Publications (49)146.84 Total impact
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Article: Current status of hepatic glycogen storage disease in Japan: clinical manifestations, treatments and long-term outcomes.
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ABSTRACT: Many reports have been published on the long-term outcome and treatment of hepatic glycogen storage diseases (GSDs) overseas; however, none have been published from Japan. We investigated the clinical manifestations, treatment, and prognosis of 127 hepatic GSD patients who were evaluated and treated between January 1999 and December 2009. A characteristic genetic pattern was noted in the Japanese GSD patients: most GSD Ia patients had the g727t mutation, and many GSD Ib patients had the W118R mutation. Forty-one percent (14/34) of GSD Ia patients and 18% (2/11) of GSD Ib patients of ages 13 years 4 months had liver adenoma. Among subjects aged 10 years, 19% (7/36) of the GSD Ia patients and none of the GSD Ib patients had renal dysfunction. The mean height of male GSD Ia patients aged 18 years was 160.8±10.6 cm (n=14), and that of their female counterparts was 147.8±3.80 cm (n=9). Patients with hepatic GSDs develop a variety of symptoms but can survive in the long term by diet therapy, corn starch treatment and supportive care. Liver transplantation for hepatic GSDs is an important treatment strategy and can help improve the patients'quality of life.Journal of Human Genetics advance online publication, 14 March 2013; doi:10.1038/jhg.2013.17.Journal of Human Genetics 03/2013; · 2.57 Impact Factor -
Article: Molecular and clinical studies in 138 Japanese patients with silver-russell syndrome.
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ABSTRACT: BACKGROUND: Recent studies have revealed relative frequency and characteristic phenotype of two major causative factors for Silver-Russell syndrome (SRS), i.e. epimutation of the H19-differentially methylated region (DMR) and uniparental maternal disomy 7 (upd(7)mat), as well as multilocus methylation abnormalities and positive correlation between methylation index and body and placental sizes in H19-DMR epimutation. Furthermore, rare genomic alterations have been found in a few of patients with idiopathic SRS. Here, we performed molecular and clinical findings in 138 Japanese SRS patients, and examined these matters. METHODOLOGYPRINCIPAL FINDINGS: We identified H19-DMR epimutation in cases 1-43 (group 1), upd(7)mat in cases 44-52 (group 2), and neither H19-DMR epimutation nor upd(7)mat in cases 53-138 (group 3). Multilocus analysis revealed hyper- or hypomethylated DMRs in 2.4% of examined DMRs in group 1; in particular, an extremely hypomethylated ARHI-DMR was identified in case 13. Oligonucleotide array comparative genomic hybridization identified a ∼3.86 Mb deletion at chromosome 17q24 in case 73. Epigenotype-phenotype analysis revealed that group 1 had more reduced birth length and weight, more preserved birth occipitofrontal circumference (OFC), more frequent body asymmetry and brachydactyly, and less frequent speech delay than group 2. The degree of placental hypoplasia was similar between the two groups. In group 1, the methylation index for the H19-DMR was positively correlated with birth length and weight, present height and weight, and placental weight, but with neither birth nor present OFC. CONCLUSIONSSIGNIFICANCE: The results are grossly consistent with the previously reported data, although the frequency of epimutations is lower in the Japanese SRS patients than in the Western European SRS patients. Furthermore, the results provide useful information regarding placental hypoplasia in SRS, clinical phenotypes of the hypomethylated ARHI-DMR, and underlying causative factors for idiopathic SRS.PLoS ONE 01/2013; 8(3):e60105. · 4.09 Impact Factor -
Article: Improved neurologic prognosis for a patient with propionic acidemia who received early living donor liver transplantation.
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ABSTRACT: Despite medical therapy, patients with propionic academia (PA) still display a tendency to develop epilepsy. Patients with neonatal-onset PA who have received early living donor liver transplantation (LDLT) are limited in number, and the effect on neurologic prognosis, including epilepsy, is not clear. We report a patient with PA whose EEG findings improved dramatically after undergoing LDLT at age 7months. The patient's neurologic development and brain MRI findings were quite satisfactory at age 2years and 3months. LDLT is effective not only in preventing metabolic decompensation, but also in improving neurologic function to ensure better quality of life.Molecular Genetics and Metabolism 10/2012; · 3.19 Impact Factor -
Article: Usefulness of insulin detemir in Japanese children with type 1 diabetes.
