Publications by authors named "Takuo Kubota"

68 Publications

Genotype-phenotype analysis, and assessment of the importance of the zinc-binding site in PHEX in Japanese patients with X-linked hypophosphatemic rickets using 3D structure modeling.

Bone 2021 Jul 29:116135. Epub 2021 Jul 29.

Department of Pediatrics, Osaka University Graduate School of Medicine, Suita, Japan. Electronic address:

X-linked hypophosphatemic rickets (XLH) is an inheritable type of rickets caused by inactivating variants in the phosphate regulating endopeptidase homolog X-linked (PHEX) gene, which results in the overproduction of fibroblast growth factor 23 (FGF23). The mechanism by which PHEX impairment leads to FGF23 overproduction is unknown. Because little is known regarding the genotype-phenotype correlation in Japanese XLH, we summarized the available clinical and genetic data and analyzed the genotype-phenotype relationships using 3-dimensional (3D) structure modeling to clarify the XLH pathophysiology. We retrospectively reviewed the clinical features and performed genetic analysis of 39 Japanese patients with XLH from 28 unrelated pedigrees carrying any known or novel PHEX variant. To predict changes in the 3D structure of mutant PHEX, we constructed a putative 3D model of each mutant and evaluated the effect of structural alteration by genotype-phenotype correlation analysis. Genetic analysis revealed 23 PHEX variants, including eight novel variants. They were associated with high i-FGF23 levels, hypophosphatemia, phosphaturia, high alkaline phosphatase levels, and short stature. No gene dosage effect or genotype-phenotype correlation was observed when truncating and non-truncating variants were compared. However, the conservation of the zinc-binding site and cavity in PHEX had an impact on the elevation of i-FGF23 levels. Via genotype-phenotype relationship analysis using 3D modeling, we showed that the zinc-binding site and cavity in PHEX can play a critical role in its function. These findings provide new genetic clues for investigating the function of PHEX and the pathogenesis of XLH.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1016/j.bone.2021.116135DOI Listing
July 2021

Clinical performance of a novel chemiluminescent enzyme immunoassay for FGF23.

J Bone Miner Metab 2021 Jul 13. Epub 2021 Jul 13.

Fujii Memorial Institute of Medical Sciences, Institute of Advanced Medical Sciences, Tokushima University, 3-18-15, Kuramoto-cho, Tokushima, 770-8503, Japan.

Introduction: Measurement of fibroblast growth factor 23 (FGF23) has been reported to be clinically useful for the differential diagnosis of chronic hypophosphatemia. However, assays for research use only are available in Japan. Thus, the objective of this study was to examine the clinical utility of a novel and automated chemiluminescent enzyme immunoassay for the measurement of FGF23.

Materials And Methods: Participants were recruited from July 2015 to January 2017 at six facilities in Japan. Thirty-eight patients with X-linked hypophosphatemic rickets (XLH 15 males, 23 females, age 0-66 years), five patients with tumour-induced osteomalacia (TIO 3 males, 2 females, age 60-73 years), and twenty-two patients with hypophosphatemia (11 males, 11 females, age 1-75 years) caused due to other factors participated in this study.

Results: With the clinical cut-off value of FGF23 at 30.0 pg/mL indicated in the Diagnostic Guideline of Rickets/Osteomalacia in Japan, the sensitivity and specificity of FGF23-related hypophosphatemic rickets/osteomalacia without vitamin D deficiency (disease group-1) were 100% and 81.8%, respectively, which distinguished it from non-FGF23-related hypophosphatemia (disease group-2). Furthermore, the diagnostic sensitivity of FGF23-related hypophosphatemia with vitamin D deficiency remained at 100%. Among the four patients with FGF23 levels ≥ 30.0 pg/mL in disease group-2, two patients with relatively higher FGF23 values were suspected to have genuine FGF23-related hypophosphatemia, due to the ectopic production of FGF23 in pulmonary and prostate small cell carcinomas.

Conclusion: The novel FGF23 assay tested in this study is useful for the differential diagnosis of hypophosphatemic rickets/osteomalacia in a clinical setting.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1007/s00774-021-01250-1DOI Listing
July 2021

An RNA aptamer restores defective bone growth in FGFR3-related skeletal dysplasia in mice.

Sci Transl Med 2021 05;13(592)

Department of Biology, Faculty of Medicine, Masaryk University, 62500 Brno, Czech Republic.

Achondroplasia is the most prevalent genetic form of dwarfism in humans and is caused by activating mutations in FGFR3 tyrosine kinase. The clinical need for a safe and effective inhibitor of FGFR3 is unmet, leaving achondroplasia currently incurable. Here, we evaluated RBM-007, an RNA aptamer previously developed to neutralize the FGFR3 ligand FGF2, for its activity against FGFR3. In cultured rat chondrocytes or mouse embryonal tibia organ culture, RBM-007 rescued the proliferation arrest, degradation of cartilaginous extracellular matrix, premature senescence, and impaired hypertrophic differentiation induced by FGFR3 signaling. In cartilage xenografts derived from induced pluripotent stem cells from individuals with achondroplasia, RBM-007 rescued impaired chondrocyte differentiation and maturation. When delivered by subcutaneous injection, RBM-007 restored defective skeletal growth in a mouse model of achondroplasia. We thus demonstrate a ligand-trap concept of targeting the cartilage FGFR3 and delineate a potential therapeutic approach for achondroplasia and other FGFR3-related skeletal dysplasias.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1126/scitranslmed.aba4226DOI Listing
May 2021

Alkaline phosphatase in pediatric patients with genu varum caused by vitamin D-deficient rickets.

Endocr J 2021 Jul 24;68(7):807-815. Epub 2021 Mar 24.

Department of Pediatrics, Osaka University Graduate School of Medicine, Osaka, Japan.

