Carbamoyl phosphate synthetase 1 (CPS1) and ornithine transcarbamylase (OTC) deficiencies are rare urea cycle disorders, which can lead to life-threatening hyperammonemia. Liver transplantation (LT) provides a cure and offers an alternative to medical treatment and life-long dietary restrictions with permanent impending risk of hyperammonemia. Nevertheless, in most patients, metabolic aberrations persist after LT, especially low plasma citrulline levels, with questionable clinical impact. So far, little is known about these alterations and there is no consensus, whether l-citrulline substitution after LT improves patients' symptoms and outcomes. In this multicentre, retrospective, observational study of 24 patients who underwent LT for CPS1 (n = 11) or OTC (n = 13) deficiency, 25% did not receive l-citrulline or arginine substitution. Correlation analysis revealed no correlation between substitution dosage and citrulline levels (CPS1, p = 0.8 and OTC, p = 1). Arginine levels after liver transplantation were normal after LT independent of citrulline substitution. Native liver survival had no impact on mental impairment (p = 0.67). Regression analysis showed no correlation between l-citrulline substitution and failure to thrive (p = 0.611) or neurological outcome (p = 0.701). Peak ammonia had a significant effect on mental impairment (p = 0.017). Peak plasma ammonia levels correlate with mental impairment after LT in CPS1 and OTC deficiency. Growth and intellectual impairment after LT are not significantly associated with l-citrulline substitution.
- MeSH
- amoniak metabolismus MeSH
- arginin terapeutické užití MeSH
- citrulin MeSH
- hyperamonemie * farmakoterapie MeSH
- karbamoylfosfát metabolismus terapeutické užití MeSH
- karbamoylfosfátsynthasa (amoniak) metabolismus MeSH
- lidé MeSH
- nemoc z nedostatku ornithinkarbamoyltransferázy * chirurgie MeSH
- ornithinkarbamoyltransferasa MeSH
- retrospektivní studie MeSH
- transplantace jater * MeSH
- Check Tag
- lidé MeSH
- Publikační typ
- časopisecké články MeSH
- multicentrická studie MeSH
- pozorovací studie MeSH
Článek shrnuje klinickou manifestaci, diagnostiku a léčbu poruch cyklu močoviny s důrazem na použití Arginin Chloridu v léčbě hyperamonémie. Na závěr přináší dvě kazuistiky nejčastější z poruch cyklu močoviny, deficitu ornithintranskarbamoylázy.
The text presents a short overview of clinical manifestation, diagnostics and therapy of urea cycle disorders, emphasises the role of Arginin chloride in the therapy of hyperammonemia. Two case reports of one of the most frequent type of urea cycle disorders, ornithin transcarbamylase deficiency, are presented at the end.
- MeSH
- arginin terapeutické užití MeSH
- hyperamonemie * diagnóza terapie MeSH
- lidé MeSH
- mladiství MeSH
- nemoc z nedostatku ornithinkarbamoyltransferázy * diagnóza patofyziologie terapie MeSH
- novorozenec MeSH
- ornithinkarbamoyltransferasa analýza MeSH
- výsledek terapie MeSH
- Check Tag
- lidé MeSH
- mladiství MeSH
- mužské pohlaví MeSH
- novorozenec MeSH
- Publikační typ
- kazuistiky MeSH
The most common ureagenesis defect is X-linked ornithine transcarbamylase (OTC) deficiency which is a main target for novel therapeutic interventions. The spf ash mouse model carries a variant (c.386G>A, p.Arg129His) that is also found in patients. Male spf ash mice have a mild biochemical phenotype with low OTC activity (5%-10% of wild-type), resulting in elevated urinary orotic acid but no hyperammonemia. We recently established a dried blood spot method for in vivo quantification of ureagenesis by Gas chromatography-mass spectrometry (GC-MS) using stable isotopes. Here, we applied this assay to wild-type and spf ash mice to assess ureagenesis at different ages. Unexpectedly, we found an age-dependency with a higher capacity for ammonia detoxification in young mice after weaning. A parallel pattern was observed for carbamoylphosphate synthetase 1 and OTC enzyme expression and activities, which may act as pacemaker of this ammonia detoxification pathway. Moreover, high ureagenesis in younger mice was accompanied by elevated periportal expression of hepatic glutamine synthetase, another main enzyme required for ammonia detoxification. These observations led us to perform a more extensive analysis of the spf ash mouse in comparison to the wild-type, including characterization of the corresponding metabolites, enzyme activities in the liver and plasma and the gut microbiota. In conclusion, the comprehensive enzymatic and metabolic analysis of ureagenesis performed in the presented depth was only possible in animals. Our findings suggest such analyses being essential when using the mouse as a model and revealed age-dependent activity of ammonia detoxification.
