[Analysis of clinical presentation and genetic characteristics of malignant infantile osteopetrosis].

Objective: To investigate the clinical presentation and genetic characteristics of malignant infantile osteopetrosis. Methods: This was a retrospective case study. Thirty-seven children with malignant infantile osteopetrosis admitted into Beijing Children's Hospital from January 2013 to September 2022 were enrolled in this study. According to the gene mutations, the patients were divided into the CLCN7 group and the TCIRG1 group. Clinical characteristics, laboratory tests, and prognosis were compared between two groups. Wilcoxon test or Fisher exact test were used in inter-group comparison. The survival rate was estimated with the Kaplan-Meier method and the Log-Rank test was used to compare the difference in survival between groups. Results: Among the 37 cases, there were 22 males and 15 females. The age of diagnosis was 0.5 (0.2, 1.0) year. There were 13 patients (35%) and 24 patients (65%) with mutations in CLCN7 and TCIRGI gene respectively. Patients in the CLCN7 group had an older age of diagnosis than those in the TCIRGI group (1.2 (0.4, 3.6) vs. 0.4 (0.2, 0.6) years, Z=-2.60, P=0.008). The levels of serum phosphorus (1.7 (1.3, 1.8) vs. 1.1 (0.8, 1.6) mmol/L, Z=-2.59, P=0.010), creatine kinase isoenzyme (CK-MB) (457 (143, 610) vs. 56 (37, 82) U/L, Z=-3.38, P=0.001) and the level of neutrophils (14.0 (9.9, 18.1) vs. 9.2 (6.7, 11.1) ×109/L, Z=-2.07, P=0.039) at diagnosis were higher in the CLCN7 group than that in the TCIRG1 group. However, the level of D-dimer in the CLCN7 group was lower than that in the TCIRGI group (2.7 (1.0, 3.1) vs. 6.3 (2.5, 9.7) µg/L, Z=2.83, P=0.005). After hematopoietic stem cell transplantation, there was no significant difference in 5-year overall survival rate between the two groups (92.3%±7.4% vs. 83.3%±7.6%, χ²=0.56, P=0.456). Conclusions: TCIRGI gene mutations are more common in children with osteopetrosis. Children with TCIRGI gene mutations have younger age, lower levels of phosphorus, CK-MB, and neutrophils and higher level of D-dimer at the onset. After hematopoietic stem cell transplantation, patients with CLCN7 or TCIRGI gene mutations have similar prognosis.

Severe hypophosphataemia can be an early sign of osteopetrorickets: a case report.

Osteopetrorickets is a rare complication of autosomal recessive ("malignant") osteopetrosis. Its prompt diagnosis is essential, because early suspicion of infantile osteopetrosis enables treatment with human stem cell transplantation, depending on the gene involved. It is important to identify not only the characteristic radiological changes of rickets, but also the coexistence of increased bone density, so as not to miss this very rare entity. Herein, a brief case report is presented.

Clinical and Osteopetrosis-Like Radiological Findings in Patients with Leukocyte Adhesion Deficiency Type III.