An elevated serum alkaline phosphatase (ALP) level is one of the markers for the presence of rickets in children, but it is also associated with bone formation. However, its role in diagnosing genu varum in pediatric patients with vitamin D-deficient rickets is still unknown. To clarify the role of the serum ALP level in assessing the severity of genu varum, we retrospectively investigated this issue statistically using data on rickets such as serum intact parathyroid hormone (iPTH), 25-hydroxyvitamin D, 1,25-dihydroxyvitamin D, ALP, the level of creatinine as the percentage of the median according to age (%Cr), and the metaphyseal diaphyseal angle (MDA) in the lower extremities as an index of the severity of genu varum. A multiple regression analysis revealed that log ALP and %Cr values were negatively associated with MDA values. The former association was also confirmed by a linear mixed model, while iPTH was positively associated with MDA by path model analysis. To elucidate the association of ALP with MDA in the presence of iPTH, we investigated three-dimensional figures by neural network analysis. This indicated the presence of a biphasic association of ALP with MDA: the first phase increases while the second decreases MDA. The latter phenomenon is considered to be associated with the increase in bone formation due to the mechanical stress loaded on the lower extremities. These findings are important and informative for pediatricians to understand the significance of the serum ALP level in pediatric patients with genu varum caused by vitamin D deficiency.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1507/endocrj.EJ20-0622DOI Listing
July 2021

Neonatal cholestasis can be the first symptom of McCune-Albright syndrome: A case report.

World J Clin Pediatr 2021 Mar 9;10(2):7-14. Epub 2021 Mar 9.

Department of Pediatrics, Osaka University Graduate School of Medicine, Osaka 565-0871, Japan.

Background: McCune-Albright syndrome (MAS) is caused by postzygotic somatic mutations of the gene. It is characterized by the clinical triad of fibrous dysplasia, café-au-lait skin spots, and endocrinological dysfunction. Myriad complications in MAS, including hepatobiliary manifestations, are also reported.

Case Summary: This is a case of a 4-year-old boy who presented with MAS with neonatal cholestasis. He was suspected to have Alagille syndrome due to neonatal cholestasis with intrahepatic bile duct paucity in liver biopsy, peripheral pulmonary artery stenosis, and renal tubular dysfunction. By the age of 2 years, his cholestatic liver injury gradually improved, but he had repeated left femoral fractures. He did not exhibit endocrinological abnormality or café-au-lait skin spots. However, MAS was suspected due to fibrous dysplasia at the age of 4 years. No mutation was identified in the gene in the DNA isolated from the peripheral blood, but an activating point mutation (c.601C>T, p.Arg201Cys) was observed in the DNA extracted from the affected bone tissue and that extracted from the formalin-fixed paraffin-embedded liver tissue, which was obtained at the age of 1 mo.

Conclusion: MAS should be considered as a differential diagnosis for transient cholestasis in infancy.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.5409/wjcp.v10.i2.7DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7958557PMC
March 2021

Incidence rate of vitamin D deficiency and FGF23 levels in 12- to 13-year-old adolescents in Japan.

J Bone Miner Metab 2021 May 18;39(3):456-462. Epub 2020 Nov 18.

Department of Pediatrics, Dokkyo Medical University, 880 Kitakobayashi, Mibu, Shimotsuga, Tochigi, 321-0293, Japan.

Introduction: The incidence rate of vitamin D deficiency is increasing throughout the world. We measured the incidence rate of vitamin D deficiency and fibroblast growth factor 23 (FGF23) levels in 12- to 13-year-old adolescents in Japan.

Materials And Methods: A total of 492 adolescents (247 boys and 245 girls) from Japanese community enrolled in this study. 25 hydroxyvitamin D (25(OH)D) was measured with radioimmunoassay. In the subjects with low 25(OH)D levels (≦ 20 ng/ml), intact parathyroid hormone (iPTH), calcium (Ca), phosphorus (P), albumin (Alb), alkaline phosphatase (ALP) and FGF23 were measured.

Results: 25(OH)D levels were significantly lower in girls (20.9 ± 3.1 ng/ml) than in boys (22.2 ± 3.3 ng/ml) (p < 0.0001). Fifty-five boys (22.3%) and 83 (33.9%) girls showed vitamin D deficiency (< 20 ng/ml). One-hundred eighty-six (75.3%) boys and 162 (66.1%) girls showed vitamin D insufficiency (≧ 20 ng/ml, < 30 ng/ml). In the subjects whose 25(OH)D levels were ≦ 20 ng/ml, the levels of iPTH, Ca, P, Alb, ALP and FGF23 were 22.3 ± 9.0 pg/ml, 9.5 ± 0.4 mg/dl, 4.7 ± 0.6 mg/dl, 4.6 ± 0.3 g/dl, 920.8 ± 339.3 U/l and 42.6 ± 26.0 pg/ml, respectively. There was a significant negative association between serum 25(OH)D levels and iPTH [r =  - 0.290 (p < 0.0001)]. There was no significant association between serum 25(OH)D levels and FGF23.

Conclusion: We show that 28% of Japanese 12- to 13-year-old early adolescents suffer from vitamin D deficiency. Findings from this study indicate that vitamin D deficiency requires close oversight in public health during adolescence to ensure proper bone health.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1007/s00774-020-01173-3DOI Listing
May 2021

A case of HDR syndrome coexisting with tetralogy of Fallot, with a novel GATA3 mutation, which manifested as a renal abscess.

CEN Case Rep 2021 05 7;10(2):241-243. Epub 2020 Nov 7.

Department of Pediatrics, Oita University Faculty of Medicine, 1-1 Idaigaoka, Hasama, Yufu, Oita, 879-5593, Japan.

HDR syndrome is characterized by the triad of primary hypoparathyroidism, sensorineural hearing loss and renal malformation with widely variable manifestations. It is an autosomal dominant inherited disease caused by a mutation of the GATA3 (NM_001002295.2), which is located on chromosome 10p14. Congenital heart disease, such as tetralogy of Fallot, a typical complication of DiGeorge syndrome, is a rare complication of HDR syndrome. We herein report a case of HDR syndrome coexisting tetralogy of Fallot with a novel mutation, c.964C > T (p.Gln322*). This case suggested that the screening of renal involvement should be carefully performed in patients with a phenotypic combination of hypoparathyroidism and sensorineural hearing loss, to facilitate the early diagnosis of HDR syndrome. In addition, when the deletion of chromosome 22q11.2 is not detected by a fluorescence in situ hybridization analysis in patients exhibiting the partial phenotype of DiGeorge syndrome, the possibility of HDR syndrome should be considered and the renal function should be repeatedly evaluated.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1007/s13730-020-00551-0DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8019435PMC
May 2021

4-Phenylbutyric acid enhances the mineralization of osteogenesis imperfecta iPSC-derived osteoblasts.

J Biol Chem 2021 Jan-Jun;296:100027. Epub 2020 Nov 23.

Department of Pediatrics, Osaka University Graduate School of Medicine, Suita, Osaka, Japan.

