INTRODUCTION:The OPG/RANKL ratio is an important determinant of bone mass and skeletal integrity, and it is also crucial in the pathogenesis of bone diseases. So far, few studies have been conducted to determine the reference values of OPG and RANKL in developmental age. AIM OF THE STUDY:The aim of the study was to determine the reference values of OPG, sRANKL concentrations and the OPG/RANKL ratio in healthy children, as well as to assess the impact of selected demographic factors and biological development on their concentrations. MATERIAL AND METHODS:Data obtained from medical records of 56 healthy patients aged 1-18 years were analyzed. Anthropometric measurements were analyzed for each child and the stage of puberty was assessed using the standard Tanner scale criteria. OPG and sRANKL levels were determined by ELISA with kits from Biomedica. The osteoprotegerin bioactivity index (OPG/RANKL ratio) was calculated for each patient by dividing OPG values by sRANKL (OPG/RANKL ratio). RESULTS:In the studied population of healthy children and adolescents, the OPG serum concentration reference value was established at 3.15-4.90 pmol/l, sRANKL at 0.20-0.60 pmol/l, and the OPG/RANKL ratio at 7.40-20.00. Serum OPG, sRANKL and OPG/RANKL levels did not change significantly with gender, BMI and Tanner stage of puberty. A statistically significant negative correlation was found between age and OPG levels (r = -0.32, p = 0.0168) and OPG/RANKL ratio (r = -0.34, p = 0.0228). CONCLUSIONS:In healthy children and adolescents, OPG levels decrease with age, but the influence of puberty and body weight on OPG and sRANKL levels requires further investigation.

Introduction and objective: Osteogenesis imperfecta is a heritable bone dysplasia resulting in reduced bone mineral density. Fractures of long bones, which are the dominant symptom of osteogenesis imperfecta, can be diagnosed already in foetal life. Multiple fractures are associated with severe pain, which may cause deterioration of the newborn’s general condition, respiratory and circulatory disorders, and reduced general motor activity. The aim of the study was to summarise the experience resulting from many years of care and treatment of neonates with osteogenesis imperfecta types II and III. Materials and methods: The study included 53 newborns with osteogenesis imperfecta hospitalised at the Department of Paediatrics, Newborn Pathology and Bone Metabolic Diseases in the years 2001–2021. All children underwent a babygram and an assessment of their health status, including calcium and phosphorus metabolism parameters. Results: In 67.3% of cases, the mother was informed before delivery that she would give birth to a sick child. The general condition of the newborns was moderately severe to severe in 43.4%. Physical examination revealed abnormal body proportions related to previous fractures in 98.1% of patients, including long bones of limbs. More than 10 fresh bone fractures were diagnosed in 34% of children. Conclusions: Prenatal diagnosis of osteogenesis imperfecta indicates its severe course (multiple fractures) in the neonatal period. Therefore, it requires care in a specialised centre that will provide safe, symptomatic pharmacological treatment (bisphosphonates) to reduce both pain and the risk of further bone fractures.

Osteogenesis imperfecta (OI) is a rare genetic disorder of the connective tissue. It presents with a wide spectrum of skeletal and extraskeletal features, and ranges in severity from mild to perinatal lethal. The disease is characterized by a heterogeneous genetic background, where approximately 85%–90% of cases have dominantly inherited heterozygous pathogenic variants located in the COL1A1 and COL1A2 genes. This paper presents the results of the first nationwide study, performed on a large cohort of 197 Polish OI patients. Variants were identified using a next-generation sequencing (NGS) custom gene panel and multiplex ligation probe amplification (MLPA) assay. The following OI types were observed: 1 (42%), 2 (3%), 3 (35%), and 4 (20%). Collagen type I pathogenic variants were reported in 108 families. Alterations were observed in α1 and α2 in 70% and 30% of cases, respectively. The presented paper reports 97 distinct causative variants and expands the OI database with 38 novel pathogenic changes. It also enabled the identification of the first glycine-to-tryptophan substitution in the COL1A1 gene and brought new insights into the clinical severity associated with variants localized in “lethal regions”. Our results contribute to a better understanding of the clinical and genetic aspects of OI.

