Early liver transplantation is indicated for tyrosinemia type I

Liver transplantation is now accepted as the treatment of choice for tyrosinemia type I (hereditary tyrosinemia). In an effort to determine whether any factors in these patients would aid in predicting optimal timing of the transplant procedure, we evaluated several clinical, biochemical, and radiographic parameters in five successive patients undergoing liver transplant for tyrosinemia type I at the University of Minnesota. All five patients evidenced prolonged periods of clinical and metabolic stability with dietary therapy and four of five remained stable at the time of evaluation for transplantation. Nevertheless, all five suffered significant and unexpected complications of tyrosinemia prior to the time of liver transplant. Four developed renal stones, two were in liver failure, and one developed a neurologic crisis that left him completely paralyzed. Hepatocellular carcinoma was found in one of the five at transplant. We could identify no clinical, biochemical, or radiographic study that was predictive of the likelihood of significant complications of the disorder. Survival from the transplant procedure itself was 100%. The inability to predict or prevent significant complications of tyrosinemia and the favorable outcome from transplantation lead us to recommend liver transplant for all patients with tyrosinemia type I by 12 months of age.     

The occurrence of hepatoma in the chronic form of hereditary tyrosinemia.

A 5 1/2-year-old child with hepatocarcinoma complicating hereditary tyrosinemia is presented. A review of the literature and an attempted follow-up of previously reported patients with the chronic form of hereditary tyrosinemia have disclosed 16 cases of hepatocarcinoma occurring in 43 patients surviving beyond 2 years of age (37%). This incidence is considerably higher than that generally given for the occurrence of hepatoma in adults with macronodular cirrhosis. Females and males are equally at risk. Additional factors beyond the development of cirrhosis are likely operative in the induction of hepatocarcinoma in patients with this metabolic disorder; those surviving beyond infancy are at considerable risk for the development of fatal hepatic neoplasms.     

Succinylacetone and delta-aminolevulinic acid dehydratase in hereditary tyrosinemia: immunochemical study of the enzyme

Immunochemical determinations of delta-aminolevulinic acid (ALA) dehydratase were performed in erythrocytes and in liver of a patient with hereditary tyrosinemia who underwent liver transplantation for correction of this metabolic disorder. Both erythrocytic and hepatic ALA dehydratase activities were extremely low before liver transplantation, but they appeared normal after transplantation. According to results of immunochemical quantification of ALA dehydratase, the level of the enzyme protein in erythrocytes was not different before, during, and after liver transplantation. Immunoquantifiable enzyme concentrations were not substantially different in the patient's own liver as compared with the transplanted liver. These findings indicate that although succinylacetone, an abnormal metabolite produced in tyrosinemia, is a potent inhibitor of the activity of ALA dehydratase, it has a far less effect on the synthesis of the enzyme protein.     

Tyrosinemia: A Review

Hypertyrosinemia encompasses several entities, of which tyrosinemia type I (or hepatorenal tyrosinemia, HT1) results in the most extensive clinical and pathological manifestations involving mainly the liver, kidney, and peripheral nerves. The clinical findings range from a severe hepatopathy of early infancy to chronic liver disease and rickets in the older child; gradual refinements in the diagnosis and medical management of this disorder have greatly altered its natural course, mirroring recent advances in the field of metabolic diseases in the past quarter century. Hepatorenal tyrosinemia is the inborn error with the highest incidence of progression to hepatocellular carcinoma, likely due to profound mutagenic effects and influences on the cell cycle by accumulated metabolites. The appropriate follow-up of patients with cirrhosis, the proper timing of liver transplantation in the prevention of carcinoma, and the long-term evolution of chronic renal disease remain important unresolved issues. The introduction of a new pharmacologic agent, NTBC, holds the hope of significantly alleviating some of the burdens of this disease. Mouse models of this disease have permitted the exploration of newer treatment modalities, such as gene therapy by viral vectors, including ex vivo and in utero methods. Finally, recent observations on spontaneous genetic reversion of the mutation in HT1 livers challenge conventional concepts in human genetics. Received November 15, 2000; accepted December 7, 2000.     

Hereditary tyrosinemia type I: lack of correlation between clinical findings and amount of immunoreactive fumarylacetoacetase protein.

Immunoblot analyses with bovine fumarylacetoacetase antibodies have been performed in fibroblast extracts from 28 patients with hereditary tyrosinemia of various clinical phenotypes, in one healthy individual homozygous for a "pseudodeficiency" gene for fumarylacetoacetase, and in three tyrosinemia families in which one or both parents are compound heterozygotes for the tyrosinemia and pseudodeficiency genes. Liver extracts from two chronic patients were also investigated. None of the patients with the acute type of tyrosinemia had detectable immunoreactive protein in fibroblast extracts. Only two of seven patients with typical chronic tyrosinemia had definite immunoreactivity in fibroblasts. In liver tissue, one of the patients had cross-reactive material and the other had no immunoreactivity. Four of 13 patients with intermediate clinical findings showed immunoreactivity in fibroblasts. There was no relationship between severity of symptoms and amount of cross-reactive material in this group. The pseudodeficiency gene product gave almost no detectable immunoreactivity in fibroblasts. The results indicate that chronic tyrosinemia may be due to at least two protein variants, and immunoblotting does not classify tyrosinemia patients according to clinical findings.     

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.     

Prenatal diagnosis of hereditary tyrosinemia by determination of fumarylacetoacetase in cultured amniotic fluid cells

Fumarylacetoacetase was assayed in cultured amniotic fluid cells from four pregnancies at risk for hereditary tyrosinemia and in 11 controls. The enzyme activity was normal in three of the pregnancies at risk for tyrosinemia and healthy children were born. In the fourth case the enzyme activity was deficient, indicating an affected fetus. As the pregnancy was very advanced it was continued, and the child has tyrosinemia. One parent in one of the four families is a compound heterozygote for the tyrosinemia gene and the recently reported "pseudodeficiency" gene for fumarylacetoacetase. This has important consequences for prenatal diagnosis in this family.     