Osteogenesis imperfecta (OI) is a heritable brittle bone disease mainly caused by mutations in the two type I collagen genes. Collagen synthesis is a complex process including trimer formation, glycosylation, secretion, extracellular matrix (ECM) formation, and mineralization. Using OI patient-derived fibroblasts and induced pluripotent stem cells (iPSCs), we investigated the effect of 4-phenylbutyric acid (4-PBA) on collagen synthesis to test its potential as a new treatment for OI. Endoplasmic reticulum (ER) retention of type I collagen was observed by immunofluorescence staining in OI patient-derived fibroblasts with glycine substitution and exon skipping mutations. Liquid chromatography-mass spectrometry analysis revealed excessive glycosylation of secreted type I collagen at the specific sites in OI cells. The misfolding of the type I collagen triple helix in the ECM was demonstrated by the incorporation of heat-dissociated collagen hybridizing peptide in OI cells. Type I collagen was produced excessively by OI fibroblasts with a glycine mutation, but this excessive production was normalized when OI fibroblasts were cultured on control fibroblast-derived ECM. We also found that mineralization was impaired in osteoblasts differentiated from OI iPSCs. In summary, treatment with 4-PBA normalizes the excessive production of type I collagen, reduces ER retention, partially improves misfolding of the type I collagen helix in ECM, and improves osteoblast mineralization. Thus, 4-PBA may improve not only ER retention, but also type I collagen synthesis and mineralization in human cells from OI patients.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1074/jbc.RA120.014709DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7948972PMC
November 2020

Potential pathological role of single nucleotide polymorphism (c.787T>C) in alkaline phosphatase (ALPL) for the phenotypes of hypophosphatasia.

Endocr J 2020 Dec 8;67(12):1227-1232. Epub 2020 Aug 8.

Department of Pediatrics, Osaka University Graduate School of Medicine, Osaka 565-0871, Japan.

Hypophosphatasia (HPP; OMIM 241510, 241500, and 146300) is an inherited metabolic disease characterized by defects of bone and tooth mineralization, which is caused by loss-of-function mutations in the ALPL gene encoding tissue non-specific alkaline phosphatase (TNSALP). In the last three decades, several studies have focused on the genotype-phenotype correlation in hypophosphatasia (HPP). In particular, functional tests based on in vitro analysis for the residual enzymatic activities of mutations have revealed a clear but imperfect genotype-phenotype correlation, suggesting that multiple potential factors modulate the phenotype. One of the missense variants identified in the tissue non-specific alkaline phosphatase (ALPL) gene, c.787T>C, has been considered as a benign polymorphism in HPP; however, its pathogenicity and role in disease manifestation remain controversial. We here report our recent experience of three unrelated families harboring the c.787T>C variant, suggesting clinical implications regarding the controversial pathogenicity of c.787T>C. First, despite the lack of obvious clinical phenotypes, homozygous c.787T>C would decrease the serum level of ALP activity. Second, c.787T>C might deteriorate phenotypes of a patient harboring another ALPL variant, especially one that has thus far presumed to be benign, e.g., the c.1144G>A variant. These cases contribute to the recent advances in understanding HPP to facilitate clinical recognition of more subtle phenotypes, further providing insights into the pathogenesis of HPP.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1507/endocrj.EJ20-0203DOI Listing
December 2020

Long-term outcomes for Asian patients with X-linked hypophosphataemia: rationale and design of the SUNFLOWER longitudinal, observational cohort study.

BMJ Open 2020 06 29;10(6):e036367. Epub 2020 Jun 29.

Department of Pediatrics, Graduate School of Medicine, Osaka University, Suita, Japan.

Introduction: X-linked hypophosphataemic rickets/osteomalacia (XLH) is a chronic, debilitating genetic disease characterised by skeletal abnormalities and growth disorder. The burden of XLH begins in childhood and continues throughout life. Conventional medical therapy with phosphate, active vitamin D and surgery do not address the underlying pathophysiology of the disease. While treatment during childhood may improve bone deformity and growth retardation, a large proportion of adult patients still fail to reach normal stature. Furthermore, adult patients with XLH report comorbidities associated with unresolved childhood disease, as well as newly developed disease-related complications and significantly impaired quality of life (QOL). Despite the multiple negative aspects of XLH, Asian consensus statements for diagnosis and management are lacking.

Methods And Analysis: The Study of longitUdinal observatioN For patients with X-Linked hypOphosphataemic rickets/osteomalacia in collaboration With Asian partnERs study is a longitudinal observational cohort study of patients with XLH, designed to determine the medical characteristics and burdens (physical, emotional and financial) of this progressive disease and to evaluate the impact of treatment (including the use of burosumab) on clinical outcomes. The study was initiated in April 2018, and registration will remain open until 30 April 2022. The sample size planned for analyses is 160 patients, consisting of 100 patients in Japan and 60 patients in Korea. Up to 5 years of observation are planned per patient, from enrolment through to April 2023. Prospective and retrospective data will be collected to evaluate variables, including height/growth, rickets severity score, QOL, motor function and biomarkers for phosphate metabolism and bone turnover.

Ethics And Dissemination: Ethics approval was obtained from the Ethics Committee of Osaka University, the Ethics Committee of Kyowa Kirin Co and by the Ethics Committee of each participating medical institution. Two interim analyses and associated publications are planned using retrospective and enrolment data at year 1 and results at year 3.

Trial Registration Numbers: NCT03745521; UMIN000031605.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1136/bmjopen-2019-036367DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7328740PMC
June 2020

Phenotypes of a family with XLH with a novel mutation.

Hum Genome Var 2020 31;7. Epub 2020 Mar 31.

2Department of Pediatrics, Osaka University Graduate School of Medicine, Osaka, Japan.

X-linked hypophosphatemia (XLH) is the most common form of heritable hypophosphatemic rickets. We encountered a 4-year-old boy with a novel variant in the phosphate-regulating neutral endopeptidase homolog X-linked () gene who presented with a short stature, genu valgum, and scaphocephaly. The same mutation was identified in his mother and sister; however, the patient presented with a more severe case.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1038/s41439-020-0095-1DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7109063PMC
March 2020

Clinical Practice Guidelines for Achondroplasia.

Clin Pediatr Endocrinol 2020 9;29(1):25-42. Epub 2020 Jan 9.

Department of Pediatrics, Osaka University Graduate School of Medicine, Osaka, Japan.

