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Patients with urea cycle disorders intermittently develop episodes of decompensation with hyperammonemia. Although such an episode is often associated with starvation and catabolism, its molecular basis is not fully understood. First, we attempted to elucidate the mechanism of such starvation‐associated hyperammonemia. Using a mouse embryonic fibroblast (MEF) culture system, we found that glucose starvation increases ammonia production, and that this increase is associated with enhanced glutaminolysis. These results led us to focus on α‐ketoglutarate (AKG), a glutamate dehydrogenase inhibitor, and a major anaplerotic metabolite. Hence, we sought to determine the effect of dimethyl α‐ketoglutarate (DKG), a cell‐permeable AKG analog, on MEFs and found that DKG mitigates ammonia production primarily by reducing flux through glutamate dehydrogenase. We also verified that DKG reduces ammonia in an NH4Cl‐challenged hyperammonemia mouse model and observed that DKG administration reduces plasma ammonia concentration to 22.8% of the mean value for control mice that received only NH4Cl. In addition, we detected increases in ornithine concentration and in the ratio of ornithine to arginine following DKG treatment. We subsequently administered DKG intravenously to a newborn pig with hyperammonemia due to ornithine transcarbamylase deficiency and found that blood ammonia concentration declined significantly over time. We determined that this effect is associated with facilitated reductive amination and glutamine synthesis. Our present data indicate that energy starvation triggers hyperammonemia through enhanced glutaminolysis and that DKG reduces ammonia accumulation via pleiotropic mechanisms both in vitro and in vivo. Thus, cell‐permeable forms of AKG are feasible candidates for a novel hyperammonemia treatment. [ABSTRACT FROM AUTHOR]

We report a case of a 13-year-old boy with arginase 1 deficiency carrying a new variant in ARG1. Sanger sequencing identified the compound heterozygous variants: NM_000045.4: c.365G>A (p.Trp122*)/c.820G>A (p.Asp274Asn). Although not previously reported, the p.Asp274Asn variant is predicted to have strong pathogenicity because it is located in a highly conserved domain in the protein core and arginase activity in the patient was below measurement sensitivity. [ABSTRACT FROM AUTHOR]

Importance: Sapropterin hydrochloride, a natural coenzyme (6R‐tetrahydrobiopterin) of phenylalanine hydroxylase, was first approved as a treatment for tetrahydrobiopterin deficiency in 1992 in Japan, and was then approved as a treatment for a tetrahydrobiopterin‐responsive hyperphenylalaninemia in 2007 and 2008, in the USA and Japan, respectively. Guidelines are required on the proper use of sapropterin hydrochloride for tetrahydrobiopterin‐responsive hyperphenylalaninemia. Observations: It is recommended that tetrahydrobiopterin‐responsive hyperphenylalaninemia should be diagnosed in all cases of hyperphenylalaninemia, including phenylketonuria, by tetrahydrobiopterin administration tests rather than by phenotype or blood phenylalanine levels. Conclusions and Relevance: If tetrahydrobiopterin‐responsive hyperphenylalaninemia is diagnosed, all ages can be treated with sapropterin hydrochloride. Although there are reports that sapropterin hydrochloride is effective and safe for the prevention of maternal phenylketonuria, further investigation is required. [ABSTRACT FROM AUTHOR]

Kabuki syndrome is a congenital anomaly syndrome characterized by developmental delay, intellectual disability, specific facial features including long palpebral fissures and ectropion of the lateral third of the lower eyelids, prominent digit pads, and skeletal and visceral abnormalities. Mutations in MLL2 and KDM6A cause Kabuki syndrome. We screened 81 individuals with Kabuki syndrome for mutations in these genes by conventional methods (n = 58) and/or targeted resequencing (n = 45) or whole exome sequencing (n = 5). We identified a mutation in MLL2 or KDM6A in 50 (61.7%) and 5 (6.2%) cases, respectively. Thirty-five MLL2 mutations and two KDM6A mutations were novel. Non-protein truncating-type MLL2 mutations were mainly located around functional domains, while truncating-type mutations were scattered through the entire coding region. The facial features of patients in the MLL2 truncating-type mutation group were typical based on those of the 10 originally reported patients with Kabuki syndrome; those of the other groups were less typical. High arched eyebrows, short fifth finger, and hypotonia in infancy were more frequent in the MLL2 mutation group than in the KDM6A mutation group. Short stature and postnatal growth retardation were observed in all individuals with KDM6A mutations, but in only half of the group with MLL2 mutations. © 2013 Wiley Periodicals, Inc. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

