遗传性酪氨酸血症Ⅰ型10例的临床诊断分析

2002年1月-2005年8月,我们通过对诊为新生儿或婴儿肝炎综合征的患儿临床高危筛查,确诊了遗传性酪氨酸血症Ⅰ型患儿10例,报告如下.     

遗传性酪氨酸血症Ⅰ型一例

患儿男 ,2个月 ,因皮肤黄染 2个月入院。患儿为第一胎第一产孕 40周因羊水过少剖宫产娩出 ,出生体重 2 30 0g。生后第二天皮肤黄染 ,逐渐加深 ,经白蛋白、蓝光照射等治疗后 ,皮肤黄疸消退。 3天后无明显诱因皮肤再度黄染伴贫血 ,经输浓缩红细胞、蓝光等治疗后黄疸减轻 ,无呕吐 ,大便淡黄色 ,体重增长欠佳。病情反复 ,曾多次住院治疗。父母非近亲婚配 ,否认家族性、遗传性疾病史。体检 :体重 3 2kg ,皮肤中度黄染 ,无皮疹 ,肝脏右肋下 3cm ,质软 ,脾脏左肋下 3cm ,质软。辅助检查 :血常规 :WBC1 3 3× 1 0 9/L ,N 0 68,L 0 32 ,Hb 82g/…     

Chromosomal instability in hereditary tyrosinemia type I

Autopsy of a 4-year-old girl with hereditary tyrosinemia type I revealed a hepatocellular carcinoma in addition to cirrhosis and renal tubular dysplasia. Cytogenetic studies performed on a skin fibroblast culture demonstrated greatly increased chromosome breakage, which affected 71% of the cells. This suggests that the development of hepatoma, which is frequent in this syndrome, and the presence of dysplastic changes of hepatocytes in nontumorous liver are related to genetic instability caused by accumulation of intermediates of tyrosine catabolism, which are natural alkylating agents (e.g., maleylacetoacetate and fumarylacetoacetate). The other microscopic structural changes seen, such as renal tubular atypia, pancreatic islet cell hyperplasia, and focal necrosis of cortical neurons, may also be partly due to DNA damage caused by the accumulation of abnormal metabolites produced in patients with type 1 tyrosinemia.     

晚发型遗传性酪氨酸血症Ⅰ型1例

遗传性酪氨酸血症I型（hereditarytyrosinemiatypeⅠ），又称肝肾型酪氨酸血症，属常染色体隐性遗传，是由于肝、肾组织中酪氨酸代谢的终末酶延胡索酰乙酰乙酸水解酶（FAH）缺陷，导致酪氨酸代谢障碍所致。本病发病率约为1／100000，多数患儿起病于新生儿或小婴儿期，肝功能受累显著。少数晚发型患儿通常起病于1岁以后，以生长发育迟缓、进行性肝硬化和肾小管功能受损等为主要表现。国内、外文献报道的遗传性酪氨酸血症Ⅰ型病例多以肝脏损害为主要表现，起病较早；以肾性佝偻病为主要表现的晚发型病例在国内尚未见报道。由于国内儿科对该病缺乏足够认识及受诊断技术的限制，误诊及漏诊率较高。本文报道起病于学龄前期，以肾性佝偻病为主要表现的晚发型遗传性酪氨酸血症Ⅰ型1例。[第一段]     

Serum type III procollagen in children with type I hereditary tyrosinemia.

BACKGROUND: Type I hereditary tyrosinemia leads to hepatic dysfunction and fibrosis and is associated with a high risk of hepatic malignancy. Serum N-terminal propeptide of type III procollagen is a sensitive marker of organ fibrosis of diverse origins. The current study was conducted to determine whether analysis of serum levels of type III procollagen in hereditary tyrosinemia would be useful in the follow-up of the progressive liver disease and eventually in detecting hepatic malignancy. METHODS: Serum N-terminal propeptide of type III procollagen was sequentially studied in 10 children with type I hereditary tyrosinemia. RESULTS: At diagnosis of type I hereditary tyrosinemia, serum N-terminal propeptide of type III procollagen ranged from 0.6 to 2.9 multiples of age-related median. During follow-up, serum N-terminal propeptide of type III procollagen decreased, yet remained elevated 0.2 to 2.6 years after diagnosis. Children with the acute type of the disease tended to have higher serum N-terminal propeptide of type III procollagen than did those with the chronic type. Porphyria crises were associated with elevated serum type III procollagen. The one patient receiving 2-(2-nitro-4-trifluoromethyl-benzoyl)-1,3-cyclohexanedione (NTBC) did not differ from the other ones in serum type III procollagen levels. Serum N-terminal propeptide of type III procollagen did not increase with developing hepatocellular carcinoma. CONCLUSIONS: Serum N-terminal propeptide of type III procollagen may be useful in monitoring the hepatopathy in type I hereditary tyrosinemia but is not useful in detecting malignant transformation in the liver.     