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ABSTRACT: Background: This multicenter observational study was conducted to investigate the efficacy and safety of insulin detemir (detemir) for diabetes management in Japanese children and adolescents. Methods: Data from the Japanese Study Group of Insulin Therapy for Childhood and Adolescent Diabetes database were analyzed. Ninety children (32 boys, 58 girls; mean age, 11.9 ± 3.8 years) who transferred from a neutral protamine Hagedorn insulin or insulin glargine basal-bolus regimen to detemir basal-bolus therapy and who were observed for at least 12 months were identified. Clinical data obtained at 0, 3, 6, and 12 months were analyzed to determine the type of bolus insulin used, number and timing of detemir injections, detemir dose as a proportion of the total insulin dose, hemoglobin A1c (HbA1c), fasting blood glucose (FBG) and frequency of severe hypoglycemia. Results: Twelve months after switching to detemir, the detemir dose represented 39.8% of the total insulin dose, and 37.8% of patients were being treated with twice-daily injections. HbA1c and FBG were significantly reduced from baseline at 3 and 6 months but not at 12 months. Considering the seasonal HbA1c variation in the Japanese population, a separate analysis was performed using data for 65 children (21 boys, 44 girls; mean age, 11.6 ± 2.9 years) who switched to detemir during the winter. Subset analysis showed significant HbA1c reductions from baseline at all specified times. The incidence of severe hypoglycemia during detemir treatment was 4.4 episodes per 100 patient-years. Conclusions: Detemir is an effective and safe basal insulin for diabetes management in Japanese children and adolescents.Pediatrics International 06/2012; · 0.63 Impact Factor -
Article: Standardized centile curves and reference intervals of serum insulin-like growth factor-I (IGF-I) levels in a normal Japanese population using the LMS method.
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ABSTRACT: Measurements of insulin-like growth factor-I (IGF-I) are useful not only for diagnosis and management of patients with growth hormone (GH)-related disorders but also for assessing nutritional status. We reported population-based references of serum IGF-I in 1996. However, they did not properly reflect data in the transition period from puberty to maturity. The aim of the present study was to re-establish a set of normative data for IGF-I for the Japanese population. The study included 1,685 healthy Japanese subjects (845 males, 840 females) from 0 to 83 years old. Subjects suffering from diseases that could affect IGF-I levels were excluded. Obese or extremely thin adult subjects were also excluded. IGF-I concentrations were determined by commercially available immunoradiometric assays. The reference intervals were calculated using the LMS method. Median IGF-I levels reached 310 ng/mL in males at the age of 14 years and 349 ng/mL in females at the age of 13 years, falling to 124 ng/mL and 103 ng/mL, respectively, by the age of 70 years. The mean pretreatment IGF-1 SD scores in patients with severe GH deficiency (GHD) obtained from the database of the Foundation for Growth Science and from clinical studies for adult GHD were -2.1±1.6 and -4.9±2.5, respectively. The present study established age- and gender-specific normative IGF-I data for the Japanese population and showed the utility of these references for screening patients with severe GHD.Endocrine Journal 05/2012; 59(9):771-80. · 2.03 Impact Factor -
Article: Glycemic management in living donor liver transplantation for patients with glycogen storage disease type 1b.
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ABSTRACT: GSD type 1b is an autosomal recessive inborn error of carbohydrate metabolism caused by defects of the G6Pase translocase (G6PT). Patients with GSD1b have severe hypoglycemia with several clinical manifestations of hepatomegaly, obesity, a doll-like face, and neutropenia. LT has been indicated for severe glucose intolerance. This study retrospectively reviewed glycemic management of eight children with a diagnosis of GSD1b who underwent liver transplantation (LDLT). Between November 2005 and September 2011, 172 children underwent LDLT, of which eight (4.7%) were indicated for GSD1b. Glucose-rich solution was placed in all children when preoperative fasting started to prevent preoperative hypoglycemia. During the reperfusion of graft, the glucose administration could significantly be reduced to maintain the proper blood glucose level, while the dosage of glucose administration prior to reperfusion of graft was significantly higher in the patients with GSD1b in comparison with patients with BA. The current series also showed significantly high incidence of infectious complications in the patients with GSD1b owing to persistent neutropenia after LDLT. All patients are doing well with an excellent quality of life owing to the stabilization of glucose intolerance. This current study clearly documented drastic change in glycemic management in LDLT. Cautious perioperative management to prevent hypoglycemia and infection is crucial for successful LT.Pediatric Transplantation 05/2012; 16(5):465-70. · 1.48 Impact Factor -
Article: Long-term outcome and intervention of urea cycle disorders in Japan.
