title: [Clinical and laboratory screening studies on urea cycle defects].
abstract: OBJECTIVE
  To investigate the incidences of urea cycle defects (UCDs) in the patients with hyperammonemia and study their etiology, clinical and laboratory features.
  
  
  METHODS
  In the past 7 years, 26 cases (10.2%) of UCDs were detected from 254 patients with hyperammonemia. The etiological diagnoses were made by blood amino acids analysis, urinary organic acid analysis and blood acylcarnitine profile analysis. Three patients with citrullinemia type II were further confirmed by liver pathological analysis and gene diagnosis.
  
  
  RESULTS
  Among 26 cases with UCDs, 15 had ornithine transcarbamylase (OTC) deficiency, 5 had citrullinemia type I, 3 had citrullinemia type II and 3 patients had arginemia. The age of onset of the patients ranged from 3 days to 13 years. Three cases (11.5%) developed hyperammonemic encephalopathy during neonatal period. Thirteen (50.0%), 7 (26.9%) and 3 (11.5%) cases developed clinical symptoms at the age of 1 to 12 months, 1 to 3 years and 6 to 13 years, respectively. Positive family history was found in 11 cases (42.3%). Among 26 patients with UCDs, 9 (34.6%) were hospitalized with the complains of seizures, psychomotor retardation, vomiting and unconsciousness, 8 (30.8%) with recurrent vomiting, headache and coma, 6 due to liver dysfunction. Intrahepatic cholestatic jaundice was found in 3 patients with citrullinemia type II. Blood ammonia ranged from 58 to 259 micromol/L on their first visit to our hospital. Twenty cases (76.9%) had liver dysfunction, 4 patients (15.4%) were diagnosed postmortem. Twenty-one patients got treatment and were followed up. Among them, 7 cases died of hyperammonemic encephalopathy or upper alimentary tract bleeding. Clinical improvement was observed in 14 cases. A boy with OTC deficiency who received a partial liver transplant from his mother showed normal general condition for two years.
  
  
  CONCLUSIONS
  UCDs are the most frequent causes of congenital hyperammonemia. In this study, 26 patients (10.2%) with UCDs were identified from 254 patients with hyperammonemia resulting in encephalopathy and liver dysfunction. Early diagnosis and treatment can contribute a lot to improve the prognosis of the patients. Blood ammonia assay and further etiological analysis should be considered in the differential diagnosis of neurological and hepatic abnormality.
authors.affiliation: Department of Pediatrics, Peking University First Hospital, Beijing 100034, China.
authors.forename: Yan-ling
authors.initials: YL
authors.lastname: Yang
authors.forename: Fang
authors.initials: F
authors.lastname: Sun
authors.forename: Ning
authors.initials: N
authors.lastname: Qian
authors.forename: Jin-qing
authors.initials: JQ
authors.lastname: Song
authors.forename: Shuang
authors.initials: S
authors.lastname: Wang
authors.forename: Xing-zhi
authors.initials: XZ
authors.lastname: Chang
authors.forename: Hong-yun
authors.initials: HY
authors.lastname: Yang
authors.forename: Shu-qin
authors.initials: SQ
authors.lastname: Wang
authors.forename: Long
authors.initials: L
authors.lastname: Li
authors.forename: Yue-hua
authors.initials: YH
authors.lastname: Zhang
authors.forename: Xin-hua
authors.initials: XH
authors.lastname: Bao
authors.forename: Ming
authors.initials: M
authors.lastname: Li
authors.forename: Yu
authors.initials: Y
authors.lastname: Qi
authors.forename: Jiong
authors.initials: J
authors.lastname: Qin
authors.forename: Xi-ru
authors.initials: XR
authors.lastname: Wu
mesh_terms: D000293:Adolescent; D000641:Ammonia / Q000097:blood; D002648:Child; D002675:Child, Preschool; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D022124:Hyperammonemia / Q000151:congenital / Q000175:diagnosis* / Q000235:genetics; D007223:Infant; D007231:Infant, Newborn; D008297:Male; D014508:Urea / Q000378:metabolism*
chemical_list: D000641:Ammonia; D014508:Urea