BACKGROUND: Leukocyte and platelet integrin function defects are present in leukocyte adhesion deficiency type III (LAD-III) due to mutations in FERMT3. Additionally, osteoclast/osteoblast dysfunction develops in LAD-III. AIM: To discuss the distinguishing clinical, radiological, and laboratory features of LAD-III. METHODS: This study included the clinical, radiological, and laboratory characteristics of twelve LAD-III patients. RESULTS: The male/female ratio was 8/4. The parental consanguinity ratio was 100%. Half of the patients had a family history of patients with similar findings. The median age at presentation and diagnosis was 18 (1-60) days and 6 (1-20) months, respectively. The median leukocyte count on admission was 43,150 (30,900-75,700)/µL. The absolute eosinophil count was tested in 8/12 patients, and eosinophilia was found in 6/8 (75%). All patients had a history of sepsis. Other severe infections were pneumonia (66.6%), omphalitis (25%), osteomyelitis (16.6%), gingivitis/periodontitis (16%), chorioretinitis (8.3%), otitis media (8.3%), diarrhea (8.3%), and palpebral conjunctiva infection (8.3%). Four patients (33.3%) received hematopoietic stem cell transplantation (HSCT) from HLA-matched-related donors, and one deceased after HSCT. At initial presentation, 4 (33.3%) patients were diagnosed with other hematologic disorders, three patients (P5, P7, and P8) with juvenile myelomonocytic leukemia (JMML), and one (P2) with myelodysplastic syndrome (MDS). CONCLUSION: In LAD-III, leukocytosis, eosinophilia, and bone marrow findings may mimic pathologies such as JMML and MDS. In addition to non-purulent infection susceptibility, patients with LAD-III exhibit Glanzmann-type bleeding disorder. In LAD-III, absent integrin activation due to kindlin-3 deficiency disrupts osteoclast actin cytoskeleton organization. This results in defective bone resorption and osteopetrosis-like radiological changes. These are distinctive features compared to other LAD types.

The clinical features of OSTM1-associated malignant infantile osteopetrosis: A retrospective, single-center experience over one decade.

Mutation in OSTM1 give rise to the rarest and most lethal subtype of malignant infantile osteopetrosis (MIOP), and an improved understanding of OSTM1-associated MIOP would help with informed decision-making regarding symptom management and early palliative care referral. This retrospective study describes the clinical and laboratory features of patients with a genetic diagnosis of OSTM1 MIOP made between January 2011 and December 2021 in the Department of Pediatrics, Al-Adan Hospital, Kuwait. Twenty-two children had confirmed homozygous deletion in OSTM1 (13 females, nine males). Consanguinity was reported in almost all parents. 72.7% were diagnosed before the age of two months, most commonly incidentally with a high clinical suspicion. All 22 patients developed upper respiratory symptoms, hepatosplenomegaly, poor feeding, and had severe developmental delay. 80% of patients developed pain and/or irritability, and 40.9% were diagnosed with primary seizures. Bone fractures developed in 27% of patients, most likely iatrogenic, and some patients had hernia and gum abnormalities. The mean survival was 10.9 months. The clinical presentation, symptomatology, and mortality of our cohort were compared with other cases of OSTM1 MIOP identified through a comperhensive search of the PubMed database. The findings conclude that OSTM1 MIOP is a multi-systemic disease with distinct clinical features, of which neurological complications are the most severe and include nociplastic pain and irritability. Although orthopedic complications influence the trajectory of most patients with other forms of osteopetrosis, OSTM1 MIOP is driven by its neurological complications. Hence, OSTM1 should be regarded as a neurodegenerative disease with osteopetrosis as a comorbidity that warrants early palliative care referral.

Malignant infantile osteopetrosis in a 3-year-old Yemeni child: a case report.

Infantile malignant osteopetrosis (IMOP) is a rare bone resorptive disorder with an autosomal recessive inheritance pattern. It is characterized by increased bone density due to osteoclastic failure in differentiation or function. The clinical manifestations of IMOP start at birth or infancy with varied rings according to the type and degree of osteopetrosis. We presented a 3-year-old female patient referred to us due to chronic anaemia six months ago. The physical examination revealed hepatosplenomegaly, axial hypotonia, and visual impairment. Blood investigation revealed pancytopenia and hypocalcemia. Radiologic studies revealed a generalized increase in bone density, abnormal metaphyseal remodelling, and rain atrophy. The bone marrow aspiration (BMA) shows dry tap and hypocellularity of all cell lines. IMOP was diagnosed depending on clinical, radiologic, and BMA results. In conclusion, IMOP is relatively uncommon. Accurate diagnosis should be made through clinical, BMA, and radiologic investigations, especially in a resource-limited setting, as performed in our case.

Malignant Infantile Osteopetrosis with Bone Marrow Involvement.