AbstractBackgroundOsteogenesis imperfecta (OI) is a genetic disorder of connective tissue with variable phenotype and heterogeneous genetic background. Majority of reported mutations are glycine substitutions, whose clinical outcome ranges from mild to perinatal lethal. The phenotype appears to be influenced by the properties of amino acid side chain and the degree of structural aberration of collagen molecules. Since the genotype–phenotype correlation remains unclear, the severity of mutation is mostly predicted according to previously‐reported cases. Although the number of OI variants is constantly expanding, no glycine‐to‐tryptophan substitutions have been reported in COL1A1 gene.MethodsA sample from a 15‐year‐old girl presenting with progressively‐deforming OI type III was tested using an NGS custom gene panel. Multiple bioinformatic and interpretation tools, including mutation databases and conservation analysis, were used for variant classification. The presence of the mutation was verified by Sanger sequencing.ResultsA novel heterozygous mutation c.733G>T was identified in the COL1A1 gene (p.Gly245Trp).ConclusionsThe discovery of this novel glycine‐to‐tryptophan substitution located in the COL1A1 gene broadens the spectrum of mutations underlying this rare disease and provides useful information on the clinical outcome of such substitutions.

Hypophosphatemic rickets is a rare disease that results in bone deformities. However, little is known about bone turnover and bone mass disorders in this disease. This retrospective study included 12 children aged 1–16 years diagnosed with hypophosphatemic rickets. Parameters of calcium-phosphate metabolism and bone turnover markers were analysed. Bone mineral density was assessed with the use of dual-energy X-ray absorptiometry, and indices of quantitative ultrasound examination of tibiae and radial bones were analysed. In the majority of patients, hypophosphatemia and hyperphosphaturia were present. The assessed bone turnover markers showed increased bone formation. Increased pyridinoline levels were found in 5 out of 12 patients. Bone mineral density was decreased only in one patient. Decreased values of quantitative ultrasound examination were observed in all the analysed patients. Conclusions: (1) Bone metabolism disturbances, reflected in the increased values of bone turnover markers and worse bone quality, were found in the group of patients with hypophosphatemic rickets. (2) It is crucial to determine bone turnover markers, dual-energy X-ray absorptiometry findings and indices of quantitative ultrasound examination in order to monitor progress of the disease, as well as treatment effects.

Osteogenesis imperfecta (OI) is a rare genetic disorder demonstrating considerable phenotypic and genetic heterogeneity. The extensively studied genotype–phenotype correlation is a crucial issue for a reliable counseling, as the disease is recognized at increasingly earlier stages of life, including prenatal period. Based on population studies, clusters in COL1A1 and COL1A2 genes associated with the presence of glycine substitutions leading to fatal outcome have been distinguished and named as “lethal regions.” Their localization corresponds to the ligand-binding sites responsible for extracellular interactions of collagen molecules, which could explain high mortality associated with mutations mapping to these regions. Although a number of non-lethal cases have been identified from the variants located in lethal clusters, the mortality rate of mutations has not been updated. An next generation sequencing analysis, using a custom gene panel of known and candidate OI genes, was performed on a group of 166 OI patients and revealed seven individuals with a causative mutations located in the lethal regions. Patients’ age, ranging between 3 and 25 years, excluded the expected fatal outcome. The identification of non-lethal cases caused by mutations located in lethal domains prompted us to determine the actual mortality caused by glycine substitutions mapping to lethal clusters and evaluate the distribution of all lethal glycine mutations across collagen type I genes, based on records deposited in the OI Variant Database. Finally, we identified six glycine substitutions located in lethal regions of COL1A1 and COL1A2 genes, of which four are novel. The review of all mutations in the dedicated OI database, revealed 33 distinct glycine substitutions in two lethal domains of COL1A1, 26 of which have been associated with a fatal outcome. Similarly, 109 glycine substitutions have been identified in eight lethal clusters of COL1A2, of which 51 have been associated with a fatal manifestation. An analysis of all glycine substitutions leading to fatal phenotype, showed that their distribution along collagen type I genes is not regular, with 17% (26 out of 154) of mutations reported in COL1A1 and 64% (51 out of 80) in COL1A2 corresponding to localization of the lethal regions.

INTRODUCTION:Type 1 diabetes (T1D) may be associated with numerous complications including bone metabolism disorders. The aim of the study was to evaluate the bone metabolism markers twice in children with a newly diagnosed T1D and after an average of seven months of its duration in relation to parameters of the clinical course of diabetes.MATERIAL AND METHODS:In 100 T1D patients and 52 control subjects, the following bone turnover markers were evaluated: osteocalcin - OC, osteoprotegerin - OPG, sRANKL, and deoxypyridoline in urine - DPD and DXA examination was also performed.RESULTS:Lower OC concentration at T1D onset in comparison to controls (p < 0.001) and its increase during follow-up (p < 0.001) was ob-served. The OPG concentration was elevated at T1D onset as compared to the control group (p = 0.024) and decreased thereafter (p < 0.001). The s-RANKL level increased during follow-up (p < 0.001) and was lower than in controls (p < 0.001). Urine DPD con-centration also increased during follow-up in the T1D patient group (p < 0.001) and was higher in comparison to the control group (p = 0.021). BMD-TBLH was higher in the control group as compared to patients both at T1D onset (p = 0.025) and in follow-up ob-servation (p = 0.034). Moreover, OPG correlated positively with glycated haemoglobin (HbA1c) (p = 0.004) and negatively with fasting C-peptide level (p = 0.046) and BMI Z-score (p = 0.003), whereas s-RANKL correlated positively with both fasting (p < 0.001) and stimulated C-peptide levels (p < 0.001).CONCLUSIONS:Bone metabolism disorders observed at T1D onset in children and modified after reaching the metabolic control of the disease seem to be most strongly associated with preserved insulin secretion.

