OBJECTIVETo detect potential mutations of OTC gene in a male infant affected with ornithine transcarbamylase deficiency.

METHODSGenomic DNA were isolated from peripheral blood samples of family members and 100 healthy individuals. Potential mutations of the 10 exons of OTC gene were screened with PCR and Sanger sequencing.

RESULTSA homozygous missense mutation c.917G>C in exon 9, which results in p.R306T, was identified in the infant. Sequencing of the mother and two female members of the family indicated a heterozygous status for the same mutation. The same mutation was not found in other members of the family and 100 healthy controls.

CONCLUSIONA missense mutation c.917G>C in the OTC gene is responsible for the pathogenesis of the disease. Identification of the mutation can facilitate prenatal diagnosis and genetic counseling for the family.

Computational Biology ; Female ; Humans ; Male ; Mutation ; Ornithine Carbamoyltransferase ; genetics ; Ornithine Carbamoyltransferase Deficiency Disease ; diagnosis ; genetics ; Sequence Analysis, DNA

Humans ; Urea Cycle Disorders, Inborn/diagnosis* ; Ornithine Carbamoyltransferase Deficiency Disease/diagnosis* ; China

PURPOSE: This study was undertaken to characterize molecular defects in Korean families with ornithine transcarbamylase(OTC) deficiency, correlate it with phenotype using in vitro expression study, and utilize it for making prenatal molecular diagnosis. METHODS: To investigate molecular lesions resulting in OTC deficiency in 15 unrelated Korean families, the OTC genes of probands were amplified exon by exon and analyzed by direct sequencing of double stranded DNA. Based on their molecular lesions, prenatal monitoring of six fetuses at risk from four unrelated families was performed using genomic DNA from chorionic villi sampling(CVS). To analyze expression in vitro, mutant OTC cDNAs were constructed and cotransfected with beta-galactosidase gene into COS-1 cells by using lipofection. After transient expression, OTC activity was measured by colorimetric method. RESULTS: Nine different mutations were identified in 10 out of 15 families ; six mutations were novel, involving well-conserved nucleotide sequences across species or CpG hot spot : T44I, M205T, H214Y, D249G, F281S, R320X. In vitro expression study revealed that the H214Y mutant showed a residual enzyme activity(13% vs 0% for D249G, 0% for R320X). However, clinical phenotype for H214Y was severe with neonatal onset. Three mutations were previously reported in other ethnic groups : R26Q, R141Q, R277W. Prenatal evaluation of 6 fetuses including one fraternal twins were successfully made. We predicted the outcome of all fetuses prenatally. They were also tested postnatally for the mutations to be unaffected. CONCLUSION: The genotypes of Korean patients with OTC deficiency are genetically heterogeneous. Therefore, molecular diagnosis should be individualized in each family with OTC deficiency.
Animals ; Base Sequence ; beta-Galactosidase ; Chorionic Villi ; COS Cells ; Diagnosis ; DNA ; DNA, Complementary ; Ethnic Groups ; Exons ; Fetus ; Genetic Association Studies* ; Genotype ; Humans ; Ornithine Carbamoyltransferase Deficiency Disease* ; Ornithine Carbamoyltransferase* ; Ornithine* ; Phenotype ; Prenatal Diagnosis ; Twins, Dizygotic

Ornithine transcarbamylase (OTC) deficiency is the most common inborn error of urea cycle metabolism; it is inherited in an X-linked manner. The OTC catalyzes the third step of the urea cycle, the conversion of ornithine and carbamyl phosphate to citrulline. Deficiency of OTC leads to the accumulation of ammonia, causing neurological deficits. In most affected hemizygote males, OTC deficiency manifests as hyperammonemic coma that often leads to death in the newborn period, and those who recover from the coma may be neurologically impaired due to the sequelae of the hyperammonemic encephalopathy. In some, late-onset manifestations develop. We report a male neonate with early onset OT deficiency that had apnea and was comatous. On mutation analysis using DNA sequencing after polymerase chain reaction (PCR) amplification of the 10 exons, deletions of 10 bases in codon 285, causing a frame shift was detected in exon 8. The mother and a sister were diagnosed as female carriers. Therefore, genetic counseling and the risk assessment could be provided to the family.
Ammonia ; Apnea ; Carbamyl Phosphate ; Citrulline ; Codon ; Coma ; Diagnosis* ; Exons ; Female ; Genetic Counseling ; Hemizygote ; Humans ; Infant, Newborn ; Male ; Metabolism ; Mothers ; Ornithine Carbamoyltransferase Deficiency Disease* ; Ornithine Carbamoyltransferase* ; Ornithine* ; Polymerase Chain Reaction ; Risk Assessment ; Sequence Analysis, DNA ; Siblings ; Urea

CT and MR appearance of the brain in three children with ornithine transcarbamylase (OTC) deficiency are described. They showed clinical signs of vomiting and convulsion and were diagnosed by measurement of plasma ammonium, amino acids, acid-base balance, and urinary orotic acid levels. CT and MR were performed within one month from the onset of the symptom. CT and MRI demonstrated brain swelling with small ventricles and diffuse low density of white matter, which indicated cerebral hypoperfusion secondary to elevated intracranial pressure. With more prolonged survival hyperammonemia may cause cerebral atrophy. CT and MR appearance in these cases resembled a hypoxic brain damage and this finding should be included in the differential diagnosis.
Acid-Base Equilibrium ; Amino Acids ; Ammonium Compounds ; Atrophy ; Brain ; Brain Edema ; Child ; Diagnosis, Differential ; Humans ; Hyperammonemia* ; Hypoxia, Brain ; Intracranial Hypertension ; Magnetic Resonance Imaging* ; Ornithine Carbamoyltransferase Deficiency Disease* ; Ornithine Carbamoyltransferase* ; Ornithine* ; Orotic Acid ; Plasma ; Seizures ; Vomiting