Liver transplantation for hereditary tyrosinemia type I: analysis of the UNOS database

Patients with HT-1 can develop progressive liver disease and have a high incidence of HCC. LT is indicated in patients with fulminant liver failure, HCC or decompensated chronic liver disease refractory to NTBC. To determine the need for LT and outcomes after LT in children with HT-1. Children with HT-1 who had LT between 10/1987 and 5/2008 were identified from the UNOS database. Of 11,467 children in the UNOS database, 125 (1.1%) required LT secondary to HT-1. Mean age at LT was two and half yr (s.d. ± 3.6 yr). Mean age at LT during the first 10 yr of the study (1.82, s.d. ± 2.86 yr) was significantly lower than in the last decade (3.70, s.d. ± 4.42 yr), p = 0.01. Nearly half of the patients (58, 46.4%) were transplanted between 1988 and 1992. Overall, one- and five-yr patient survival was 90.4% and 90.4%, respectively. LT is a valuable option for children with HT-1 with fulminant liver failure or when medical treatment fails. The rate of LT for children with HT-1 has decreased and age at transplant increased over the last decade most probably reflecting the effect of early diagnosis and treatment with NTBC.     

Live donor liver transplantation for type 1 tyrosinemia: An analysis of 15 patients

Type 1 tyrosinemia is a rare metabolic disorder of the tyrosine degradation pathway. Due to the rarity of the disease, the best evidence literature offers is limited to guidelines based on expert opinions and optimal treatment is still a debate. LT serves as a definitive treatment of the defective metabolic pathway in the liver along with other serious disease manifestations such as LF and HCC. Nitisinone is a relatively new agent that is currently recommended for the medical management of the disease. Its mechanism of action is well understood, and efficacy is well established when started presymptomatically. This study aims to evaluate outcomes of 15 patients with type 1 tyrosinemia who underwent LT in nitisinone era and discuss its effect on prevention of HCC. A LT database of 1037 patients was reviewed. Data from 15 patients with type 1 tyrosinemia were retrospectively analyzed. All the patients except one were treated with nitisinone prior to LT. Most common indications for LT were LF and suspicious nodules. Seven patients had HCC. Mortality rate was 20% (n = 3). Nitisinone treatment has opened new horizons in the management of type 1 tyrosinemia, but LT still remains the only option for the patients developing LF and in the event of HCC. Neonatal screening programs utilizing blood succinyl acetone as the marker should be encouraged especially in the countries, such as Turkey, with high prevalence of consanguineous marriages.     

Contribution of extrahepatic tissues to biochemical abnormalities in hereditary tyrosinemia type I: study of three patients after liver transplantation

Three patients with hereditary tyrosinemia type I were examined before and after liver transplantation to assess the role of extrahepatic tissues in the biochemical disorders of this disease. Before transplantation the three patients excreted excessive amounts of succinylacetoacetate (SAA), succinylacetone (SA), tyrosyl acidic compounds, and 5-aminolevulinate (ALA). The activity of 5-aminolevulinate dehydratase (ALA-D) in red blood cells was markedly inhibited (1% to 5% of control) in the three patients. Successful liver transplantation resulted in decreased excretion of urinary SAA plus SA, tyrosyl acidic compounds, and ALA. Two of the patients continued to excrete significant amounts of SAA plus SA, whereas those compounds were undetectable in the urine of the third patient. Tyrosine loading resulted in increased excretion of SAA plus SA in two patients, but those compounds remained undetectable in the third. All three patients continued to excrete higher than normal amounts of ALA, but the activity of ALA-D in red blood cells returned to normal after transplantation, indicating marked clearance of SA from the blood. Liver transplantation may not totally correct the biochemical abnormalities of hereditary tyrosinemia. It is likely that the kidney is the source of persistent biochemical aberrations in the urine without significant effects on the blood. Our results suggest the existence of heterogeneity for renal involvement in hereditary tyrosinemia.     

Kidneys of mice with hereditary tyrosinemia type I are extremely sensitive to cytotoxicity

Children with hereditary tyrosinemia type 1 (HT1) suffer from liver failure, renal tubular dysfunction, and rickets. The disease is caused by deficiency of fumarylacetoacetate hydrolase (FAH), the last enzyme of tyrosine catabolism, and leads to accumulation of the toxic substrate fumarylacetoacetate (FAA) in hepatocytes and renal proximal tubular cells. Patients are treated with 2-(2-nitro-4-trifluoro-methylbenzoyl)-1,3 cyclohexanedione (NTBC), which prevents accumulation of FAA by blocking an enzyme upstream of FAH. Liver transplantation is performed when patients do not respond to NTBC or develop hepatocellular carcinoma. This reduces the tyrosine load for the kidney but does not abolish renal exposure to locally produced FAA. To investigate the pathogenesis of liver and kidney damage induced by tyrosine metabolites, we challenged FAH-deficient mice with various doses of homogentisic acid (HGA), a precursor of FAA. Injecting NTBC-treated Fah-/- mice with low doses of HGA caused renal damage and death of renal tubular cells, as was shown by histologic analyses and deoxynucleotidyl transferase-mediated dUDP nick-end labeling (TUNEL) assay but did not lead to liver damage. In addition, kidney function, but not liver function, was affected after exposure to low doses of HGA. Administration of high doses of HGA led to massive cell death in both the liver and kidneys. Resistance to HGA-induced cell death was seen after withdrawing NTBC from Fah-/- mice. The finding that the kidneys of Fah-/- mice are especially sensitive to damage induced by low doses of HGA underscores the need to perform careful monitoring of the kidney function of tyrosinemia patients undergoing any form of treatment.     