Achondroplasia (ACH) is a skeletal dysplasia that presents with limb shortening, short stature, and characteristic facial configuration. ACH is caused by mutations of the gene, leading to constantly activated FGFR3 and activation of its downstream intracellular signaling pathway. This results in the suppression of chondrocyte differentiation and proliferation, which in turn impairs endochondral ossification and causes short-limb short stature. ACH also causes characteristic clinical symptoms, including foramen magnum narrowing, ventricular enlargement, sleep apnea, upper airway stenosis, otitis media, a narrow thorax, spinal canal stenosis, spinal kyphosis, and deformities of the lower extremities. Although outside Japan, papers on health supervision are available, they are based on reports and questionnaire survey results. Considering the scarcity of high levels of evidence and clinical guidelines for patients with ACH, clinical practical guidelines have been developed to assist both healthcare professionals and patients in making appropriate decisions in specific clinical situations. Eleven clinical questions were established and a systematic literature search was conducted using PubMed/MEDLINE. Evidence-based recommendations were developed, and the guidelines describe the recommendations related to the clinical management of ACH. We anticipate that these clinical practice guidelines for ACH will be useful for healthcare professionals and patients alike.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1297/cpe.29.25DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6958518PMC
January 2020

Clinical Practice Guidelines for Hypophosphatasia.

Clin Pediatr Endocrinol 2020 9;29(1):9-24. Epub 2020 Jan 9.

Department of Pediatrics, Osaka University Graduate School of Medicine, Osaka, Japan.

Hypophosphatasia (HPP) is a rare bone disease caused by inactivating mutations in the gene, which encodes tissue-nonspecific alkaline phosphatase (TNSALP). Patients with HPP have varied clinical manifestations and are classified based on the age of onset and severity. Recently, enzyme replacement therapy using bone-targeted recombinant alkaline phosphatase (ALP) has been developed, leading to improvement in the prognosis of patients with life-threatening HPP. Considering these recent advances, clinical practice guidelines have been generated to provide physicians with guides for standard medical care for HPP and to support their clinical decisions. A task force was convened for this purpose, and twenty-one clinical questions (CQs) were formulated, addressing the issues of clinical manifestations and diagnosis (7 CQs) and those of management and treatment (14 CQs). A systematic literature search was conducted using PubMed/MEDLINE, and evidence-based recommendations were developed. The guidelines have been modified according to the evaluations and suggestions from the Clinical Guideline Committee of The Japanese Society for Pediatric Endocrinology (JSPE) and public comments obtained from the members of the JSPE and a Japanese HPP patient group, and then approved by the Board of Councils of the JSPE. We anticipate that the guidelines will be revised regularly and updated.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1297/cpe.29.9DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6958520PMC
January 2020

Pediatric drug development in Japan: Current issues and perspectives.

Clin Pediatr Endocrinol 2020 9;29(1):1-7. Epub 2020 Jan 9.

Department of Pediatrics, Osaka University Medical Hospital, Osaka, Japan.

The number of clinical trials in Japan that aim to obtain regulatory approval for new drugs and devices has increased for adults, but not children. The following reasons have been proposed for this discrepancy: the wide range of ages from newborns to adolescents, requirements for many drug formulations, the difficulties associated with obtaining consent, and less profit for companies. The processes required to obtain regulatory approval for drugs and devices, particularly in the pediatric field, differ among Japan, Europe, and the United States (US). While clinical trials are not necessarily required for the development of new drugs or obtaining additional indications in Japan, laws in Europe and the US require clinical trials on children for newly developed drugs; however, pharmaceutical companies are entitled to a 6-mo extension for a patent when pediatric data are added to the attached documents for clinical trials. We herein discuss the current status of and issues associated with pediatric drug development, including clinical trials, in Japan as well as future perspectives.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1297/cpe.29.1DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6958521PMC
January 2020

Parental somatogonadal COL2A1 mosaicism contributes to intrafamilial recurrence in a family with type 2 collagenopathy.

Am J Med Genet A 2020 03 19;182(3):454-460. Epub 2019 Dec 19.

Department of Pediatrics, Osaka University Graduate School of Medicine, Osaka, Japan.

The COL2A1 gene encodes the alpha-1 chain of procollagen type 2. Pathogenic variants in the COL2A1 gene are associated with several different types of skeletal dysplasia collectively known as type 2 collagenopathies. Type 2 collagenopathies have an autosomal dominant inheritance. Some germline or somatogonadal mosaicism cases have been reported. We investigated whether somatogonadal mosaicism occurred in a family with two children suspected of type 2 collagenopathies or related diseases. First, we detected a pathogenic variant in the COL2A1 gene in the two affected children by whole exome sequencing (WES). Next, we performed targeted deep sequencing to their parents without the variant by WES. A low level of COL2A1 mosaicism was revealed in the mother's tissues. We concluded that the mother had somatogonadal mosaicism with the COL2A1 mutation arose in the epiblast, and that the intrafamilial recurrence rate of the disease by the somatogonadal mosaicism was higher than by the germline mosaicism. This report suggests that parental low-level mosaicism should be evaluated in those parents with children carrying de novo germline mutations and the targeted deep sequencing is useful to detect them.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1002/ajmg.a.61422DOI Listing
March 2020

Hypophosphatasia in Japan: ALPL Mutation Analysis in 98 Unrelated Patients.

Calcif Tissue Int 2020 03 9;106(3):221-231. Epub 2019 Nov 9.

Department of Pediatrics, Osaka University Graduate School of Medicine, Suita, 565-0871, Osaka, Japan.

Hypophosphatasia (HPP) is highly variable in clinical expression and is generally classified into six subtypes. Although it would be beneficial to be able to predict the clinical course from the ALPL genotype, studies on this issue are limited. Here, we aimed to clarify the features of Japanese HPP and the relationships between genotype and clinical manifestations. We analyzed 98 unrelated Japanese patients to investigate the percentage of each clinical form, frequently detected mutations, and the relationship between the genotype and phenotype. Some of the identified mutants were characterized by transfection experiments. Perinatal severe form was the most frequent (45.9%), followed by perinatal benign form (22.4%). Among the 196 alleles, p.Leu520ArgfsX86 (c.1559delT) was detected in 89 alleles, and p.Phe327Leu (c.979T>C) was identified in 23 alleles. All of the homozygotes for p.Leu520ArgfsX86 were classified into perinatal severe form, and patients carrying p.Phe327Leu in one of the alleles were classified into perinatal benign or odonto HPP. Twenty of the 22 patients with perinatal benign HPP were compound heterozygous for p.Phe327Leu and another mutation. Most patients with odonto HPP were found to be monoallelic heterozygotes for dominant-negative mutations or compound heterozygotes with mutants having residual activity. The high prevalence of p.Leu520ArgfsX86 and p.Phe327Leu mutations might underlie the high rate of perinatal severe and perinatal benign forms, respectively, in Japanese HPP. Although ALPL genotyping would be beneficial for predicting the clinical course to an extent, the observed phenotypical variability among patients sharing the same genotypes suggests the presence of modifiers.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1007/s00223-019-00626-wDOI Listing
March 2020

Japanese nationwide survey of hypophosphatasia reveals prominent differences in genetic and dental findings between odonto and non-odonto types.