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ABSTRACT: Urea cycle disorders (UCDs) are one of the most frequently inherited metabolic diseases in Japan, with an estimated prevalence of 1 per 50,000 live births. Here, we investigated the clinical manifestations, treatment, and prognosis of 177 patients with UCDs who were evaluated and treated from January 1999 to March 2009. These included 77 cases of neonatal-onset UCDs and 91 cases of late-onset UCDs. The most common UCD was ornithine transcarbamylase deficiency (OTCD), which accounted for 116 out of 177 patients. This result is similar to a previous study performed between 1978 and 1995 in Japan: OTCD accounted for about two-thirds of the total number of UCD cases. We studied the relationship between prognosis and the peak blood ammonia level at the onset in 151 UCD patients. Compared with a previous survey conducted in Japan, we found that a greater number of patients survived without any mental retardation despite their peak blood ammonia levels being greater than 360 μmol/l. The 5-year survival rate of patients with OTCD improved to 86% for those with the neonatal-onset type and to 92% for those with the late-onset type. We hypothesize that the increased survival rate is due to early diagnosis and better treatments that are now available in Japan. It is very important to diagnose and treat UCDs, especially OTCD, when the blood ammonia levels in patients are low. The outcome in patients with low blood ammonia levels was better than that in patients with high blood ammonia levels.Journal of Inherited Metabolic Disease 12/2011; 35(5):777-85. · 3.58 Impact Factor -
Article: Living-donor liver transplantation for propionic acidemia.
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ABSTRACT: Propionic acidemia is a rare autosomal recessive disorder affecting the catabolism of branched-chain amino acids because of a genetic defect in PCC. Despite the improvements in medical treatment with protein restriction, sufficient caloric intake, supplementation of l-carnitine, and metronidazole, patients with the severe form of propionic acidemia have life-threatening metabolic acidosis, hyperammonemia, and cardiomyopathy, which results in serious neurologic sequelae and sometimes death. This study retrospectively reviewed three children with neonatal-onset propionic acidemia who received LDLT. Between November 2005 and December 2010, 148 children underwent LDLT, with an overall patient survival of 90.5%, in our center. Three patients were indicated for transplantation because of propionic acidemia. All recipients achieved a resolution of metabolic derangement and better quality of life with protein restriction and medication, although urine methylcitrate and serum propionylcarnitine levels did not decrease markedly. LT can reduce the magnitude of progressive cardiac/neurologic disability as a result of poor metabolic control. Further evaluation is therefore required to determine the long-term suitability of this treatment modality.Pediatric Transplantation 12/2011; 16(3):230-4. · 1.48 Impact Factor -
Article: HLA-class II and class I genotypes among Japanese children with Type 1A diabetes and their families.
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ABSTRACT: To determine the HLA-DRB1, DQB1, DPB1, A, C, and B genotypes among Japanese children with autoimmune type 1 diabetes. Four hundred and thirty patients who were GADAb and/or IA-2Ab-positive (Type 1A) were recruited from 37 medical centers as part of a nationwide multicenter collaborative study. DNA samples from 83 siblings of the children with Type 1A diabetes and 149 parent-child trios were also analyzed. A case-control study and a transmission disequilibrium test (TDT) were then performed. The susceptible and protective DRB1 and DQB1 alleles and haplotypes were confirmed. DPB1 alleles unique to the Japanese population and those common to multiple ethnic groups were also present. A linkage disequilibrium (LD) analysis showed both susceptible and protective haplotypes. The TDT did not reveal any alleles that were transmitted preferentially from the mother or father to children with Type 1A. Homozygosity for DRB1-09:01-DQB1-03:03 and heterozygosity for DRB1-04:05-DQB1-04:01 and DRB1-08:02-DQB1-03:02 were associated with an extremely high risk of Type 1A. A comparison of children with Type 1A and their parents and siblings suggested a dose effect of susceptible DRB1-DQB1 haplotypes and an effect of protective alleles on immunological pathogenesis. DRB1-09:01 appeared to be strongly associated with an early onset in preschool children with Type 1A diabetes. This study demonstrated the characteristic association of HLA-class II and class I genes with Type 1A diabetes among Japanese children. A TDT did not reveal the genomic imprinting of HLA-class II and class I genes in Type 1A diabetes.Pediatric Diabetes 11/2011; 13(1):33-44. · 2.16 Impact Factor -
Article: Preoperative dialysis for liver transplantation in methylmalonic acidemia.