Introduction. Osteogenesis imperfecta is an inherited disorder of the connective tissue. Which in most cases, is caused by mutations in the genes encoding collagen type I. Apart from clinical features, there are characteristic dental aberrations. Aim. The purpose of this research was the assessment of the condition of teeth and therapeutic needs of children with the congenital brittle bone disease. Material and methods. The questionnaires with patient’s parents, consisting medical history and dental history were performed. The intra-oral examination included the condition of the dentition, the presence of dentinogenesis imperfecta, malocclusion, the assessment of the attrition index and dmft/DMFT index. Results. 62 patients with osteogenesis imperfecta were examined – 32 boys and 30 girls. There were normal eruption times of deciduous (48 patients – 77.42%) and permanent teeth (34 patients – 82.93%) reported in the majority of the patients with OI. In most cases bad eating and hygienic habits were observed. Dentinogenesis imperfecta in deciduous and permanent teeth was reported mostly in type III of OI. dmft/DMFT index among children with OI were low in comparison to the population studies of corresponding age groups. Conclusions. Despite bad eating and hygienic habits as well as pathological structure of dentition of patients with the congenital brittle bone disease, caries index among these children were low in comparison to the population studies of corresponding age groups.

Introduction: Type 1 neurofibromatosis (NF1) belongs to the group of phacomatoses characterised by the formation of neurofibromas in the course of the nerves. In some cases, it may also lead to lesser known skeletal symptoms such as disturbances in calcium-phosphate metabolism and decreased bone mineral density. Aim of the study: The purpose of this work is to analyse possible skeletal complications in the course of neurofibromatosis, based on presentation of patients with NF1. Material and methods: The study included 10 children diagnosed with NF1 (seven girls and three boys), aged four to 17 years. Medical examinations including evaluation of any motor system abnormalities, anthropometric measurements of body height and weight (to evaluate the respective parameters, centile charts were used from the OLAF project), and bone densitometry using dual-energy X-ray absorptiometry (DXA) were performed. Calcium and phosphate metabolisms were assessed based on laboratory tests (concentration of vitamin D – 25(OH)D, parathormone and alkaline phosphatase levels, and bone turnover markers). Results: Decreased body height was found in half of the patients (5/10). Typical dysplastic bone lesions were observed in 3/10 children. On densitometry, in nine out of 10 examined children a Z-score decrease to < –1.0 was observed, and in five children this value was ≤ –2.0. Decreased 25(OH)D concentration was found in 7/10 examined children. In three out of 10 patients the osteocalcin level was increased. Conclusions: NF1 may jeopardise normal development and function of the skeletal system in children – both of the mineral and bone metabolism. Assessment of the motor system and of the calcium and phosphate metabolism should be part of extended diagnosis and monitoring of this disease. Risk factors for bone fractures in children with NF1 are low bone mass and decreased vitamin D concentration.

Searchable abstracts of presentations at key conferences on calcified tissues ISSN 2052-1219 (online)

BACKGROUND:Low bone mineral density is a common finding in children with systemic connective tissue diseases, including juvenile idiopathic arthritis (JIA). The influence of the ongoing process of bone remodeling on the disease course merits further investigation. The aim of this study was to assess the clinical relevance of markers of bone turnover and their potential role as predictors of higher fracture risk and, by extension, risk of osteoporosis.MATERIALS AND METHODS:Blood samples were collected from 59 patients diagnosed with JIA in order to determine serum levels of the following markers of bone turnover: Beta-Crosslaps, osteocalcin, bone alkaline phosphatase, osteoprotegerin and receptor activator for nuclear factor kappa-B ligand. The values were analyzed with laboratory parameters and results of dual X-ray absorptiometry (DXA).RESULTS:Osteoprotegerin and bone alkaline phosphatase levels were age-dependent. Beta-Crosslaps values were significantly higher in patients with positive JADAS27 score (p=0.0410). Osteoprotegerin levels were higher in patients treated with biological agents than only with disease-modifying anti-rheumatic drugs (p=0.0273). There was no relation between markers of bone turnover and sex, DXA results, dosage of glucocorticosteroids and disease duration.CONCLUSIONS:The authors postulate performing DXA measurements every 6 months in patients with higher disease activity. The potential lower fracture risk in children with JIA within biological treatment needs further assessment. Age- and sex-adjusted reference rates of bone turnover markers need to be developed for Central European patients in order to assess individual values properly.