The mechanism underlying the development of osteopenia or osteoporosis in longstanding phenylketonuria (PKU) remains to be clarified. We investigated the details of bone metabolism in 21 female and 13 male classical PKU patients aged 20-35 years. Vitamin D (VD), parathyroid hormone (PTH), bone turnover markers, and daily nutrient intake were examined. The patients had lower daily energy and protein intake than did the age-matched controls (22 women, 14 men), but their respective fat, VD, and calcium intake did not differ. Serum 1,25-dihydroxy VD and 25-hydroxy VD levels in female and male patient groups were significantly higher and lower than those in respective control groups (females, P < 0.001; males, P < 0.05 and P < 0.01, respectively). Serum intact PTH levels were significantly higher in the female patient group (P < 0.05). Urinary calcium levels in the patient groups were significantly higher than those of the control subjects (females, P < 0.001; males, P < 0.05). Bone resorption markers were significantly higher in patients than in controls, although bone formation markers were not different. Patient serum levels of osteoprotegerin-inhibiting bone resorption were significantly lower (females, P < 0.001; males, P < 0.01). None of the bone parameters correlated significantly with serum phenylalanine or nutrient intake. PKU patients exhibited lower VD status and more rapid bone resorption despite normal calcium-VD intakes. [ABSTRACT FROM AUTHOR]

Recent studies suggest that refractory hypotension from causes other than septicaemia or cardiac failure is common in extremely preterm infants even out of the transitional period. Marked response to low-dose cortisol suggests underlying adrenal insufficiency, although the exact mechanism remains unknown. To investigate potential triggers for and related short-term outcomes of early-onset (

Background: Residual dried blood spots (DBS) remaining after routine newborn screening (NBS) tests are candidate specimens for extended uses such as quality assurance and the development of new technology. A trial of NBS using tandem mass-spectrometry was launched in 2004 in Japan. The aim of the present study was to analyze the attitudes of the public, patient families, and medical professionals toward the extended use and long-term storage of residual DBS, and to construct a standardized informational brochure. Methods: A questionnaire was sent to randomly selected members of the public, members of the Japanese Phenylketonuria (PKU) Association, medical staff of a general hospital, staff of a children's hospital, obstetricians and gynecologists, pediatricians and NBS personnel. Associated responses, which were given in a free comment format, were analyzed by text mining. Results: The awareness ratio of NBS was low in the public (26.6%), but despite this, when a brief explanatory note on NBS was provided, 71.7% of them recognized the necessity of NBS. They were less positive than medical professionals and PKU patient families regarding the extended use of DBS for forensic investigation, for the study of health problems, or long-term storage of residual DBS, regardless of whether these factors affected them personally or not. Among the medical professionals, obstetricians and pediatricians exhibited a higher ratio of negative responses toward the extended use and long-term storage of DBS than others. Conclusion: The general public is more conservative than PKU patients and their families or medical professionals about the extended use or long-term storage of residual DBS. Presentation to the public, particularly to couples of childbearing age, of appropriate explanatory information on NBS itself, or the extended use or long-term storage of residual DBS, is recommended. [ABSTRACT FROM AUTHOR]

Introduction: Ornithine transcarbamylase deficiency is the most common hereditary urea cycle defect. It is inherited in an X-linked manner and classically presents in neonates with encephalopathy and hyperammonemia in males. Females and males with hypomorphic mutations present later, sometimes in adulthood, with episodes that are frequently fatal.Case Presentation: A 13-year-old Caucasian girl presented with progressive encephalopathy, hyperammonemic coma and lactic acidosis. She had a history of intermittent regular episodes of nausea and vomiting from seven years of age, previously diagnosed as abdominal migraines. At presentation she was hyperammonemic (ammonia 477 μmol/L) with no other biochemical indicators of hepatic dysfunction or damage and had grossly elevated urinary orotate (orotate/creatinine ratio 1.866 μmol/mmol creatinine, reference range <500 μmol/mmol creatinine) highly suggestive of ornithine transcarbamylase deficiency. She was treated with intravenous sodium benzoate and arginine and made a rapid full recovery. She was discharged on a protein-restricted diet. She has not required ongoing treatment with arginine, and baseline ammonia and serum amino acid concentrations are within normal ranges. She has had one further episode of hyperammonemia associated with intercurrent infection after one year of follow up. An R40H (c.119G>A) mutation was identified in the ornithine transcarbamylase gene (OTC) in our patient confirming the first symptomatic female shown heterozygous for the R40H mutation. A review of the literature and correspondence with authors of patients with the R40H mutation identified one other symptomatic female patient who died of hyperammonemic coma in her late teens.Conclusions: This report expands the clinical spectrum of presentation of ornithine transcarbamylase deficiency to female heterozygotes for the hypomorphic R40H OTC mutation. Although this mutation is usually associated with a mild phenotype, females with this mutation can present with acute decompensation, which can be fatal. Ornithine transcarbamylase deficiency should be considered in the differential diagnosis of unexplained acute confusion, even without a suggestive family history. [ABSTRACT FROM AUTHOR]