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ABSTRACT: Dialysis immediately before liver transplantation for patients with methylmalonic academia (MMA) with the mut0 mutation is considered to be necessary to reduce plasma methylmalonic acid (MMA) levels and prevent metabolic decompensation for a successful surgical outcome; however, this has not yet been conclusively confirmed. Ten pediatric patients underwent living donor liver transplantation at the National Center for Child Health and Development, Tokyo, Japan. Seven patients received dialysis immediately before surgery, but the three most recent patients did not receive dialysis. We monitored plasma MMA levels and evaluated metabolic status during the perioperative period. Plasma MMA levels of patients who received preoperative dialysis were significantly decreased. However, lactic acidosis developed in two patients during surgery. One of the patients who had decreased renal function suffered from severe lactic acidosis after the transplantation and died on post operative day 44. In the three patients who did not receive preoperative dialysis, high plasma MMA levels persisted, but they did not develop metabolic decompensation. Their plasma MMA levels gradually decreased after transplantation. Our results indicated that reducing MMA with preoperative dialysis does not decrease the risk of metabolic decompensation. We will need to evaluate whether preoperative dialysis is necessary for the success of surgery with more cases in the future. Adequate perioperative glucose infusion and careful lactate monitoring are pivotal for success.Therapeutic apheresis and dialysis: official peer-reviewed journal of the International Society for Apheresis, the Japanese Society for Apheresis, the Japanese Society for Dialysis Therapy 10/2011; 15(5):488-92. · 1.39 Impact Factor -
Article: Identification of FOXP3-negative regulatory T-like (CD4(+)CD25(+)CD127(low)) cells in patients with immune dysregulation, polyendocrinopathy, enteropathy, X-linked syndrome.
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ABSTRACT: Immune dysregulation, polyendocrinopathy, enteropathy, X-linked (IPEX) syndrome is an autoimmune disorder caused by mutations in the FOXP3 gene, which plays a key role in the generation of CD4(+)CD25(+)regulatory T (Treg) cells. We selected CD127 as the surface marker of Treg cells to illustrate the development and function of Treg cells in IPEX syndrome. CD4(+)CD25(+)FOXP3(+) T cells, the putative Treg cells, were almost completely absent in all patients. Importantly, a substantial number of CD4(+)CD25(+)CD127(low) T cells were observed in 3 IPEX patients with hypomorphic mutations in the FOXP3 gene. We demonstrated that CD4(+)CD25(+)CD127(low) T cells isolated from these 3 patients exhibited an appreciable suppressive activity on effector T cell proliferation, although less than that displayed by Treg cells from healthy controls. These results suggest that genetically altered FOXP3 can drive the generation of functionally immature Treg cells, but that intact FOXP3 is necessary for the complete function of Treg cells.Clinical Immunology 07/2011; 141(1):111-20. · 4.05 Impact Factor -
Article: Living donor liver transplantation for multiple intrahepatic portosystemic shunts after involution of infantile hepatic hemangiomas.
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ABSTRACT: We describe a 6-year-old girl presenting with multiple intrahepatic portosystemic shunts after the involution of infantile hepatic hemangiomas (IHHs), who successfully underwent living donor liver transplantation. The chronological changes of radiologic findings indicated that remnant portovenous shunts at the time of IHHs involution developed gradually on the background of atrophic intrahepatic portal veins. This suggests that patients should be carefully followed up for the late onset of intrahepatic portosystemic shunts after the involution of IHHs.Journal of Pediatric Surgery 06/2011; 46(6):1288-91. · 1.45 Impact Factor -
Article: Aromatase excess syndrome: identification of cryptic duplications and deletions leading to gain of function of CYP19A1 and assessment of phenotypic determinants.