Osteopetrosis (Marble bone disease) is a very rare congenital genetic disease of skeleton, resulting from defective bone resorption, due to functionally defective osteoclast, leading to accumulation of excessive bone mass. Malignant infantile osteopetrosis (MIO) is one of the varieties of osteopetrosis, which is fatal and is diagnosed in early infancy. Malignant infantile osteopetrosis is present with abnormal bone remodeling, hematological abnormities, features of extramedullary hematopoiesis. Radiology is the key of diagnosis. In this case, we present a 5-monthold male infant diagnosed as malignant infantile osteopetrosis, who presented with bronchopneumonia, anemia, thrombocytopenia, hepatosplenomegaly, failure to thrive (FTT).

Case report of mild TCIRG1-associated autosomal recessive osteopetrosis in Vietnam.

Autosomal recessive osteopetrosis (ARO) is a group of disease characterized by osteoclast dysfunction inhibiting bone resorption and bone turnover, with TCIRG1-associated ARO being more common leading to autosomal recessive infantile malignant osteopetrosis (OPTB1, MIM entry number # 259700). While most patients with TCIRG1-associated osteopetrosis present a malignant clinical course and shortened lifespan, a few cases of non-malignant TCIRG1-associated osteopetrosis have been reported. 24-year-old female patient came to us with limp gait, hip pain in both sides, and severe stiffness. She had suffered many fractures, bilateral hip osteoarthritis, right leg was 2 cm shorter compared with left leg. Whole Exome Sequencing was conducted, the result and subsequent Sanger's sequencing shown the patient had a compound heterozygous genotype at TCIRG1 (c.1194dup, p.Gly399ArgTer and c.334G>A, p.Gly112Arg), these two variants found were not previously reported. Sanger's sequencing revealed two other siblings whom suffer the same disorder had similar genotype to the proband; the parents were found to be heterozygous. This is the first case of TCIRG1-associated osteopetrosis reported in Vietnam and one of the few cases of nonmalignant TCIRG1-associated osteopetrosis, in which detailed clinical and genetic work-up were performed.

Findings on Optical Coherence Tomography in Malignant Infantile Osteopetrosis.

Malignant infantile osteopetrosis is a rare inherited disorder with neurological complications and a shortened life expectancy. Vision loss is typically attributed to osseous compression of the optic nerves at the level of the optic canal. Fundus imaging is reported, as well as the first optical coherence tomography and optical coherence tomography angiography in this rare condition. Imaging revealed optic nerve pallor, subfoveal ellipsoid zone disruption, and an enlarged foveal avascular zone. These results provide insight regarding other potential mechanisms of vision loss in these patients. [Ophthalmic Surg Lasers Imaging Retina 2022; 53:398-402.].

A Mild Case of Autosomal Recessive Osteopetrosis Masquerading as the Dominant Form Involving Homozygous Deep Intronic Variations in the CLCN7 Gene.

Osteopetrosis is a heterogeneous group of rare hereditary diseases characterized by increased bone mass of poor quality. Autosomal-dominant osteopetrosis type II (ADOII) is most often caused by mutation of the CLCN7 gene leading to impaired bone resorption. Autosomal recessive osteopetrosis (ARO) is a more severe form and is frequently accompanied by additional morbidities. We report an adult male presenting with classical clinical and radiological features of ADOII. Genetic analyses showed no amino-acid-converting mutation in CLCN7 but an apparent haploinsufficiency and suppression of CLCN7 mRNA levels in peripheral blood mononuclear cells. Next generation sequencing revealed low-frequency intronic homozygous variations in CLCN7, suggesting recessive inheritance. In silico analysis of an intronic duplication c.595-120_595-86dup revealed additional binding sites for Serine- and Arginine-rich Splicing Factors (SRSF), which is predicted to impair CLCN7 expression. Quantitative backscattered electron imaging and histomorphometric analyses revealed bone tissue and material abnormalities. Giant osteoclasts were present and additionally to lamellar bone, and abundant woven bone and mineralized cartilage were observed, together with increased frequency and thickness of cement lines. Bone mineralization density distribution (BMDD) analysis revealed markedly increased average mineral content of the dense bone (CaMean T-score + 10.1) and frequency of bone with highest mineral content (CaHigh T-score + 19.6), suggesting continued mineral accumulation and lack of bone remodelling. Osteocyte lacunae sections (OLS) characteristics were unremarkable except for an unusually circular shape. Together, our findings suggest that the reduced expression of CLCN7 mRNA in osteoclasts, and possibly also osteocytes, causes poorly remodelled bone with abnormal bone matrix with high mineral content. This together with the lack of adequate bone repair mechanisms makes the material brittle and prone to fracture. While the skeletal phenotype and medical history were suggestive of ADOII, genetic analysis revealed that this is a possible mild case of ARO due to deep intronic mutation.