- MeSH
- amoniak metabolismus MeSH
- hyperamonemie genetika metabolismus patologie MeSH
- játra metabolismus patologie MeSH
- lidé MeSH
- močovina metabolismus MeSH
- modely nemocí na zvířatech MeSH
- myši transgenní MeSH
- myši MeSH
- nemoc z nedostatku ornithinkarbamoyltransferázy genetika metabolismus patologie MeSH
- ornithinkarbamoyltransferasa genetika MeSH
- stárnutí fyziologie MeSH
- věkové faktory MeSH
- zvířata MeSH
- Check Tag
- lidé MeSH
- mužské pohlaví MeSH
- myši MeSH
- zvířata MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
- přehledy MeSH
Ornithine transcarbamylase (OTC) deficiency is an X-linked disorder that causes recurrent and life-threatening episodes of hyperammonemia. The clinical picture in heterozygous females is highly diverse and derives from the genotype and the degree of inactivation of the mutated X chromosome in hepatocytes. Here, we describe molecular genetic, biochemical, and histopathological findings in the livers explanted from two female patients with late-onset OTC deficiency. Analysis of X-inactivation ratios by DNA methylation-based assays showed remarkable intra-organ variation ranging from 46:54 to 82:18 (average 70:30, n = 37), in favor of the active X chromosome carrying the mutation c.583G>C (p.G195R), in the first patient and from 75:25 to 90:10 (average 82:18, n = 20) in favor of the active X chromosome carrying the splicing mutation c.663+1G>A in the second patient. The X-inactivation ratios in liver samples correlated highly with the proportions of OTC-positive hepatocytes calculated from high-resolution image analyses of the immunohistochemically detected OTC in frozen sections that was performed on total area > 5 cm2. X-inactivation ratios in blood in both female patients corresponded to the lower limit of the liver values. Our data indicate that the proportion of about 20-30% of hepatocytes expressing the functional OTC protein is not sufficient to maintain metabolic stability. X-inactivation ratios assessed in liver biopsies taken from heterozygous females with X-linked disorders should not be considered representative of the whole liver.
- MeSH
- biopsie MeSH
- genotyp MeSH
- glutaminsynthetasa genetika metabolismus MeSH
- heterozygot MeSH
- inaktivace chromozomu X * MeSH
- játra enzymologie MeSH
- lidé MeSH
- lidské chromozomy X genetika MeSH
- nemoc z nedostatku ornithinkarbamoyltransferázy genetika MeSH
- ornithinkarbamoyltransferasa genetika metabolismus MeSH
- pohlavní dimorfismus MeSH
- Check Tag
- lidé MeSH
- mužské pohlaví MeSH
- ženské pohlaví MeSH
- Publikační typ
- časopisecké články MeSH
Deficit ornitintranskarbamoylázy (OTCD) je nejčastější dedičná porucha močovinového cyklu. Tato dědičná metabolická porucha (DMP) má gonozomálně recesivní typ dědičnosti a vzniká důsledkem nefunkčního enzymu ornitintranskarbamoylázy, která katalyzuje přeměnu ornitinu a karbamoylfosfátu na citrulin. Hromadící se toxický amoniak a další metabolity jsou hlavní příčinou klinické manifestace onemocnění, které se může projevit od novorozeneckého po dospělý věk. Autoři předkládají kazuistiku třináctiměsíčního chlapce hospitalizovaného pro apatii, celkovou hypotonii a hyperamonémii. Následná metabolická vyšetření prokázala deficit ornitintranskarbamoylázy, který byl potvrzen na molekulárně genetické úrovni.