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ABSTRACT: Aromatase excess syndrome (AEXS) is a rare autosomal dominant disorder characterized by gynecomastia. Although cryptic inversions leading to abnormal fusions between CYP19A1 encoding aromatase and its neighboring genes have been identified in a few patients, the molecular basis remains largely unknown. The objective of the study was to examine the genetic causes and phenotypic determinants in AEXS. Eighteen affected males from six families participated in the study. We identified three types of heterozygous genomic rearrangements, i.e. a 79,156-bp tandem duplication involving seven of 11 noncoding CYP19A1 exons 1, a 211,631-bp deletion involving exons 2-43 of DMXL2 and exons 5-10 of GLDN, and a 165,901-bp deletion involving exons 2-43 of DMXL2. The duplicated exon 1 functioned as transcription start sites, and the two types of deletions produced the same chimeric mRNA consisting of DMXL2 exon 1 and CYP19A1 coding exons. The DMXL2 exon 1 harbored a translation start codon, and the DMXL2/CYP19A1 chimeric mRNA was identified in only 2-5% of CYP19A1-positive transcripts. This was in contrast to the inversion-mediated chimeric mRNA that had no coding sequence on the fused exon 1 and accounted for greater than 80% of CYP19A1-positive transcripts. CYP19A1 was expressed in a limited number of tissues, whereas its neighboring genes involved in the chimeric mRNA formation were expressed widely. This study provides novel mechanisms leading to gain of function of CYP19A1. Furthermore, it appears that clinical severity of AEXS is primarily determined by the tissue expression pattern of relevant genes and by the structural property of promoter-associated exons of chimeric mRNA.The Journal of clinical endocrinology and metabolism 04/2011; 96(6):E1035-43. · 6.50 Impact Factor -
Article: GATA3 abnormalities in six patients with HDR syndrome.
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ABSTRACT: GATA3 mutations cause HDR (hypoparathyroidism, sensorineural deafness, and renal dysplasia) syndrome and, consistent with the presence of the second DiGeorge syndrome locus (DGS2) proximal to GATA3, distal 10p deletions often leads to HDR and DiGeorge syndromes. Here, we report on six Japanese patients with GATA3 abnormalities. Cases 1-5 had a normal karyotype, and case 6 had a 46,XX,del(10)(p15) karyotype. Cases 1-6 had two or three of the HDR triad features. Case 6 had no DiGeorge syndrome phenotype except for hypoparathyroidism common to HDR and DiGeorge syndromes. Mutation analysis showed heterozygous GATA3 mutations in cases 1-5, i.e., c.404-405insC (p.P135fsX303) in case 1, c.700T>C & c.708-709insC (p.F234L & p.S237fsX303) on the same allele in case 2, c.737-738insG (p.G246fsX303) in case 3, c.824G>T (p.W275L) in case 4, and IVS5+1G>C (splice error) in case 5. Deletion analysis of chromosome 10p revealed loss of GATA3 and preservation of D10S547 in case 6. The results are consistent with the previous finding that GATA3 mutations are usually identified in patients with two or three of the HDR triad features, and provide supportive data for the mapping of DGS2 in the region proximal to D10S547.Endocrine Journal 01/2011; 58(2):117-21. · 2.03 Impact Factor -
Article: Living-donor liver transplantation for carbamoyl phosphate synthetase 1 deficiency.
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ABSTRACT: CPS1 is a mitochondrial matrix enzyme that catalyzes the first committed step of the urea cycle, the primary system for removing nitrogen produced by protein metabolism using N-acetylglutamate. Patients with CPS1 deficiency have severe hyperammonemia that results in serious neurologic sequelae and sometimes death. LT has been indicated for neonatal-onset CPS1 deficiency. This study retrospectively reviewed five children with a diagnosis of CPS1 deficiency who underwent LDLT from heterozygous donors. Between November 2005 and May 2010, 124 children underwent LDLT with an overall patient and graft survival of 91.0%. Five patients were indicated for LDLT because of CPS1 deficiency. All recipients achieved resolution of their metabolic derangement, without donor complication, with a normal feeding regimen without medication for their original metabolic liver disease. LDLT, even from heterozygous donors, appears to be a feasible option, associated with a better quality of life for treating patients with CPS1 deficiency. Long-term observation may therefore be necessary to collect sufficient data to confirm the efficacy of this treatment modality.Pediatric Transplantation 12/2010; 14(8):1036-40. · 1.48 Impact Factor -
Article: Androgenetic/biparental mosaicism in a girl with Beckwith-Wiedemann syndrome-like and upd(14)pat-like phenotypes.