PLoS One 2019 10;14(10):e0222931. Epub 2019 Oct 10.

Department of Pediatric Dentistry, Osaka University Graduate School of Dentistry, Osaka, Japan.

Hypophosphatasia (HPP) is a rare and intractable metabolic bone disease caused by mutations in the ALPL gene. Here, we undertook a nationwide survey of HPP in Japan, specifically regarding the prominent genetic and dental manifestations of odonto (n = 16 cases) and other (termed "non-odonto") (n = 36 cases) types. Mean serum alkaline phosphatase (ALP) values in odonto-type patients were significantly greater than those of non-odonto-type patients (P<0.05). Autosomal dominant and autosomal recessive inheritance patterns were detected, respectively, in 89% of odonto-type and 96% of non-odonto-type patients. The ALPL "c.1559delT" mutation, associated with extremely low ALP activity, was found in approximately 70% of cases. Regarding dental manifestations, all patients classified as odonto-type showed early exfoliation of the primary teeth significantly more frequently than patients classified as non-odonto-type (100% vs. 56%; P<0.05). Tooth hypomineralisation was detected in 42% of non-odonto-type patients, but not in any odonto-type patients (0%; P<0.05). Collectively, these results suggest that genetic and dental manifestations of patients with odonto-type and non-odonto-type HPP are significantly different, and these differences should be considered during clinical treatment of patients with HPP.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0222931PLOS
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6786601PMC
March 2020

Impact of fracture characteristics and disease-specific complications on health-related quality of life in osteogenesis imperfecta.

J Bone Miner Metab 2020 Jan 13;38(1):109-116. Epub 2019 Aug 13.

Department of Orthopaedic Surgery, Nagoya University Graduate School of Medicine, 65 Tsurumai, Showa-ku, Nagoya, 466-8550, Japan.

Osteogenesis imperfecta (OI) is a connective tissue disease with bone fragility. Several studies have indicated that physical function in adult OI was correlated to the disease severity, but there have been no reports delineating the impact of the fracture characteristics and disease-specific complications on health-related quality of life (HRQoL). The purpose of this study is to clarify the factors impacted on HRQoL in adult OI patients. We conducted a cross-sectional study between July 2016 and March 2018 and sent a questionnaire regarding HRQoL using Short Form-36 (SF-36) to the OI patients at the age of 20 years or older who had a medical history of the investigators' institutions. The 40 patients completely answered the SF-36. Mental component summary and role/social component summary were unremarkable. Physical component summary (PCS) was significantly associated with z-score for height, teeth abnormality, and cardiopulmonary insufficiency (partial regression coefficient, 3.04, - 9.70, and - 11.35; p, < 0.001, 0.047, and 0.025, respectively). PCS was also significantly lower in the patients who had an initial fracture before the age of 2 years than those without occurrence of fractures until 2 years old (25.80 ± 17.15 versus 44.20 ± 16.54; p = 0.002), or those who had lower extremity fractures more than five times as compared with normal populations. Physical function was decreased in OI patients who had fractures before 2 years old, especially in lower extremity. Appropriate medical managements for cardiopulmonary insufficiency are required not only to maintain physical function but also to decrease mortality.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1007/s00774-019-01033-9DOI Listing
January 2020

Burosumab Improved Histomorphometric Measures of Osteomalacia in Adults with X-Linked Hypophosphatemia: A Phase 3, Single-Arm, International Trial.

J Bone Miner Res 2019 12 1;34(12):2183-2191. Epub 2019 Oct 1.

Division of Pediatric Nephrology, University of California, San Francisco, CA, USA.

In adults with X-linked hypophosphatemia (XLH), excess FGF23 impairs renal phosphate reabsorption and suppresses production of 1,25-dihydroxyvitamin D, resulting in chronic hypophosphatemia and persistent osteomalacia. Osteomalacia is associated with poor bone quality causing atraumatic fractures, pseudofractures, delayed fracture healing, and bone pain. Burosumab is a fully human monoclonal antibody against FGF23. UX023-CL304 is an ongoing, open-label, single-arm, phase 3 study investigating the efficacy of subcutaneous burosumab, 1.0 mg/kg administered every 4 weeks, in improving osteomalacia in adults with XLH who have not been treated for at least 2 years before enrollment. The primary endpoint was improvement in osteoid volume/bone volume assessed by transiliac bone biopsies obtained at baseline and week 48. Additional assessments included serum phosphorus, markers of bone turnover, fracture/pseudofracture healing, and safety. Fourteen subjects enrolled, 13 completed 48 weeks, and 11 completed paired biopsies. All osteomalacia-related histomorphometric measures improved significantly at week 48 (mean percent change: osteoid volume/bone volume, -54%, osteoid thickness, -32%, osteoid surface/bone surface, -26%, [median] mineralization lag time, -83%). Mean serum phosphorus concentration averaged across the mid-point of the dose cycle between weeks 0 and 24 was 3.3 mg/dL, a 50% increase from 2.2 mg/dL at baseline. Markers of bone formation and resorption increased at week 48 (least squares [LS] mean increase: P1NP, +77%; CTx, +36%; both p < 0.0001). All subjects had one or more treatment-emergent adverse event (AE). Most AEs were mild to moderate in severity. Two subjects experienced serious AEs (migraine; paresthesia) that were unrelated to treatment and resolved. Eleven subjects had 18 biopsy procedure-related AEs: 14 for pain, two for itch, and one each for headache and bandage irritation. No deaths or incidents of hyperphosphatemia occurred. In conclusion, by normalizing phosphate homeostasis, burosumab significantly improved osteomalacia in adults with XLH, which likely explains the improved fracture healing and amelioration of skeletal complications. © 2019 The Authors. Journal of Bone and Mineral Research published by American Society for Bone and Mineral Research.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1002/jbmr.3843DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6916280PMC
December 2019

Genetic correction of induced pluripotent stem cells mediated by transcription activator-like effector nucleases targeting ALPL recovers enzyme activity and calcification in vitro.