Ornithine transcarbamylase deficiency (OTCD) is the most frequent inherited urea cycle disorder. This inherited metabolic disorder (IMD) has gonosomal recessive mode of inheritance and results from a deficiency of the mitochondrial enzyme ornithine transcarbamylase, which catalyses the conversion of ornithine and carbamoyl phosphate to citruline. The cumulation of toxic ammonia and other metabolites are the main cause of the earlier or later clinical manifestation of the disease. The authors present a case report of a thirteen-month-old boy who was taken to hospital due to apathy, overall hypotonia and hyperammonemia. Subsequent metabolic investigation showed the ornithine transcarbamylase deficiency that was confirmed at molecular genetic level.
- MeSH
- arginin terapeutické užití MeSH
- benzoáty terapeutické užití MeSH
- citrulin terapeutické užití MeSH
- fenylbutyráty terapeutické užití MeSH
- genetické testování MeSH
- hyperamonemie diagnóza terapie MeSH
- klinické enzymatické testy MeSH
- kojenec MeSH
- lidé MeSH
- mentální retardace MeSH
- nemoc z nedostatku ornithinkarbamoyltransferázy * diagnóza patofyziologie terapie MeSH
- nízkoproteinová dieta MeSH
- ornithinkarbamoyltransferasa metabolismus MeSH
- psychomotorické poruchy MeSH
- svalová hypotonie MeSH
- zvracení MeSH
- Check Tag
- kojenec MeSH
- lidé MeSH
- mužské pohlaví MeSH
- Publikační typ
- kazuistiky MeSH
- práce podpořená grantem MeSH
OTC encodes ornithine carbamoyltransferase, mitochondrial matrix enzyme involved in the synthesis of urea. The tissue-specific expression of OTC in the liver and intestine is dependent on the interaction of OTC promoter with an upstream enhancer. HNF-4 and C/EBPβ are crucial for this interaction in the rat and mouse. In the present study we focused on characterization of elements involved in the regulation of OTC transcription in human. Using a set of 5'-deleted promoter mutants in a reporter assay we identified two positive cis-acting regulatory elements located at c.-105 and c.-136 within the human OTC promoter. Both are essential for the transcriptional activity of the promoter itself and for the interaction with the enhancer. Protein binding at the corresponding sites was confirmed by DNase I footprinting. Electromobility shift assay with a specific competitor and anti-HNF-4α antibody identified the DNA-protein binding sites as HNF-4α recognition motifs. A third HNF-4α binding site has been found at the position c.-187. All three HNF-4α binding sites are located within 35 bp upstream of the transcription start sites at positions c.-95, c.-119 (major) and c.-169 (minor). A series of C/EBPβ recognition motifs was identified within the enhancer. Involvement of C/EBPβ and HNF-4α in the promoter-enhancer interaction is further supported by a massive DNAprotein interaction observed in the footprinting and EMSA assays. Since the OTC promoter lacks general core promoter elements such as TATA-box or initiators in standard positions, HNF-4α most likely plays an essential role in the initiation of OTC transcription in human.
- MeSH
- 5' přiléhající oblast DNA genetika MeSH
- buňky Hep G2 MeSH
- deoxyribonukleasa I metabolismus MeSH
- DNA footprinting MeSH
- DNA metabolismus MeSH
- genetická transkripce MeSH
- hepatocytární jaderný faktor 4 metabolismus MeSH
- krysa rodu rattus MeSH
- lidé MeSH
- luciferasy metabolismus MeSH
- molekulární sekvence - údaje MeSH
- mutace genetika MeSH
- myši MeSH
- ornithinkarbamoyltransferasa genetika metabolismus MeSH
- počítačová simulace MeSH
- promotorové oblasti (genetika) * MeSH
- regulace genové exprese enzymů * MeSH
- reportérové geny MeSH
- retardační test MeSH
- sekvence nukleotidů MeSH
- sekvenční seřazení MeSH
- vazba proteinů MeSH
- zvířata MeSH
- Check Tag
- krysa rodu rattus MeSH
- lidé MeSH
- myši MeSH
- zvířata MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
Ornithine carbamoyltransferase deficiency is the most common inherited defect of the urea cycle. We examined 28 male and 9 female patients from 29 families and identified 25 distinct mutations in OTC, 14 of which were novel. Three novel missense mutations (p.Ala102Pro, p.Pro158Ser, p.Lys210Glu) and a novel deletion of the Leu43 are not directly involved either in the enzyme active site or in the intersubunit interactions; however, the mutations include conserved residues involved in intramolecular interaction network essential for the function of the enzyme. Three novel large deletions - a 444 kb deletion affecting RPGR, OTC and TSPAN7, a 10 kb-deletion encompassing OTC exons 5 and 6 and a 24.5 kb-deletion encompassing OTC exons 9 and 10 - have probably been initiated by double strand breaks at recombination-promoting motifs with subsequent non-homologous end joining repair. Finally, we present a manifesting heterozygote carrying a hypomorphic mutation p.Arg129His in combination with unfavorably skewed X-inactivation in three peripheral tissues.
