• Childhood Kidney Diseases
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• v.25 no.2
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• pp.112-116
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• 2021

Hyperammonemia is mainly caused by diseases related to liver failure. However, there are also non-hepatic causes of hyperammonemia, such as urinary tract infection (UTI) due to urease-producing organisms. Urease production by these bacteria induces a hydrolysis of urinary urea into ammonia that can cross the urothelial cell membrane and diffuse into blood vessels, leading to hyperammonemia. Delayed diagnosis and treatment of hyperammonemia can lead to lethal encephalopathy that can cause brain damage and life-threatening conditions. In the presence of obstructive uropathy, UTI by urease-producing bacteria can lead to more severe hyperammonemia due to enhanced resorption of ammonia into the systemic circulation. In this report, we present a case of acute severe hyperammonemic encephalopathy leading to brain death due to accumulation of ammonia in blood caused by Morganella morganii UTI in a 10-year-old girl with cloacal anomaly, causing obstructive uropathy even after multiple corrections.

• Journal of Korean Neurosurgical Society
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• v.58 no.2
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• pp.159-162
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• 2015

Neurological deficits after brain surgery are not uncommon, and correct and prompt differential diagnosis is essential to initiate appropriate treatment. We describe a patient suffering from loss of consciousness due to hyperammonemia, following valproic acid treatment after surgery for an unruptured cerebral aneurysm. A 57-year-old female patient underwent successful aneurysmal neck clipping to correct an unruptured aneurysm. Her postoperative course was good, and she received anti-epileptic therapy (valproic acid) and a soft diet. Within a few days the patient experienced mental deterioration. Her serum valproic acid reached toxic levels (149.40 mg/L), and serum ammonia was fifteen times the upper normal limit (553 mmol/L; normal range, 9-33 mmol/L). After discontinuation of valproic acid and with conservative treatment, the patient recovered without any complications. Valproate-induced hyperammonemic encephalopathy is an unusual but serious neurosurgical complication, and should not be disregarded as a possible cause of neurological deficits after neurovascular surgery. Early diagnosis is crucial, as discontinuation of valproic acid therapy can prevent serious complications, including death.

• Journal of Yeungnam Medical Science
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• v.24 no.2
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• pp.322-328
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• 2007

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.

• Journal of The Korean Society of Inherited Metabolic disease
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• v.16 no.1
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• pp.34-41
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• 2016

Adult-onset type II citrullinemia (CTLN2) is characterized by episodes of neurologic symptoms associated with hyperammonemia leading to disorientation, irritability, seizures, and coma. CTLN2 is distinct from classical citrullinemia, which is caused by a mutation of the argininosuccinic acid synthetase (ASS) gene. The serum citrulline level is elevated, while the activity of ASS in liver tissue is decreased. CTLN2 is known to have a poor prognosis if the proper treatment is not taken. We reported a female aged 37 years who developed recurrent attacks of altered consciousness, aberrant behavior, and vomiting. We initially suspected the patient had CTLN2 because of the signs of hyperammonemic encephalopathy, such as altered mentality, memory disturbance, and aberrant behaviors provoked by exercise-induced stress and excessive intravenous amino acid administration. Through her peculiar diet preferences and laboratory findings that included hyperammonemia and citrullinemia, we diagnosed the patient as CTLN2, and SLC25A13 sequencing revealed known compound heterozygous mutations (IVS11+1G>A, c.674C> A). Her parents were heterozygous carriers, and we identified that her older sister had the same mutations. The older sister had not experienced any episodes of hyperammonemia, but she had peculiar diet preferences. The patient and her sister have been well with conservative management. When considering the clinical course of CTLN2, it was meaningful that the older sister could be diagnosed early in an asymptomatic period and that preemptive treatment was employed. Through this case, CTLN2 should be considered in adults who present symptoms of hyperammonemic encephalopathy without a definite etiology. Because of its rare incidence and similar clinical features, CTLN2 is frequently misdiagnosed as hepatic encephalopathy, and it shows a poor prognosis due to the lack of early diagnosis and proper treatment. A high-carbohydrate diet, which is usually used to treat other urea cycle defects, can also exaggerate the clinical course of CTLN2, so proper metabolic screening tests and genetic studies should be performed.

• Journal of The Korean Society of Inherited Metabolic disease
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• v.18 no.1
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• pp.18-22
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• 2018

Carbamoyl phosphate synthetase I (CPS1) deficiency is a rare autosomal recessive urea cycle disorder that causes hyperammonemic crisis. CPS1 is the first enzyme encoded by the CPS1 gene, which catalyzes the first step of the urea cycle. In CPS1 deficiency, ammonia, the toxic metabolite produced by the interruption of the urea cycle, is accumulated in the blood and brain, leading to hyperammonemic encephalopathy and irreversible brain damage. Here, we report a fatal case of neonatal-onset CPS1 deficiency in a 4-day-old girl presenting with recurrent seizures, who was revealed to be homozygous for c.1529delG ($p.Gly510Alafs^*5$).

• Journal of Genetic Medicine
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• v.7 no.1
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• pp.87-90
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• 2010

Asan Medical Center Children's Hospital, University of Ulsan College of Medicine, Seoul, Korea Hyperammonemia in the newborn often leads to severe fatal illness associated with hyperammonemic encephalopathy. Transient hyperammonemia in newborns (THAN) is characterized by self-limiting, transient hyperammonemia during the neonatal period. THAN may have favorable long-term outcomes if it is diagnosed early and appropriately managed. However, severe hyperammonemia can develop even in newborns with THAN, which may require emergent management. Here we report a case of THAN with severe hyperammonemia during the neonatal period that was successfully treated with continuous renal replacement therapy and nitrogen-scavenging medications. Our patient went on to develop normally and has not re-experienced a hyperammonemic episode until 9 months of age without the administration of a protein restricted diet or medications.