We performed haplotype analysis using nine single nucleotide polymorphisms in the ornithine transcarbamylase gene to explore the ancestral origins of three mutations associated with late-onset phenotype in male patients: p.R40H, p.R277W and p.Y55D. Overall, 8 haplotypes were defined among 14 families carrying p.R40H, 5 families carrying p.R277W and 2 families with p.Y55D mutations. Of nine Japanese families carrying p.R40H, eight exhibited haplotype (HT)1, whereas the other family harbored HT2. Among three Caucasian families, one Spanish and one Australian family bore HT3; one Austrian family had HT4. Two US patients harbored HT2 and HT4. Among families carrying p.R277W, HT5 was found in one Japanese, one Korean and one US family. Two other US families had HT2 and HT6. Two families carrying p.Y55D, both Japanese, shared HT1. These results indicate that the p.R40H mutation has arisen recurrently in all populations studied, although there is evidence for a founder effect in Japan, with most cases probably sharing a common origin, and to a lesser extent in subjects of European ancestry (HT3). It is evident that p.R277W mutation has recurred in discrete populations. The p.Y55D mutation appears to have arisen from a common ancestor, because this transversion (c.163T>G) occurs rarely. [ABSTRACT FROM AUTHOR]

Mucolipidosis (ML) II alpha/beta and III alpha/beta are autosomal recessive diseases caused by a deficiency of α and/or β subunits of the enzyme N-acetylglucosamine-1-phosphotransferase, which is encoded by the GNPTAB gene. We analyzed the GNPTAB gene in 25 ML II and 15 ML III Japanese patients. In most ML II patients, the clinical conditions ‘stand alone’, ‘walk without support’ and ‘speak single words’ were impaired; however, the frequency of ‘heart murmur’, ‘inguinal hernia’ and ‘hepatomegaly and/or splenomegaly’ did not differ between ML II and III patients. We detected mutations in GNPTAB in 73 of 80 alleles. Fourteen new mutations were c.914_915insA, c.2089_2090insC, c.2427delC, c.2544delA, c.2693delA, c.3310delG, c.3388_3389insC+c.3392C>T, c.3428_3429insA, c.3741_3744delAGAA, p.R334L, p.F374L, p.H956Y, p.N1153S and duplication of exon 2. Previously reported mutations were p.Q104X, p.W894X, p.R1189X and c.2715+1G>A causing skipping of exon 13. Homozygotes or compound heterozygotes of nonsense and frameshift mutations contributed to the severe phenotype. p.F374L, p.N1153S and splicing mutations contributed to the attenuated phenotype, although coupled with nonsense mutation. These results show the effective molecular diagnosis of ML II and III and also provide phenotypic prediction. This is the first and comprehensive report of molecular analysis for ML patients of Japanese origin.Journal of Human Genetics (2009) 54, 145–151; doi:10.1038/jhg.2009.3; published online 6 February 2009 [ABSTRACT FROM AUTHOR]

In ten families with late-onset ornithine transcarbamylase (OTC) deficiency in male patients, three mutant alleles—R40H, R277W, and Y55D—were identified. In a total of 20 informative parent–offspring pairs, father-to-daughter transmission and mother-to-offspring transmission occurred in five (25%) and 15 (75%), respectively, indicating that paternal transmission contributes substantially to the pool of these mutant alleles. Relative reproductive fitness of males and females carrying the mutant alleles was calculated to be 0.49 and 0.89, respectively. Comparison of the life span of the mutant alleles, estimated on the basis of these fitness values with those associated with classic phenotype (neonatal onset) in which reproductive fitness of male patients was nil, revealed that mutant alleles associated with the late-onset phenotype were eliminated more slowly. This would allow the late-onset phenotype mutant alleles to be retained more frequently in a population than those associated with classic phenotype. Although heterozygous females carrying the late-onset phenotype mutant alleles were generally asymptomatic, one female carrying the R40H allele died after a hyperammonemic episode at the age of 18 years. Such heterozygous females should be alerted to possible hyperammonemic crisis. [ABSTRACT FROM AUTHOR]