INTRODUCTION:Vitamin D deficiency is an important public health problem worldwide. Vitamin D deficiency confers a significant risk for both skeletal and non-skeletal disorders and a number of lifelong negative health outcomes. The objectives of this evidence-based guidelines document are to provide health care professionals in Poland, an updated recommendation for the prevention, diagnosis and treatment of vitamin D deficiency.METHODS:A systematic literature search examining the prevention and treatment strategies for vitamin D deficiency was conducted. Updated recommendations were developed using the Grading of Recommendations, Assessment, Development and Evaluation system describing the strength of the recommendation and the quality of supporting evidence. Twenty-seven contributors representing different areas of expertise and medical specialties, including pediatricians, geriatricians, endocrinologists, epidemiologists, nephrologists, gynecologists and obstetricians evaluated the available published evidence related to vitamin D, formulated the goals of this document and developed a common consolidated position. The consensus group, representing six national specialist consultants and eight Polish and international scientific organizations/societies, participated in the process of grading evidence and drawing up the general and specific recommendations.RESULTS:The updated recommendations define the diagnostic criteria for the evaluation of vitamin D status and describe the prevention and treatment strategies of vitamin D deficiency in the general population and in groups at increased risk of the deficiency. Age- and weight-specific recommendations for prevention, supplementation and treatment of vitamin D deficiency are presented, and detailed practice guidance is discussed regarding the management in primary and specialized health care.CONCLUSION:Vitamin D deficiency remains still highly prevalent in Poland, in all age groups. Currently, there is a great necessity to implement a regular supplementation with recommended doses and to develop an effective strategy to alleviate vitamin D deficiency in the population. These updated recommendations are addressed to health professionals and the authorities pursuing comprehensive health policies and should also be included in public health programs aimed at preventing a broad spectrum of chronic diseases.

To evaluate the extent to which the population of Polish preadolescents is vitamin D deficient and to assess seasonal variations in vitamin D status.

BACKGROUND:Childhood solar ultraviolet radiation (UVR) exposure increases the risk of skin cancer in adulthood, which is associated with mutations caused by UVR-induced cyclobutane pyrimidine dimers (CPD). Solar UVR is also the main source of vitamin D, essential for healthy bone development in children.OBJECTIVES:To assess the impact of a 12-day Baltic Sea (54° N) beach holiday on serum 25-hydroxyvitamin D3 [25(OH)D3 ] and CPD in 32 healthy Polish children (skin types I-IV).METHODS:Blood and urine were collected before and after the holiday and assessed for 25(OH)D3 and excreted CPD, respectively, and personal UVR exposure was measured. Diaries were used to record sunbathing, sunburn and sunscreen use. Before- and after-holiday skin redness and pigmentation were measured by reflectance spectroscopy.RESULTS:The average ± SD daily exposure UVR dose was 2·4 ± 1·5 standard erythema doses (SEDs), which is borderline erythemal. The mean concentration of 25(OH)D3 increased (× 1·24 ± 0·19) from 64·7 ± 13·3 to 79·3 ± 18·7 nmol L-1 (P < 0·001). Mean CPD increased 12·6 ± 10·0-fold from 26·9 ± 17·9 to 248·9 ± 113·4 fmol μmol-1 creatinine (P < 0·001). Increased 25(OH)D3 was accompanied by a very much greater increase in DNA damage associated with carcinogenic potential. Overall, skin type had no significant effects on behavioural, clinical or analytical outcomes, but skin types I/II had more CPD (unadjusted P = 0·0496) than skin types III/IV at the end of the holiday.CONCLUSIONS:Careful consideration must be given to the health outcomes of childhood solar exposure, and a much better understanding of the risk-benefit relationships of such exposure is required. Rigorous photoprotection is necessary for children, even in Northern Europe.

Searchable abstracts of presentations at key conferences on calcified tissues ISSN 2052-1219 (online)

Searchable abstracts of presentations at key conferences on calcified tissues ISSN 2052-1219 (online)