Mol Genet Metab 2019 06 28;127(2):158-165. Epub 2019 May 28.

Department of Pediatrics, Osaka University Graduate School of Medicine, Osaka, Japan. Electronic address:

Hypophosphatasia (HPP) is an inheritable disease affecting both skeletal systems and extra-skeletal organs due to mutations of the gene ALPL, which encodes tissue-nonspecific alkaline phosphatase. Recently, an enzyme replacement therapy using asfotase alfa was developed to ameliorate the complications of HPP. However, it requires frequent injections and is expensive to maintain. As an alternative, cell and gene therapy using human induced pluripotent stem cells (iPSCs) after precise correction of the mutation is feasible due to advances in genome-editing technology. In the study, we examined the alkaline phosphatase (ALP) activity and calcification in vitro of two childhood HPP patient-derived iPSCs after the correction of the c.1559delT mutation, which is the most frequent mutation in Japanese patients with HPP, using transcription activator-like effector nucleases (TALENs). The gene correction targeting vector was designed for site-directed mutagenesis using TALEN. After selection with antibiotics, some clones with the selection cassette were obtained. Gene correction was confirmed by Sanger sequencing. The mutation was corrected in one allele of ALPL in homozygous patients and compound heterozygous patients. The correction of ALPL did not result in an increase in ALP when the selection cassette remained. Conversely, iPSCs exhibited ALP activity after the elimination of the cassette using Cre/LoxP. The quantitative analysis showed the half ALP activity in corrected iPSCs of that of control iPSCs, corresponding to heterozygous correction of the mutation. In addition, osteoblasts differentiated from the corrected iPSCs exhibited high ALP activity and some calcification in vitro. Moreover, the osteoblast-like phenotype was confirmed by increased expression of osteoblast-specific genes such as COL1A1 and osteocalcin. These results suggest that gene correction in iPSCs may be a candidate treatment for HPP patients.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1016/j.ymgme.2019.05.014DOI Listing
June 2019

Continued Beneficial Effects of Burosumab in Adults with X-Linked Hypophosphatemia: Results from a 24-Week Treatment Continuation Period After a 24-Week Double-Blind Placebo-Controlled Period.

Calcif Tissue Int 2019 Sep 4;105(3):271-284. Epub 2019 Jun 4.

Yale University School of Medicine, New Haven, CT, USA.

Burosumab, a fully human monoclonal antibody to FGF23, is the only approved treatment for X-linked hypophosphatemia (XLH), a rare genetic disorder characterized by renal phosphate wasting and substantial cumulative musculoskeletal morbidity. During an initial 24-week randomized, controlled trial, 134 adults with XLH received burosumab 1 mg/kg (n = 68) or placebo (n = 66) every 4 weeks. After 24 weeks, all subjects received open-label burosumab until week 48. This report describes the efficacy and safety of burosumab during the open-label treatment period. From weeks 24-48, serum phosphorus concentrations remained normal in 83.8% of participants who received burosumab throughout and were normalized in 89.4% who received burosumab after placebo. By week 48, 63.1% of baseline fractures/pseudofractures healed fully with burosumab, compared with 35.2% with burosumab after placebo. In both groups, burosumab was associated with clinically significant and sustained improvement from baseline to week 48 in scores for patient-reported outcomes of stiffness, pain, physical function, and total distance walked in 6 min. Rates of adverse events were similar for burosumab and placebo. There were no fatal adverse events or treatment-related serious adverse events. Nephrocalcinosis scores did not change from baseline by more than one grade at either week 24 or 48. These data demonstrate that in participants with XLH, continued treatment with burosumab is well tolerated and leads to sustained correction of serum phosphorus levels, continued healing of fractures and pseudofractures, and sustained improvement in key musculoskeletal impairments.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1007/s00223-019-00568-3DOI Listing
September 2019

Adult hypophosphatasia with compound heterozygous p.Phe327Leu missense and c.1559delT frameshift mutations in tissue-nonspecific alkaline phosphatase gene: a case report.

J Med Case Rep 2019 Apr 24;13(1):101. Epub 2019 Apr 24.

Department of General Medicine, Gunma University Graduate School of Medicine, 3-39-15 Showa-machi, Maebashi, Gunma, 371-8511, Japan.

Background: Hypophosphatasia is an inherited bone disease characterized by low alkaline phosphatase activity encoded by ALPL. Clinically, hypophosphatasia can be categorized as perinatal, infantile, childhood, and adult forms, as well as odonto-hypophosphatasia, according to the age at first sign or dental manifestations. Adult hypophosphatasia typically presents in middle-aged patients who appear to be in good health in early adulthood and manifests as painful feet caused by recurrent, slow-healing stress fractures of the lower limb. Because the symptoms of adult hypophosphatasia vary and are common, many patients with hypophosphatasia might be not diagnosed accurately and thus may receive inappropriate treatment.

Case Presentation: We report a case of a 35-year-old Japanese woman with low serum alkaline phosphatase detected at a routine medical checkup. She had mild muscle/bone pain but no history of rickets, fractures, or dental problems. Measurement of bone mineral density of the lumbar spine and the femoral neck revealed osteopenia below the expected range for age in a young adult. Abdominal ultrasonography revealed numerous microcalcifications in both kidneys. Analysis of amino acids in urine revealed that phosphoethanolamine was elevated. Low serum alkaline phosphatase activity, elevation of phosphoethanolamine, and low bone mineral density supported the diagnosis of hypophosphatasia. ALPL mutation analysis revealed two mutations: p.Phe327Leu and c.1559delT. These genetic abnormalities were previously reported in perinatal, infantile, and childhood but not adult hypophosphatasia. On the basis of the clinical presentation, laboratory and imaging findings, and genetic analyses, the patient was definitively diagnosed with adult hypophosphatasia. To the best of our knowledge, this is the first case report of adult hypophosphatasia with the compound heterozygous mutations p.Phe327Leu and c.1559delT.

Conclusions: Although the risk of bone fracture was high in this case, treatment approaches differ between osteoporosis and hypophosphatasia. Because adult hypophosphatasia diagnosis is often difficult because of their varied symptoms, hypophosphatasia should be considered in the differential diagnosis of low serum alkaline phosphatase. Early diagnosis is important so that appropriate treatment can be initiated.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1186/s13256-019-2045-4DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6480864PMC
April 2019

A novel mutation in basal cell nevus syndrome with rare craniofacial features.