Background: Gaucher disease type 1 and type 3 are characterized by bone disease and hematological symptoms. It is known that monocyte/macrophage lineage is activated in Gaucher disease, and accordingly certain cytokines are elevated in blood. The aim of the present study was to explore the possible relationships between cytokines and bone remodeling and hematological abnormalities in this disease. Methods: The concentrations of seven cytokines and two related proteins were measured in patients with Gaucher disease type 1 and type 3 ( n= 8; age range, 2–50 years) who had received enzyme replacement therapy. Results: Concentrations of interleukin-18 and transforming growth factor-β1 were elevated in patients of all clinical types. Elevation of these cytokines in Gaucher disease has not been previously reported. Analysis of correlation among cytokines and bone-turnover markers showed that interleukin-18 concentration was correlated with each of two bone formation markers of bone-specific alkaline phosphatase activity and osteocalcin concentration, whereas macrophage colony-stimulating factor concentration correlated with the bone absorption marker of N-telopeptide to helix in urine. Concentrations of macrophage colony-stimulating factor and tumor necrosis factor-α were inversely correlated with hemoglobin concentration. Conclusions: Interleukin-18 and monocyte macrophage colony-stimulating factor are cytokines mainly involved in the mechanism of bone disease, while macrophage colony-stimulating factor and tumor necrosis factor-α may play a role in the development of hematological abnormalities in Gaucher disease. [ABSTRACT FROM AUTHOR]

Isolated 3-methylcrotonyl-CoA carboxylase (MCC) deficiency appears to be the most frequent organic aciduria detected in tandem mass spectrometry (MS/MS) screening programs in the United States, Australia, and Europe. A pilot study of newborn screening using MS/MS has recently been commenced in Japan. Our group detected two asymptomatic MCC deficiency patients by the pilot screening and collected data on another three MCC deficiency patients to study the molecular bases of the MCC deficiency in Japan. Molecular analyses revealed novel mutations in one of the causative genes, MCCA or MCCB, in all five of the patients: nonsense and frameshift mutations in MCCA (c.1750C > T/c.901_902delAA) in patient 1, nonsense and frameshift mutations in MCCB (c.1054_1055delGG/c.592C > T) in patient 2, frameshift and missense mutations in MCCB (c.1625_1626insGG/c.653_654CA > TT) in patient 3, a homozygous missense mutation in MCCA (c.1380T > G/ 1380T > G) in patient 4, and compound heterozygous missense mutations in MCCB (c.569A > G/ c.838G > T) in patient 5. No obvious clinical symptoms were observed in patients 1, 2, and 3. Patient 4 had severe neurological impairment and patient 5 developed Reye-like syndrome. The increasing use of MS/MS newborn screening in Japan will further clarify the clinical and genetic heterogeneity among patients with MCC deficiency in the Japanese population. [ABSTRACT FROM AUTHOR]

Carbamoylphosphate synthetase I deficiency (CPS1D) is a urea-cycle disorder characterized by episodes of life-threatening hyperammonemia. Correct diagnosis is crucial for patient management, but is difficult to make from clinical presentation and conventional laboratory tests alone. Enzymatic or genetic diagnoses have also been hampered by difficult access to the appropriate organ and the large size of the gene (38 exons). In this study, in order to address this diagnostic dilemma, we performed the largest mutational and clinical analyses of this disorder to date in Japan. Mutations in CPS1 were identified in 16 of 18 patients with a clinical diagnosis of CPS1D. In total, 25 different mutations were identified, of which 19 were novel. Interestingly, in contrast to previous reports suggesting an extremely diverse mutational spectrum, 31.8% of the mutations identified in Japanese were common to more than one family. We also identified two common polymorphisms that might be useful for simple linkage analysis in prenatal diagnosis. The accumulated clinical data will also help to reveal the clinical presentation of this rare disorder in Japan. [ABSTRACT FROM AUTHOR]

