. The presence of these symptoms, along with a moderate increase in the level of creatinephosphokinase activity, often precedes the onset of clinical manifestations of skeletal dysplasia, leading to a misdiagnosis with myopathies. Accession of expressive arthralgias to these symptoms was mistakenly identified as reactive arthritis. X-ray examination of patients’ long bones helps to suspect the presence of MED. This X-ray imaging shows specific signs of epiphyses damage. A molecular-genetic analysis needs to be done to diagnose the genetic variant, caused by mutations in gene COMP.

Steel syndrome (STLS, OMIM# 615155) is a rare skeletal dysplasia associated with biallelic pathogenic variants in COL27A1 gene. To date, more than 60 patients with STLS have been reported in the literature, the majority of whom are Puerto Rican. STLS in all individuals from this population is associated with the homozygous p.Gly697Arg missense variant, confirming the founder effect. Meanwhile, just 17 cases from 14 unrelated non-Puerto Rican families have been reported, including two fetuses. Here we present two pediatric cases of STLS from Russian and Uzbek populations, associated with two novel compound heterozygous splice variants c.2673 + 4A > G, c.2619 + 1G > A and a novel homozygous missense variant c.3988G > C p. (Gly1330Arg). Splicing assay was performed to investigate the novel donor splice site variants' effects on mRNA structure and expression. Both cases demonstrated skeletal features characteristic of STLS, including acetabular dysplasia or hip dislocation, carpal coalition, radial head dislocation, with additional extraskeletal manifestations observed in one patient. A review of 63 STLS cases revealed key diagnostic criteria present in the majority of individuals, though phenotypic variability was observed depending on variant type and population origin. It is proposed that biallelic Gly substitutions within the triple-helical domain associated with the ‘classic' skeletal phenotype of STLS initially characterized in Steel's study. In contrast, patients with homozygous or compound heterozygous frameshift or nonsense variants more frequently demonstrate a higher prevalence of extraskeletal manifestations and severe short stature. Our study expands the genetic and clinical spectrum of STLS in non-Puerto Rican populations and explores potential genotype-phenotype correlations, which will contribute to early disease diagnosis and the selection of optimal patient management strategies, avoiding unnecessary interventions.