Hum Genome Var 2019 2;6:16. Epub 2019 Apr 2.

1Department of Orthodontics and Dentofacial Orthopedics, Osaka University Graduate School of Dentistry, Suita, Japan.

Basal cell nevus syndrome (BCNS) is a rare, multisystem, autosomal dominant disorder that is characterized by various phenotypes, including multiple basal cell carcinomas of the skin, odontogenic keratocysts of the jaws, and occasionally cleft lip and/or palate. In this report, we describe a 6-year-old Japanese girl with a novel heterozygous nonsense mutation in who exhibited rare craniofacial phenotypes, such as oligodontia and a short-tooth root.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1038/s41439-019-0047-9DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6445144PMC
April 2019

Metreleptin treatment for congenital generalized lipodystrophy type 4 (CGL4): a case report.

Clin Pediatr Endocrinol 2019 31;28(1):1-7. Epub 2019 Jan 31.

Department of Pediatrics, Osaka University Graduate School of Medicine, Osaka, Japan.

Congenital generalized lipodystrophy type 4 (CGL4) is a rare disease caused by mutations in the gene polymerase I and transcript release factor (), the main symptoms of which are systemic reductions in adipose tissue and muscular dystrophy. The strategy of treating CGL4 is to improve the insulin resistance and hypertriglyceridemia that result from systemic reductions in adipose tissue. Metreleptin, a synthetic analog of human leptin, is effective against generalized lipodystrophies; however, there are no reports of the use of metreleptin in the treatment of CGL4. Herein, we discuss the treatment of a six-year-old boy diagnosed with CGL4 due to a homozygous mutation in with metreleptin. His serum triglyceride level and homeostasis model assessment of insulin resistance (HOMA-IR) value decreased after two months of metreleptin treatment. However, the efficacy of metreleptin gradually decreased, and the treatment was suspended because anaphylaxis occurred after the dosage administered was increased. Subsequently, his serum triglyceride level and HOMA-IR value significantly increased. Anti-metreleptin-neutralizing antibodies were detected in his serum, which suggested that these antibodies reduced the efficacy of metreleptin and caused increased hypersensitivity. Thus, metreleptin appeared to be efficacious in the treatment of CGL4 in the short term, although an adverse immune response resulted in treatment suspension. Further studies are needed to evaluate metreleptin treatments for CGL4.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1297/cpe.28.1DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6356095PMC
January 2019

Physical, Mental, and Social Problems of Adolescent and Adult Patients with Achondroplasia.

Calcif Tissue Int 2019 04 1;104(4):364-372. Epub 2019 Feb 1.

Department of Orthopaedic Surgery, Nagoya University Graduate School of Medicine, 65 Tsurumai, Showa-ku, Nagoya, 466-8550, Japan.

Patients with achondroplasia (ACH) require various medical interventions throughout the lifetime. Survey of health-related quality of life (HRQoL) in adult ACH patients is essential for the evaluation of treatment outcomes performed during childhood such as growth hormone administration and limb lengthening surgeries, but no study focused on the treatment strategy by analyzing HRQoL of ACH patients. The purpose of this study was to assess whether final height impacted on HRQoL and to evaluate what kinds of medical interventions were positively or negatively associated with HRQoL. We included 184 ACH patients (10-67 years old) who were registered in the patients' associations or who had a medical history of the investigators' institutions, and analyzed HRQoL by using Short Form-36 and patient demographics. Physical component summary (PCS) was significantly lower than the standard values in each age, especially in elderly populations, while mental component summary (MCS) was similar to the standard values. Role/social component summary was deteriorated only in elderly populations. The PCS was improved in the patients who had a height of 140 cm or taller (p < 0.001). The PCS and MCS were strongly associated with the past medical history of spine surgeries (p < 0.001 and p = 0.028, respectively). A treatment strategy would be planned to gain a final height of 140 cm or taller during childhood in combination with growth hormone administration and limb lengthening surgeries. Appropriate medical management for neurological complications of adult ACH patients is required to maintain physical and mental function.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1007/s00223-019-00518-zDOI Listing
April 2019

CREB activation in hypertrophic chondrocytes is involved in the skeletal overgrowth in epiphyseal chondrodysplasia Miura type caused by activating mutations of natriuretic peptide receptor B.

Hum Mol Genet 2019 04;28(7):1183-1198

Department of Bone and Mineral Research, Research Institute, Osaka Women's and Children's Hospital, Osaka Prefectural Hospital Organization, Izumi, Osaka, Japan.

Natriuretic peptide receptor B (NPRB) produces cyclic guanosine monophosphate (cGMP) when bound by C-type natriuretic peptide (CNP). Activating mutations in NPRB cause a skeletal overgrowth disorder, which has been named epiphyseal chondrodysplasia, Miura type (ECDM; OMIM #615923). Here we explored the cellular and molecular mechanisms for the skeletal overgrowth in ECDM using a mouse model in which an activating mutant NPRB is specifically expressed in chondrocytes. The mutant mice (NPRB[p.V883M]-Tg) exhibited postnatal skeletal overgrowth and increased cGMP in cartilage. Both endogenous and transgene-derived NPRB proteins were localized at the plasma membrane of hypertrophic chondrocytes. The hypertrophic zone of growth plate was thickened in NPRB[p.V883M]-Tg. An in vivo BrdU-labeling assay suggested that some of the hypertrophic chondrocytes in NPRB[p.V883M]-Tg mice continued to proliferate, although wild-type (WT) chondrocytes stopped proliferating after they became hypertrophic. In vitro cell studies revealed that NPRB activation increased the phosphorylation of cyclic AMP-responsive element binding protein (CREB) and expression of cyclin D1 in matured chondrocytes. Treatment with cell-permeable cGMP also enhanced the CREB phosphorylation. Inhibition of cyclic adenosine monophosphate (cAMP)/protein kinase A pathway had no effects on the CREB phosphorylation induced by NPRB activation. In immunostaining of the growth plates for the proliferation marker Ki67, phosphorylated CREB and cyclin D1, most signals were similarly observed in the proliferating zone in both genotypes, but some cells in the hypertrophic zone of NPRB[p.V883M]-Tg were also positively stained. These results suggest that NPRB activation evokes its signal in hypertrophic chondrocytes to induce CREB phosphorylation and make them continue to proliferate, leading to the skeletal overgrowth in ECDM.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1093/hmg/ddy428DOI Listing
April 2019

Japanese patient with Cole-carpenter syndrome with compound heterozygous variants of SEC24D.