Background: The occurrence of male patients with ornithine transcarbamylase (OTC) deficiency during adolescence or in adulthood has now been recognized. The aim of this study was to determine the prognostic factors that affect the prognosis of life, to explore a basis for therapeutic strategy. Methods: In 10 patients, nine of whom carried the R40H mutation and the other one carrying the Y55D mutation in the OTC gene, 32 demographic and laboratory data were first compared between survivors and non-survivors, using the unpaired t-test. The factors with significant difference were then subjected to multiple regression analysis. Results: The factors that exhibited significant difference were: age at onset, concentration of plasma ammonium, blood pH, and concentrations of six amino acids in plasma. The multiple regression analysis then revealed concentrations of ammonium, leucine, lysine, isoleucine, phenylalanine, glutamine and proline to be significant prognostic factors. The amino acid profile in the 10 patients showed increases in glutamine, proline, lysine, valine and methionine, and decreases in serine, ornithine and arginine. There was an inverse correlation between the age at onset and the level of the residual hepatic OTC activity. Conclusion: The results implied that: (i) the plasma amino acid profile was unique, in comparison to other liver diseases; (ii) the plasma concentration of each of the (mentioned above) six amino acids was a significant predictor of prognosis; and (iii) suppression of protein catabolism, as suggested by the higher concentrations in isoleucine and leucine in the non-survivors, prevention of glutamine-induced brain edema, correction of alkalosis, and supplementation with ornithine or arginine may improve the prognosis of life. [ABSTRACT FROM AUTHOR]

Carbon molecular sieving membranes were prepared by pyrolysis of lignocresol derived from lignin by the phase-separation method. Lignocresol membranes formed by a dip process on a porous α-alumina tubing were carbonized at 400–800°C under nitrogen atmosphere. The thickness of the membrane formed on the outer surface of the substrate was about 400 nm judging from SEM observation. Gas-evolving behavior of lignocresol was measured using thermogravimetry-mass spectrometry (TG-MS). The gaseous products evolved from lignocresol included a number of fragments with higher molecular weights; whereas those from phenolic resin are mainly due to phenol and methylphenol. These evolved pyrolysis fragments effectively contribute to micropore formation of carbonized lignocresol membranes. Gas permeation rates through the membrane decreased in the order of increasing kinetic molecular diameter of the penetrant gas, and the membrane behaved like a “molecular sieve.” The permeation properties were dependent on heating conditions, and a pyrolysis temperature of 600°C gave the best membrane performance. Gas selectivities of the membrane prepared at 600°C were 50, 8, 290, and 87 for CO2/N2, O2/N2, H2/CH4, and CO2/CH4 at 35°C, respectively. [ABSTRACT FROM AUTHOR]

Examines the management of acute metabolic decompensation in maple syrup urine disease (MSUD). Clinical phenotypes of MSUD; Therapeutic measures employed toward metabolic decompensation; Number of patients in the study who developed episodes of ketoacidosis during the neonatal period.

Primary systemic carnitine deficiency (SCD; OMIM 212140) is an autosomal recessive disorder characterized by progressive cardiomyopathy, skeletal myopathy, hypoglycaemia and hyperammonaemia. SCD has also been linked to sudden infant death syndrome. Membrane-physiological studies have suggested a defect of the carnitine transport system in the plasma membrane in SCD patients and in the mouse model, juvenile visceral steatosis (jvs; ref. 6). Although the responsible loci have been mapped in both human and mouse, the underlying gene has not yet been identified. Recently, we cloned and analysed the function of a novel transporter protein termed OCTN2 ( ref. 9). Our observation that OCTN2 has the ability to transport carnitine in a sodium-dependent manner prompted us to search for mutations in the gene encoding OCTN2, SLC22A5. Initially, we analysed the mouse gene and found a missense mutation in Slc22a5 in jvs mice. Biochemical analysis revealed that this mutation abrogates carnitine transport. Subsequent analysis of the human gene identified four mutations in three SCD pedigrees. Affected individuals in one family were homozygous for the deletion of a 113-bp region containing the start codon. In the second pedigree, the affected individual was shown to be a compound heterozygote for two mutations that cause a frameshift and a premature stop codon, respectively. In an affected individual belonging to a third family, we found a homozygous splice-site mutation also resulting in a premature stop codon. These mutations provide the first evidence that loss of OCTN2 function causes SCD. [ABSTRACT FROM AUTHOR]

We report the case of a family with late-onset ornithine transcarbamylase deficiency ( OTCD). Several family members had died from OTCD, and the c. 221G>A, p. Lys221 Lys mutation was detected at the 3′ end of exon 6 of OTC in the X-chromosome of some members. We provided genetic counseling on pregnancy, delivery, and neonate management to a 4th-generation female carrier and decided on metabolic management of her child from birth. Two male patients were diagnosed with late-onset OTCD on the basis of blood amino acid and genetic analysis, and they received arginine supplementation from the asymptomatic, early neonatal period. These children grew and developed normally, without decompensation. Patients with late-onset OTCD can and should be diagnosed and treated in the early neonatal period, especially those from families already diagnosed with late-onset OTCD, and family members must be provided with genetic counseling. [ABSTRACT FROM AUTHOR]