BACKGROUND Osteopetrosis is a rare genetic disorder characterized by increased bone density due to defective bone resorption of osteoclasts.Approximately,80%of autosomal dominant osteopetrosis type II(ADO-II)patients ...BACKGROUND Osteopetrosis is a rare genetic disorder characterized by increased bone density due to defective bone resorption of osteoclasts.Approximately,80%of autosomal dominant osteopetrosis type II(ADO-II)patients were usually affected by heterozygous dominant mutations in the chloride voltage-gated channel 7(ClCN7)gene and present early-onset osteoarthritis or recurrent fractures.In this study,we report a case of persistent joint pain without bone injury or underlying history.CASE SUMMARY We report a 53-year-old female with joint pain who was accidentally diagnosed with ADO-II.The clinical diagnosis was based on increased bone density and typical radiographic features.Two heterozygous mutations in the ClCN7 and Tcell immune regulator 1(TCIRG1)genes by whole exome sequencing were identified in the patient and her daughter.The missense mutation(c.857G>A)occurred in the CLCN7 gene p.R286Q,which is highly conserved across species.The TCIRG1 gene point mutation(c.714-20G>A)in intron 7(near the splicing site of exon 7)had no effect on subsequent transcription.CONCLUSION This ADO-II case had a pathogenic CLCN7 mutation and late onset without the usual clinical symptoms.For the diagnosis and assessment of the prognosis for osteopetrosis,genetic analysis is advised.展开更多
BACKGROUND Osteopetrosis is a family of extremely rare diseases caused by failure of osteoclasts and impaired bone resorption. Among them, autosomal dominant osteopetrosis type Ⅱ(ADO Ⅱ), related to the chloride chan...BACKGROUND Osteopetrosis is a family of extremely rare diseases caused by failure of osteoclasts and impaired bone resorption. Among them, autosomal dominant osteopetrosis type Ⅱ(ADO Ⅱ), related to the chloride channel 7(CLCN7) gene, is the most frequent form of osteopetrosis. In this study, we report a de novo mutation of CLCN7 in a patient without the family history of ADO Ⅱ.CASE SUMMARY A 5-year-old Chinese boy with ADO Ⅱ was found to have a de novo mutation in the CLCN7 gene [c.746 C>T(p.P249 L)]. Typical clinical manifestations, including thickening of the cortex of spinal bones and long bones, non-traumatic fracture of the femoral neck, and femoral head necrosis, were found in this patient. The patient is the first reported case of ADO Ⅱ with the missense mutation c.746 C>T(p.P249 L) of the CLCN7 gene reported in China. We also review the available literature on ADO Ⅱ-related CLCN7 mutations, including baseline patient clinical features, special clinical significance, and common mutations.CONCLUSION Our report will enrich the understanding of mutations in ADO Ⅱ patients. The possibility of a de novo mutation should be considered in individuals who have no family history of osteopetrosis.展开更多
Type II autosomal dominant osteopetrosis(ADO2), which is the most common form of osteopetrosis, is caused by heterozygous mutations in the chloride channel 7(CLCN7) gene. The osteopetrosis of ADO2 has been attributed ...Type II autosomal dominant osteopetrosis(ADO2), which is the most common form of osteopetrosis, is caused by heterozygous mutations in the chloride channel 7(CLCN7) gene. The osteopetrosis of ADO2 has been attributed to hypofunctional osteoclasts. The mechanism underlying the abnormality in osteoclast function remains largely unknown. This study was designed to investigate gene mutations and osteoclast function in a case that was clinically diagnosed as ADO2. Genomic DNA was extracted from blood samples of this patient, and the 25 exons of CLCN7 were amplified. Peripheral blood from the ADO2 subject and a healthy age- and sex-matched control was used to evaluate osteoclastogenesis, osteoclast morphology, and bone resorption. Analysis of DNA from the patient showed a germline heterozygous missense mutation,c.1856C>T(p.P619L), in exon 20 of CLCN7. A similar homozygous mutation at this site was previously reported in a patient with autosomal recessive osteopetrosis. When cultured, the peripheral blood mononuclear cells(PBMCs) from the ADO2 patient spontaneously differentiated into mature osteoclasts in vitro. The ADO2 patient’s PBMCs formed enhanced, but heterogeneous, osteoclasts in both the presence and absence of macrophage-colony stimulating factor, and nuclear factor-?B ligand. Bone resorption was reduced in the ADO2 patient’s osteoclasts, which exhibited aberrant morphology and abnormal distribution of integrin avβ3. Gene analysis found increased c-fos expression and reduced Rho A and integrin beta 3expression in ADO2 cells. In conclusion, our data suggest that enhanced, heterogeneous osteoclast induction may be an intrinsic characteristic of ADO2.展开更多