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ABSTRACT: This report describes androgenetic/biparental mosaicism in a 4-year-old Japanese girl with Beckwith-Wiedemann syndrome (BWS)-like and paternal uniparental disomy 14 (upd(14)pat)-like phenotypes. We performed methylation analysis for 18 differentially methylated regions on various chromosomes, genome-wide microsatellite analysis for a total of 90 loci and expression analysis of SNRPN in leukocytes. Consequently, she was found to have an androgenetic 46,XX cell lineage and a normal 46,XX cell lineage, with the frequency of the androgenetic cells being roughly calculated as 91% in leukocytes, 70% in tongue tissues and 79% in tonsil tissues. It is likely that, after a normal fertilization between an ovum and a sperm, the paternally derived pronucleus alone, but not the maternally derived pronucleus, underwent a mitotic division, resulting both in the generation of the androgenetic cell lineage by endoreplication of one blastomere containing a paternally derived pronucleus and in the formation of the normal cell lineage by union of paternally and maternally derived pronuclei. It appears that the extent of overall (epi)genetic aberrations exceeded the threshold level for the development of BWS-like and upd(14)pat-like phenotypes, but not for the occurrence of other imprinting disorders or recessive Mendelian disorders.Journal of Human Genetics 11/2010; 56(1):91-3. · 2.57 Impact Factor -
Article: Novel intronic CYP21A2 mutation in a Japanese patient with classic salt-wasting steroid 21-hydroxylase deficiency.
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ABSTRACT: Congenital adrenal hyperplasia due to steroid 21-hydroxylase deficiency (21-OHD) is an autosomal recessive disorder caused by the defective CYP21A2 gene that leads to various degrees of impaired secretion of both cortisol and aldosterone. In the present study, we analyzed the CYP21A2 gene in a Japanese male patient with 21-OHD and functionally characterized the mutant CYP21A2 gene. The patient presented with hypoglycemia and a salt-losing crisis during the neonatal period, and was diagnosed as having the salt-wasting form of 21-OHD based on the clinical and laboratory findings. Analysis of the CYP21A2 gene revealed that the patient is homozygous for a novel C to A conversion at -9 position of intron 9 (IVS9-9C>A) and that his parents are heterozygous for the IVS9-9C>A mutation. Transient expression of the IVS9-9C>A mutant CYP21A2 gene in COS-1 cells demonstrated that the mutation creates an aberrant splice acceptor site at -7 position of intron 9 and totally inactivates the authentic splice acceptor site of intron 9, which results in complete deficiency of 21-hydroxylase activity and loss of immunoreactive 21-hydroxylase protein. Clinical presentations of the patient as the severe salt-wasting form of 21-OHD are in good agreement with these results of the expression study. In conclusion, the patient is a homozygote for the novel intronic IVS9-9C>A mutation, which affects messenger RNA splicing and totally inactivates 21-hydroxylase to give rise to clinically manifest classic salt-wasting 21-OHD.Metabolism: clinical and experimental 11/2010; 59(11):1628-32. · 2.59 Impact Factor -
Article: Identification and functional analysis of novel human growth hormone secretagogue receptor (GHSR) gene mutations in Japanese subjects with short stature.
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ABSTRACT: Short stature (SS) is a multifactorial developmental condition with a significant genetic component. Recent studies have revealed that rare deleterious mutations in the GH-secretagogue receptor type 1A (GHSR1A) gene could be a cause of familial SS or GH deficiency. The aim of this study was to evaluate the contribution of GHSR1A mutations to the molecular mechanism underlying SS in Japanese subjects. We performed mutational screening of the GHSR1A gene in 127 unrelated Japanese SS patients diagnosed with either isolated GH deficiency or idiopathic SS. Identified mutations were analyzed in 188 control subjects, and their functional properties were examined in a heterologous expression system. Four novel heterozygous GHSR1A mutations were identified (ΔQ36, P108L, C173R, and D246A). Expression studies demonstrated that these mutations had varying functional consequences: 1) all mutations showed a loss-of-function effect on the constitutive signaling activity of GHSR1A, but the degree of loss varied widely; 2) C173R caused intracellular retention of the mutated protein, resulting in total loss of receptor function; 3) P108L resulted in a large decrease in binding affinity to ghrelin, without affecting its surface expression; 4) D246A uniquely impaired agonist- and inverse agonist-stimulated receptor signaling; and 5) ΔQ36 showed only a subtle reduction in constitutive activity. The cumulative frequency of these putative functional mutations was significantly higher in the patient group than in controls (4.72 vs. 0.53%; P = 0.019; odds ratio = 9.28; 95% confidence interval, 1.10-78.0). Our results suggest that GHSR1A mutations contribute to the genetic etiology of SS in the Japanese population.The Journal of clinical endocrinology and metabolism 11/2010; 96(2):E373-8. · 6.50 Impact Factor -
Article: Identification and functional analysis of novel human growth hormone-releasing hormone receptor (GHRHR) gene mutations in Japanese subjects with short stature.