A cross-sectional nationwide survey of osteosclerotic skeletal dysplasias in Japan.

BACKGROUND: The osteosclerotic skeletal dysplasias (OSSDs) are a heterogeneous group of disorders characterized by systemic bone sclerosis. Little is known about OSSDs because of their rarity. We conducted a cross-sectional nationwide survey of OSSDs and examined the incidence, epidemiology, and therapeutic interventions on these disorders. METHODS: This study consisted of a two-step survey. The number of patients with OSSDs who had visited medical institutions between April 2017 and March 2018 was reported from a total of 341 facilities (1364 departments from pediatrics, orthopaedic surgery, neurosurgery, and otolaryngology in each facility) by the first questionnaire. In the secondary survey, their clinical features were assessed by collecting demographic data, diagnostic details, current status, family histories, therapeutic interventions, histories of bone fracture and osteomyelitis, severity assessed by the modified Rankin Scale (mRS) and recent lifestyle conditions of the patient by the EQ-5D. RESULTS: In the first survey, 51 facilities (56 departments) reported one or more OSSDs patients, including 50 patients with osteopetrosis and 57 patients of other OSSDs. Among 87 patients eligible for inclusion in the analysis in the secondary survey, we investigated detailed information on the 42 patients with osteopetrosis. The number of initial visits of osteopetrosis patients during the surveillance period was five per year, indicating that the estimated incidence of osteopetrosis seemed to be 0.6 per 100,000 live births. Eighty-six bone fractures were reported in 22 patients (52%), and interventions of pseudarthrosis were conducted in five patients. Nine patients (23%) showed significant disabilities with the mRS of grade 3 or higher. Neurological complications and severe anemia were the factors that deteriorate patients' quality of life. CONCLUSIONS: This is the first study to examine the detailed epidemiology of OSSDs in Japan. We demonstrated that the incidence of OSSDs is extremely rare. Bone fragility and delayed fracture healing seem to be important orthopaedic problems for patients with osteopetrosis.

Osteopetrosis autosómica dominante benigna: Reporte de caso / Autosomal dominant osteopetrosis: Case report

La osteopetrosis es una enfermedad infrecuente, se caracteriza por el incremento de la densidad ósea observada en las radiografías, resultado de anormalidades en la diferen- ciación y función de los osteoclastos que les incapacita para la resorción ósea y cartilaginosa, formándose huesos más densos, pero más frágiles. Objetivo: describir la Osteopetrosis Auto- sómica Dominante mostrando nuestra experiencia el método de tratamiento. Con un amplio conocimiento de esta patología, los hallazgos radiográficos característicos y los manejos tera- péuticos adecuados podremos lograr un diagnóstico precoz certero y una mejor sobrevida de los pacientes. Reporte de caso: Paciente femenina de 13 años, con historia de fracturas espontáneas a repetición en los antebrazos principalmente, la madre niega antecedentes de trauma; asimismo refiere observar retraso en el crecimiento de la paciente, por lo cual acude al hospital regional de occidente, Quetzaltenango, Guatemala, para evaluación. Se le realizan radiografías en proyección anteroposterior (AP) y lateral de cráneo, de extremidades superio- res e inferiores y de columna dorsal evidenciando en las radiografías de cráneo aumento de la densidad ósea y aumento de grosor de la misma, en la columna dorsal se observó aumento de la esclerosis a nivel de las placas terminales superiores e inferiores de los cuerpos vertebrales, dando la típica apariencia de "vertebra en sándwich", signo patognomónico de esta enferme- dad. La paciente recibió tratamiento con prednisolona, vitamina D y calcio en dosis de acuerdo a las medidas antropométricas de la paciente y control médico por año para evaluar estado clínico...(AU)