Diagnosis and treatment of hereditary tyrosinemia in Japan

Hereditary tyrosinemia is an autosomal recessive inherited disease that manifests as three types (types I–III). We conducted a nationwide survey of this disease in Japan, and here review the results in relation to prevalence, clinical characteristics, and treatment and diagnosis. A definitive diagnosis of tyrosinemia type I is difficult to obtain based only on blood tyrosine level. Detection of succinylacetone using dried blood spots or urinary organic acid analysis, however, is useful for diagnosis. In tyrosinemia type I, dietary therapy and nitisinone (Orfandin®) are effective. Prognosis is greatly affected by the complications of liver cancer and hypophosphatemic rickets; even patients that are treated early with nitisinone may develop liver cancer. Long‐term survival can be expected in type I if nitisinone therapy is effective. Prognosis in types II and III is relatively good.     

Biochemical studies of a patient with hereditary hepatorenal tyrosinemia: evidence of glutathione deficiency

Metabolic and enzymatic studies in a patient with hereditary tyrosinemia demonstrated for the first time a deficiency of erythrocyte and hepatic glutathione. Markedly decreased hepatic fumarylacetoacetate hydrolase activity was demonstrated in this patient. The activities of hepatic enzymes not involved in tyrosine metabolism were also determined. Assay of mixed function oxidase activity demonstrated low levels of aryl hydrocarbon hydroxylase and 7-ethoxycoumarin deethylase, suggesting decreased hepatic detoxification capacity. 5-Aminolevulinic acid dehydratase activity was undetectable. Succinylacetone (4,6-dioxoheptanoic acid), an abnormal metabolic product secondary to fumarylacetoacetate hydrolase deficiency was found in serum and urine. Succinylacetone was demonstrated to inhibit 5-aminolevulinic acid dehydratase in vitro, as did the urine, plasma, and red cell lysates of the patient.     

Deficient fumarylacetoacetate fumarylhydrolase activity in lymphocytes and fibroblasts from patients with hereditary tyrosinemia

Fumarylacetoacetate fumarylhydrolase (E.C.3.7.1.2.), a liver enzyme involved in tyrosine degradation, is shown to be present in many human tissues and cells including lymphocytes, fibroblasts, and cultured amniotic fluid cells. The enzyme activity in lymphocytes from six patients with hereditary tyrosinemia (hepatorenal type) and fibroblasts from three patients, was found to be less than 10% of the activity in control subjects. In lymphocytes and fibroblasts from the parents (n = 16) of the patients the enzyme values were compatible with a heterozygote genotype. The lymphocyte enzyme pattern of the control subjects (n = 97), is complicated, and indicates possible enzyme variants.     

Favorable outcome of treatment with NTBC of acute liver insufficiency disclosing hereditary tyrosinemia type I]

BACKGROUND: Hereditary tyrosinemia type I is a disease with a severe prognosis. Main causes of death are acute liver failure, neurologic crises and hepatocarcinoma. NTBC, which acts as an inhibitor of the 4-hydroxyphenylpyruvate dioxygenase, prevents the formation of toxic metabolites involved in hepatic, renal and neurologic lesions. CASE REPORTS: Results of NTBC therapy used in three infants with type I tyrosinemia who presented with acute liver failure are reported. The diagnosis relied on the finding of high plasmatic levels of tyrosine and methionine, and abnormal urinary excretion of succinyl acetone and delta aminolevulinic acid. Treatment with NTBC was initiated within 2 to 8 days from onset of symptoms. Signs of liver failure resolved after 3 weeks therapy. After 12 to 39 months of follow-up, outcome remains favorable. CONCLUSION: The results reported here highlight the efficiency of NTBC in type I tyrosinemia with early acute onset. However, the long term outcome needs to be determined with regards to prevention of hepatocarcinoma and toxicity of the drug.     

Hereditary tyrosinemia type 1 from a single center in Egypt: clinical study of 22 cases

Background  

Hereditary tyrosinemia type 1 (HT1) is an increasingly recognized inborn error of metabolism among Egyptian children. This study was undertaken to define the presenting clinical, biochemical and imaging features and outcome of 2-(2-motrp-4-trifluoromethylbenzoyl)-1, 3-cyclohexanedione (NTBC) therapy and liver transplantation in a cohort of Egyptian children diagnosed with HT1.