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ABSTRACT: Growth hormone-releasing hormone receptor (GHRHR) gene mutations have been identified in patients of different ethnic origins with isolated GH deficiency (IGHD) type IB. However, the prevalence of these mutations in the Japanese population has yet to be fully determined. This study aimed to evaluate the contributions of GHRHR mutations to the molecular mechanism underlying short stature in Japanese subjects. The GHRHR gene was sequenced in 127 unrelated Japanese patients with either IGHD (n = 14) or idiopathic short stature (ISS; n = 113). Sequence variants were evaluated in family members and 188 controls, and then examined in functional studies. A novel homozygous E382E (c.1146G>A) synonymous variant, at the last base of exon 12, was identified in an IGHD family with two affected sisters. In vitro splicing studies showed this mutation to result in skipping of exon 12. In one ISS patient, a heterozygous ATG-166T>C variant was found in the distal Pit-1 P2 binding element of the GHRHR promoter. In two control subjects, a close but distinct variant, ATG-164T>C, was detected. Functional studies showed that both promoter variants diminish promoter activity by altering Pit-1 binding ability. Four missense variants were also found in both patient and control groups but had no detectable functional consequences. The homozygous GHRHR mutation was rare, being detected in only one Japanese IGHD family. Future research is needed to clarify the genetic contributions of heterozygous functional promoter variants to GHD, ISS and normal-stature variations.Clinical Endocrinology 11/2010; 74(2):223-33. · 3.17 Impact Factor -
Article: A novel mutation (c.951C>T) in an exonic splicing enhancer results in exon 10 skipping in the human mitochondrial acetoacetyl-CoA thiolase gene.
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ABSTRACT: Mitochondrial acetoacetyl-CoA thiolase (T2) deficiency is an inherited disorder affecting isoleucine catabolism and ketone body metabolism. A Japanese female developed a severe ketoacidotic attack at the age of 7 months. Urinary organic acid analysis showed elevated excretion of 2-methyl-3-hydroxybutyrate but not tiglylglycine. She was diagnosed as having T2 deficiency by enzyme assay using fibroblasts. Mutation analysis revealed a compound heterozygote of c.556G>T(D186Y) and c.951C>T(D317D). Since c.951C>T does not cause amino acid change, we performed cDNA analysis and found that exon 10 skipping had occurred in the c.951C>T allele. A computer search using an ESE finder showed that an exonic splicing enhancer sequence, SF2/ASF, was located in CTGA(951)CGC. We hypothesized that the exonic splicing enhancer is necessary for accurate splicing since the first nucleotide of exon 10 is C, which weakens the splice acceptor site of intron 9. We made a mini gene construct including exon 9-truncated intron 9-exon 10-truncated intron 10-exon 11 for a splicing experiment. We also made three mutant constructs which alter the SF2/ASF site (947C>T, 951C>T, 952G>A). An min-gene splicing experiment clearly showed that exon 10 skipping was induced in all three mutant constructs. Moreover, additional substitution of G for C at the first nucleotide of exon 10 resulted in normal splicing in these three mutants. These results confirmed that c.951C>T diminished the effect of the exonic splicing enhancer and caused exon 10 skipping.Molecular Genetics and Metabolism 08/2010; 100(4):339-44. · 3.19 Impact Factor
Top co-authors
Top Journals
Institutions
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2003–2013
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National Research Institute for Child Health and Development
Tokyo, Tokyo-to, Japan
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2004–2011
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National Center for Child Health and Development
Tokyo, Tokyo-to, Japan -
Keio University
- Department of Pediatrics
Tokyo, Tokyo-to, Japan
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