Brain Abscess in a Patient with Osteopetrosis: A Rare Complication

Brain abscess formation is extremely rare in patients with osteopetrosis. Herein, we report a case of viridans streptococci brain abscess in an immunocompromised child diagnosed with osteopetrosis. The patient presented with a sudden change in mental status and convulsions. Radiological evaluation revealed a temporal lobe brain abscess, and intravenous antibiotherapy was started immediately. The patient underwent abscess drainage, and laboratory investigation of pus material revealed viridans streptococci.

A Homozygous Mutation in 5' Untranslated Region of TNFRSF11A Leading to Molecular Diagnosis of Osteopetrosis Coinheritance With Wiskott-Aldrich Syndrome.

Wiskott-Aldrich syndrome (WAS) and osteopetrosis are 2 different, rare hereditary diseases. Here we report clinical and molecular genetics investigations on an infant patient with persistent thrombocytopenia and prolonged fever. He was clinical diagnosed as osteopetrosis according to clinical presentation, radiologic skeletal features, and bone biopsy results. Gene sequencing demonstrated a de novo homozygous mutation in 5'-untranslated region of TNFRSF11A, c.-45A>G, which is relating to osteopetrosis. Meanwhile, a hemizygous transition mutation in WAS gene, c.400G>A diagnosed the infant with WAS. This is the first clinical report for the diagnosis of osteopetrosis coinheritance with WAS in a single patient.

Pleomorphic Sarcoma in a Patient with Osteopetrosis.

Osteopetrosis comprises a rare, heterogeneous group of heritable conditions that are characterized by a defect in bone resorption by osteoclasts. We report the case of a 53-year-old woman with previously undiagnosed osteopetrosis who presented with a pathologic proximal humeral fracture secondary to pleomorphic sarcoma, which is previously undescribed in the English literature. Management of the primary lesion necessitated ablative surgery, but the malignancy nonetheless was associated with rapidly progressive metastatic disease.

A Clinical Perspective on Advanced Developments in Bone Biopsy Assessment in Rare Bone Disorders.

Introduction: Bone biopsies have been obtained for many centuries and are one of the oldest known medical procedures in history. Despite the introduction of new noninvasive radiographic imaging techniques and genetic analyses, bone biopsies are still valuable in the diagnosis of bone diseases. Advanced techniques for the assessment of bone quality in bone biopsies, which have emerged during the last decades, allows in-depth tissue analyses beyond structural changes visible in bone histology. In this review, we give an overview of the application and advantages of the advanced techniques for the analysis of bone biopsies in the clinical setting of various rare metabolic bone diseases. Method: A systematic literature search on rare metabolic bone diseases and analyzing techniques of bone biopsies was performed in PubMed up to 2019 week 34. Results: Advanced techniques for the analysis of bone biopsies were described for rare metabolic bone disorders including Paget's disease of bone, osteogenesis imperfecta, fibrous dysplasia, Fibrodysplasia ossificans progressiva, PLS3 X-linked osteoporosis, Loeys-Diets syndrome, osteopetrosis, Erdheim-Chester disease, and Cherubism. A variety of advanced available analytical techniques were identified that may help to provide additional detail on cellular, structural, and compositional characteristics in rare bone diseases complementing classical histopathology. Discussion: To date, these techniques have only been used in research and not in daily clinical practice. Clinical application of bone quality assessment techniques depends upon several aspects such as availability of the technique in hospitals, the existence of reference data, and a cooperative network of researchers and clinicians. The evaluation of rare metabolic bone disorders requires a repertoire of different methods, owing to their distinct bone tissue characteristics. The broader use of bone material obtained from biopsies could provide much more information about pathophysiology or treatment options and establish bone biopsies as a valuable tool in rare metabolic bone diseases.