- MeSH
- alely MeSH
- amoniak krev MeSH
- dítě MeSH
- heterozygot MeSH
- kojenec MeSH
- lidé MeSH
- mladiství MeSH
- mladý dospělý MeSH
- mutace MeSH
- nemoc z nedostatku ornithinkarbamoyltransferázy diagnóza genetika MeSH
- novorozenec MeSH
- ornithinkarbamoyltransferasa genetika MeSH
- pořadí genů MeSH
- předškolní dítě MeSH
- rodina MeSH
- sekvence nukleotidů MeSH
- sekvenční delece MeSH
- Check Tag
- dítě MeSH
- kojenec MeSH
- lidé MeSH
- mladiství MeSH
- mladý dospělý MeSH
- mužské pohlaví MeSH
- novorozenec MeSH
- předškolní dítě MeSH
- ženské pohlaví MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
In a female patient with signs of ornithine carbamoyltransferase deficiency (OTCD), the only variation found was a heterozygous single nucleotide substitution c.-366A>G. Determination of transcription start sites of human OTC 95, 119 and 169 bp upstream of the initiation codon located the variation upstream of the 5'-untranslated region. We predicted the human promoter and enhancer elements from homology with rat and mouse, performed function analysis of both regulatory regions and assessed the impact of the promoter variation in functional studies using dual luciferase reporter assay. Our data indicate that: (i) Full transcriptional activity of human OTC promoter depends on an upstream enhancer, as do the rodent promoters. (ii) The promoter variation c.-366A>G does not affect the function of the promoter alone but it disrupts the interaction of the promoter with the enhancer. (iii) The promoter-enhancer interaction contributes to tissue specific expression of OTC in the liver. We conclude that mutations in the regulatory regions of OTC can lead to OTCD and should be included in genetic testing.
- MeSH
- buněčné linie MeSH
- kojenec MeSH
- lidé MeSH
- luciferasy metabolismus MeSH
- molekulární sekvence - údaje MeSH
- mutace genetika MeSH
- mutační analýza DNA MeSH
- nemoc z nedostatku ornithinkarbamoyltransferázy enzymologie genetika MeSH
- novorozenec MeSH
- ornithinkarbamoyltransferasa genetika MeSH
- počátek transkripce MeSH
- předškolní dítě MeSH
- promotorové oblasti (genetika) MeSH
- reportérové geny MeSH
- sekvence nukleotidů MeSH
- těhotenství MeSH
- zesilovače transkripce MeSH
- Check Tag
- kojenec MeSH
- lidé MeSH
- mužské pohlaví MeSH
- novorozenec MeSH
- předškolní dítě MeSH
- těhotenství MeSH
- ženské pohlaví MeSH
- Publikační typ
- časopisecké články MeSH
- kazuistiky MeSH
- MeSH
- dítě MeSH
- finanční podpora výzkumu jako téma MeSH
- hyperamonemie komplikace MeSH
- lidé MeSH
- metabolické nemoci mozku vrozené enzymologie genetika komplikace MeSH
- mutace MeSH
- nemoc z nedostatku ornithinkarbamoyltransferázy MeSH
- novorozenec MeSH
- ornithinkarbamoyltransferasa genetika MeSH
- Check Tag
- dítě MeSH
- lidé MeSH
- novorozenec MeSH