基金Supported by the Science and Technology Plan Program of Sichuan of China,No.2018JY0608。
文摘BACKGROUND Osteopetrosis is a rare genetic disorder characterized by increased bone density due to defective bone resorption of osteoclasts.Approximately,80%of autosomal dominant osteopetrosis type II(ADO-II)patients were usually affected by heterozygous dominant mutations in the chloride voltage-gated channel 7(ClCN7)gene and present early-onset osteoarthritis or recurrent fractures.In this study,we report a case of persistent joint pain without bone injury or underlying history.CASE SUMMARY We report a 53-year-old female with joint pain who was accidentally diagnosed with ADO-II.The clinical diagnosis was based on increased bone density and typical radiographic features.Two heterozygous mutations in the ClCN7 and Tcell immune regulator 1(TCIRG1)genes by whole exome sequencing were identified in the patient and her daughter.The missense mutation(c.857G>A)occurred in the CLCN7 gene p.R286Q,which is highly conserved across species.The TCIRG1 gene point mutation(c.714-20G>A)in intron 7(near the splicing site of exon 7)had no effect on subsequent transcription.CONCLUSION This ADO-II case had a pathogenic CLCN7 mutation and late onset without the usual clinical symptoms.For the diagnosis and assessment of the prognosis for osteopetrosis,genetic analysis is advised.
文摘BACKGROUND Osteopetrosis is a family of extremely rare diseases caused by failure of osteoclasts and impaired bone resorption. Among them, autosomal dominant osteopetrosis type Ⅱ(ADO Ⅱ), related to the chloride channel 7(CLCN7) gene, is the most frequent form of osteopetrosis. In this study, we report a de novo mutation of CLCN7 in a patient without the family history of ADO Ⅱ.CASE SUMMARY A 5-year-old Chinese boy with ADO Ⅱ was found to have a de novo mutation in the CLCN7 gene [c.746 C>T(p.P249 L)]. Typical clinical manifestations, including thickening of the cortex of spinal bones and long bones, non-traumatic fracture of the femoral neck, and femoral head necrosis, were found in this patient. The patient is the first reported case of ADO Ⅱ with the missense mutation c.746 C>T(p.P249 L) of the CLCN7 gene reported in China. We also review the available literature on ADO Ⅱ-related CLCN7 mutations, including baseline patient clinical features, special clinical significance, and common mutations.CONCLUSION Our report will enrich the understanding of mutations in ADO Ⅱ patients. The possibility of a de novo mutation should be considered in individuals who have no family history of osteopetrosis.
基金supported by grants from the National Natural Science Foundation of China(Nos.81572639,81370969 and 81072190 to X Yu)the Ministry of Education of the People's Republic of China(No.20130181110066 to X Yu)the Chengdu Bureau of Science and Technology(No.2014-HM01-00382-SF to X Yu)
文摘Type II autosomal dominant osteopetrosis(ADO2), which is the most common form of osteopetrosis, is caused by heterozygous mutations in the chloride channel 7(CLCN7) gene. The osteopetrosis of ADO2 has been attributed to hypofunctional osteoclasts. The mechanism underlying the abnormality in osteoclast function remains largely unknown. This study was designed to investigate gene mutations and osteoclast function in a case that was clinically diagnosed as ADO2. Genomic DNA was extracted from blood samples of this patient, and the 25 exons of CLCN7 were amplified. Peripheral blood from the ADO2 subject and a healthy age- and sex-matched control was used to evaluate osteoclastogenesis, osteoclast morphology, and bone resorption. Analysis of DNA from the patient showed a germline heterozygous missense mutation,c.1856C>T(p.P619L), in exon 20 of CLCN7. A similar homozygous mutation at this site was previously reported in a patient with autosomal recessive osteopetrosis. When cultured, the peripheral blood mononuclear cells(PBMCs) from the ADO2 patient spontaneously differentiated into mature osteoclasts in vitro. The ADO2 patient’s PBMCs formed enhanced, but heterogeneous, osteoclasts in both the presence and absence of macrophage-colony stimulating factor, and nuclear factor-?B ligand. Bone resorption was reduced in the ADO2 patient’s osteoclasts, which exhibited aberrant morphology and abnormal distribution of integrin avβ3. Gene analysis found increased c-fos expression and reduced Rho A and integrin beta 3expression in ADO2 cells. In conclusion, our data suggest that enhanced, heterogeneous osteoclast induction may be an intrinsic characteristic of ADO2.