Transcriptome sequencing identifies a noncoding, deep intronic variant in CLCN7 causing autosomal recessive osteopetrosis.

BACKGROUND: Over half of children with rare genetic diseases remain undiagnosed despite maximal clinical evaluation and DNA-based genetic testing. As part of an Undiagnosed Diseases Program applying transcriptome (RNA) sequencing to identify the causes of these unsolved cases, we studied a child with severe infantile osteopetrosis leading to cranial nerve palsies, bone deformities, and bone marrow failure, for whom whole-genome sequencing was nondiagnostic. METHODS: We performed transcriptome (RNA) sequencing of whole blood followed by analysis of aberrant transcript isoforms and osteoclast functional studies. RESULTS: We identified a pathogenic deep intronic variant in CLCN7 creating an unexpected, frameshifting pseudoexon causing complete loss of function. Functional studies, including osteoclastogenesis and bone resorption assays, confirmed normal osteoclast differentiation but loss of osteoclast function. CONCLUSION: This is the first report of a pathogenic deep intronic variant in CLCN7, and our approach provides a model for systematic identification of noncoding variants causing osteopetrosis-a disease for which molecular-genetic diagnosis can be pivotal for potentially curative hematopoietic stem cell transplantation. Our work illustrates that cryptic splice variants may elude DNA-only sequencing and supports broad first-line use of transcriptome sequencing for children with undiagnosed diseases.

Extensive maxillary osteomyelitis following tooth extraction in a patient with osteopetrosis.

Osteopetrosis (OP), also known as marble bone disease is an extremely rare inherited skeletal disorder, characterised by abnormal functioning of the osteoclasts that results in incremental bone deposition with lack of normal bone remodelling. This leads to the formation of hard and brittle bone can readily fracture. The compromised quality of marrow tissue with poor vascularity reduces bone healing and increases the risk of infections. The risk of jawbone osteomyelitis in patients with OP is high and invariably involves mandible. Involvement of maxilla is rare and has been sparingly reported in the literature. This paper highlights a case of extensive necrosis of maxilla and mid-face skeleton following tooth extraction in a patient with OP. Review of the English literature identifying 23 previously published reports of maxillary osteomyelitis in patients with OP is also presented. Demographic details, history of tooth extraction, extent of involvement, clinical presentation, imaging finding, treatment provided and the outcome have been discussed.

Malignant Infantile osteopetrosis. / Osteopetrosis infantil maligna.

INTRODUCTION: Malignant Infantile Osteopetrosis (MIOP) is a rare and severe genetic disorder due to abnormal osteoclast activity. OBJECTIVE: To report an infant who presented Malignant Infantile Osteopetrosis, reviewing the most relevant diagnostic and therapeutic aspects. CLINICAL CASE: A ten- month-old male infant with diagnosis of MIOP confirmed after presenting thrombocytopenia and visceromegaly. He was the first child of non-consanguineous parents, and among the findings, he presented severe hepatosplenomegaly, thrombocytopenia, and anemia; visual and hearing impair ment, and repeated infections. The diagnosis was confirmed by genetic study, which identified two heterozygous mutations in the TCIRG1 gene. Hematopoietic stem cells were transplanted without hematological recovery. The patient died due to occlusive venous disease. DISCUSSION: MIOP is a rare, severe, and early-onset disease, with a high rate of suspicion necessary in the presence of hepa- tosplenomegaly and bone marrow failure. Early diagnosis and hematopoietic stem cells transplanta tion are the only potentially therapeutic interventions of this lethal entity.