OBJECTIVE: Preimplantation genetic diagnosis (PGD) is reserved for couples with a risk of transmitting a serious and incurable disease, and hence avoids the undesirable therapeutic abortion. Herein, we report the result of PGD to carriers at risk of transmitting ornithine transcarbamylase (OTC) deficiency, junctional epidermolysis bullosa (EB) and lactic acidosis (LA) due to defect of pyruvate dehydrogenase alpha1 gene, respectively. METHODS: The ovarian stimulation, oocyte retrieval and ICSI procedure were undergone by conventional protocols. PGD for single gene disorders was carried out after biopsy of one or two blastomeres from the embryos on the third day. We performed the duplex nested PCR of the simultaneous amplification for the causative mutation loci as well as the SRY gene on Y chromosome in case of OTC deficiency and LA. Two different mutation loci of ITGB4 gene in EB case were amplified by the same protocol. The PCR products were analyzed by agarose gel electrophoresis, restriction fragment length polymorphism analysis or direct DNA sequencing. RESULTS: A total of 26 embryos were analyzed by duplex nested PCR. One or two blastomeres were biopsied, and successful diagnosis rate of PGD with PCR was 92.3% (24/26). There was no contamination in all PCR samples of negative controls (n=67). Five embryos (19.2%) were diagnosed as normal embryos, which were transferred to the mothers' uterus in each cases. In OTC deficiency case, singleton pregnancy was established. At 17 weeks of gestation, genetic normality of OTC gene in fetus was confirmed by amniocentesis. A healthy baby was successfully delivered at 36 weeks of gestation in OTC deficiency case. Unfortunately, pregnancies were not achievement in cases of EB and LA. CONCLUSION: This is the first report in Korea that healthy baby was born after specific PGD for OTC deficiency. Our results demonstrate that duplex nested PCR for single cell is an efficient method in identifying the gender and single gene mutation or two different mutation loci, simultaneously. This PGD procedure could provide normal healthy baby to the couple with a high risk of transmitting genetic diseases.
Abortion, Therapeutic ; Acidosis, Lactic* ; Amniocentesis ; Biopsy ; Blastomeres ; Diagnosis ; Electrophoresis, Agar Gel ; Embryonic Structures ; Epidermolysis Bullosa* ; Epidermolysis Bullosa, Junctional ; Family Characteristics ; Female ; Fetus ; Genes, sry ; Korea ; Oocyte Retrieval ; Ornithine Carbamoyltransferase Deficiency Disease* ; Ornithine Carbamoyltransferase* ; Ornithine* ; Ovulation Induction ; Oxidoreductases ; Polymerase Chain Reaction* ; Polymorphism, Restriction Fragment Length ; Pregnancy ; Preimplantation Diagnosis* ; Prostaglandins D ; Pyruvic Acid ; Sequence Analysis, DNA ; Sperm Injections, Intracytoplasmic ; Uterus ; Y Chromosome

Ornithine carbamoyltransferase (OTC) deficiency is a urea cycle disorder that causes the accumulation of ammonia, which can lead to encephalopathy. Adults presenting with hyperammonemia who are subsequently diagnosed with urea cycle disorders are rare. Herein, we report a case of a late-onset OTC deficient patient who was successfully treated with arginine, benzoate and hemodialysis. A 59-yr-old man was admitted to our hospital with progressive lethargy and confusion. Although hyperammonemia was suspected as the cause of the patient's mental changes, there was no evidence of chronic liver disease. A plasma amino acid and urine organic acid analysis revealed OTC deficiency. Despite the administration of a lactulose enema, the patient's serum ammonia level increased and he remained confused, leading us to initiate acute hemodialysis. After treatment with arginine, sodium benzoate and hemodialysis, the patient's serum ammonia level stabilized and his mental status returned to normal.
Age of Onset ; Ammonia/blood ; Arginine/therapeutic use ; Citrulline/blood ; Humans ; Hyperammonemia/*etiology ; Male ; Middle Aged ; Ornithine/blood ; Ornithine Carbamoyltransferase Deficiency Disease/complications/*diagnosis/drug therapy ; Pedigree ; Renal Dialysis ; Sodium Benzoate/therapeutic use

Urea cycle disorders are characterized by encephalopathy, respiratory alkalosis, and hyperammonemia. A urea cycle disorder should be considered a diagnostic possibility in any patient regardless of age with occult encephalopathy. The most common central nervous system pathology of urea cycle disorder is cerebral edema. The cerebral edema is caused by astrocyte swelling secondary to hyperammonemia and intracellular glutamine accumulation. Strokes in children occur in conjunction with cardiac disease, hematologic disorders, mitochondrial encephalopathy, trauma, intracranial infections and migraines. Recently, several inborn errors in metabolism have been recognized as possible causes of stroke. To our knowledge, there have been several reports on ornithine transcarbamylase deficiency with stroke. However, the case of citrullinemia presenting with a stroke-like episode has not been described previously. We report two infantile cases of citrullinemia with initial presentation of stroke. The differential diagnosis of unexplained strokes should include inborn errors of urea cycle metabolism during childhood.
Alkalosis, Respiratory ; Astrocytes ; Brain Edema ; Central Nervous System ; Child ; Citrullinemia* ; Diagnosis, Differential ; Glutamine ; Heart Diseases ; Humans ; Hyperammonemia ; Metabolism ; Migraine Disorders ; Mitochondrial Diseases ; Ornithine Carbamoyltransferase Deficiency Disease ; Pathology ; Stroke* ; Urea ; Urea Cycle Disorders, Inborn