Am J Med Genet A 2018 12 21;176(12):2882-2886. Epub 2018 Nov 21.

Department of Pediatrics, Osaka University Graduate School of Medicine, Osaka, Japan.

Cole-Carpenter syndrome is a rare skeletal dysplasia associated with low-bone mass or an osteogenesis imperfecta (OI)-like syndrome. Only 3 and 6 variants in SEC24D have been reported in patients with Cole-Carpenter syndrome type 2 and autosomal recessive OI, respectively. We describe a 15-year-old Japanese boy with short stature of the short-trunk type and craniofacial abnormalities including ocular proptosis, marked frontal bossing, midface hypoplasia, and micrognathia. These features were consistent with a diagnosis of Cole-Carpenter syndrome. He had low-bone mineral density and basilar impression. Whole exome sequencing analysis identified biallelic variants in SEC24D (p.Arg484* and p.Arg313His) in the patient. We will report a patient with compound heterozygous variants of SEC24D causing Cole-Carpenter syndrome type 2.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1002/ajmg.a.40643DOI Listing
December 2018

Functional analysis of monocarboxylate transporter 8 mutations in Japanese Allan-Herndon-Dudley syndrome patients.

Endocr J 2019 Jan 25;66(1):19-29. Epub 2018 Oct 25.

Department of Pediatrics, Graduate School of Medicine, Osaka University, Suita, Japan.

Monocarboxylate transporter 8 (MCT8) facilitates T3 uptake into cells. Mutations in MCT8 lead to Allan-Herndon-Dudley syndrome (AHDS), which is characterized by severe psychomotor retardation and abnormal thyroid hormone profile. Nine uncharacterized MCT8 mutations in Japanese patients with severe neurocognitive impairment and elevated serum T3 levels were studied regarding the transport of T3. Human MCT8 (hMCT8) function was studied in wild-type (WT) or mutant hMCT8-transfected human placental choriocarcinoma cells (JEG3) by visualizing the locations of the proteins in the cells, detecting specific proteins, and measuring T3 uptake. We identified 6 missense (p.Arg445Ser, p.Asp498Asn, p.Gly276Arg, p.Gly196Glu, p.Gly401Arg, and p.Gly312Arg), 2 frameshift (p.Arg355Profs*64 and p.Tyr550Serfs*17), and 1 deletion (p.Pro561del) mutation(s) in the hMCT8 gene. All patients exhibited clinical characteristics of AHDS with high free T3, low-normal free T4, and normal-elevated TSH levels. All tested mutants were expressed at the protein level, except p.Arg355Profs*64 and p.Tyr550Serfs*17, which were truncated, and were inactive in T3 uptake, excluding p.Arg445Ser and p.Pro561del mutants, compared with WT-hMCT8. Immunocytochemistry revealed plasma membrane localization of p.Arg445Ser and p.Pro561del mutants similar with WT-hMCT8. The other mutants failed to localize in significant amount(s) in the plasma membrane and instead localized in the cytoplasm. These data indicate that p.Arg445Ser and p.Pro561del mutants preserve residual function, whereas p.Asp498Asn, p.Gly276Arg, p.Gly196Glu, p.Gly401Arg, p.Gly312Arg, p.Arg355Profs*64, and p.Tyr550Serfs*17 mutants lack function. These findings suggest that the mutations in MCT8 cause loss of function by reducing protein expression, impairing trafficking of protein to plasma membrane, and disrupting substrate channel.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1507/endocrj.EJ18-0251DOI Listing
January 2019

[Rickets/Osteomalacia. Symptomatic vitamin D deficiency in children and its prevention and treatment.]

Authors:
Takuo Kubota

Clin Calcium 2018;28(10):1381-1386

Department of Pediatrics, Osaka University Graduate School of Medicine, Japan.

Vitamin D deficiency rickets is characterized by mineralization impairment in bone and cartilage of children caused by vitamin D deficiency in the body due to limited sunlight exposure and vitamin D intake. Vitamin D supplementation is recommended in developed countries. Low calcium intake is a risk factor for vitamin D deficiency rickets. For treatment, native vitamin D is used in developed countries, while active vitamin D is used in Japan.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/CliCa181013811386DOI Listing
June 2019

Development of scoliosis in young children with osteogenesis imperfecta undergoing intravenous bisphosphonate therapy.

J Bone Miner Metab 2019 May 5;37(3):545-553. Epub 2018 Sep 5.

Department of Orthopedic Surgery, Faculty of Medicine, Graduate School of Medicine, Osaka University, 2-2 Yamadaoka, Suita, Osaka, 565-0871, Japan.

The purpose of this study was to clarify the prevalence of scoliosis and determine risk factors for the development of scoliosis in young children with osteogenesis imperfecta (OI) who underwent intravenous pamidronate (PAM) therapy. Thirty-four young children with OI who had no scoliosis at the first PAM administration underwent cyclic PAM therapy alone. The medical records and radiographs of these patients were retrospectively reviewed. We examined the relationship between scoliosis (Cobb angle ≥ 10) and type of OI (Sillence classification: types I, III, and IV), physical mobility, Z-scores of bone mineral density in L2-4 of the lumbar spine (L2-4 BMD Z-scores), age of patients at first treatment with PAM, pelvic frontal tilt and leg-length discrepancy. The prevalence of scoliosis was 23.5% in 34 young children with OI who underwent PAM therapy for a mean of 4.2 years. Lower L2-4 BMD Z-scores, the presence of coronal and sagittal vertebral deformities and higher percentage of corrective osteotomy in the lower extremities were significant risk factors for the development of scoliosis. In patients with type III or IV OI, L2-4 BMD Z-scores were significantly lower (p = 0.02) and the percentage of patients who started PAM therapy in early childhood was significantly lower in scoliosis group than in the non-scoliosis group (p = 0.01). Development of scoliosis depends on the severity of OI and has a strong relationship with bone fragility even under PAM therapy. Starting intravenous PAM therapy in infancy or early childhood has a potential to prevent the occurrence and progression of scoliosis associated with bone fragility in young children with severe type III or IV OI.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1007/s00774-018-0952-xDOI Listing
May 2019
-->