Diagnostic Problems of Disorders of Tyrosine Metabolism

Abnormalities of tyrosine metabolism have been reported in infants and children with a variety of liver diseases. Especially infants with hereditary fructose intolerance show often the very similar picture of clinical symptoms with congenital tyrosinemia. The livers of the patients, two cases of congenital tyrosinemia type 1 and three cases of hereditary fructose intolerance, were studied biochemically and compared to normal control livers. Kinetic studies of p-hydroxyphenylpyruvate oxidase revealed that crude extract of livers from patients with congenital tyrosinemia were distinctively inhibited by substrate in low concentration. It is suggested that this kinetic abnormality is closely related to the fundamental defect of congenital tyrosinemia. Activity of p-hydroxyphenylpyruvate oxidase was noted in peripheral leucocytes. The patient showed a reduced activity as low as 20% of normal. Enzyme assay in leucocytes might be useful in making the definite diagnosis prior to starting correct diagnosis for tyrosinemic state.     

Evolution of a case of tyrosinemia type I treated with NTBC

Tyrosinemia type I is an autosomal recessive inherited disorder caused by deficient fumarylacetoacetase activity. Treatment with 2-(2-nitro-4-trifluoro-methylbenzoyl)-1,3-cyclohexanedione (NTBC), an inhibitor of 4-hydroxyphenylpyruvate dioxygenase, has successfully been applied for the last few years. Our aim was to evaluate the clinical and biochemical response to treatment with NTBC of a 18-year-old patient with a chronic form of tyrosinemia type I, whose main clinical feature was vitamin D-resistant rickets leading to severe osteoporosis with multiple bone fractures and skeletal deformities. After treatment, toxic metabolites became undetectable and porphobilinogen synthase activity returned to normal. Renal function improved, blood hemoglobin returned to normal and alfa-fetoprotein decreased. The patient's general condition greatly improved. However, the alfa-fetoprotein concentration slowly increased during the second year of NTBC treatment and hepatocellular carcinoma developed. NTBC treatment should be considered even in advanced cases of tyrosinemia type I, although only as a palliative therapy.     

HEREDITARY TYROSINEMIA

The clinical and biochemical findings in the case of an infant with hereditary tyrosinemia followed from birth have been reported. The child received a low protein diet from birth and a formula diet restricted in phenylalanine and tyrosine when the diagnosis was established at 54 days of age. There was a steady progress of the disease and the baby died from liver failure complicated with septicemia when he was 5½ months old. The clinical course and the biochemical findings as well as the morphological changes were typical of the acute type of the disease. A 6½ year old brother suffers from the same disease of the chronic type and the two types of hereditary tyrosinemia therefore seem to belong to the same genotype. The biochemical data from the patient with hereditary tyrosinemia have been compared with those in a healthy looking baby with longstanding and pronounced transient tyrosinemia of early infancy. The patterns of amino acids in blood and of phenolic acids in urine were similar in the two patients and it is concluded that an early laboratory differential diagnosis between hereditary tyrosinemia and transient tyrosinemia may only be made by observing the biochemical response to a diet restricted in tyrosine and phenylalanine in combination with the results of phenylalanine tolerance tests. The clinical features of hereditary tyrosinemia can apparently not be attributed to a high serum-tyrosine concentration or to the overproduction of phenolic acids; the lack of effect of early restriction in the intake of phenylalanine and tyrosine indicates a more complex pathogenesis of hereditary tyrosinemia than a primary deficiency of p-hydroxyphenylpyruvate hydroxylase.     

Enzyme defect in a case of tyrosinemia type I, acute form

We determined the activities of tyrosine aminotransferase (TAT, EC 2.6.1.5), p-hydroxyphenylpyruvate oxidase (p- HPPA oxidase, EC 1.14.2.2) and fumarylacetoacetate fumarylhydrolase ( FAH , EC 3.7.12) in cytosol of the liver and kidney tissues obtained at autopsy from a case of hereditary tyrosinemia type I. Values were compared with those from a control group of autopsied tissues from three adults and six children, who had died of other causes. In tyrosinemia, these three hepatic enzyme activities were all decreased: TAT showed approximately 35%, p- HPPA oxidase 11%, and FAH 60% of the corresponding control values. On the other hand, kidney enzymes in tyrosinemia revealed that FAH was most significantly decreased to approximately 14% of the control activity. Km values for substrate--determined for p- HPPA oxidase and FAH --were not different between the patient and controls, suggesting no altered properties of these enzymes. We conclude that in the present case of hereditary tyrosinemia type I, the activities of p- HPPA oxidase in liver and FAH in kidney were most strikingly affected. This fact may in part explain the deteriorated metabolism of tyrosine observed in this patient.     

Rapid improvement in the renal tubular dysfunction associated with tyrosinemia following hepatic replacement.

The postoperative management of patients with hereditary tyrosinemia type I (McKusick 27670) following liver transplantation is often complicated by the renal tubular dysfunction associated with this disease. To characterize better the temporal course of the improvement in renal excretory activity following hepatic replacement, renal tubular function and metabolite excretion were studied in a 4-year-old girl with hereditary tyrosinemia during the immediate post-transplantation course. Tubular reabsorption of bicarbonate and phosphate were normal 5 days following transplantation, in contrast to glucosuria, hyperaminoaciduria, and tyrosyluria, which persisted for approximately 3 weeks. After hepatic replacement, serum amino acid concentrations returned to normal and succinylacetone was no longer detected in the urine. This is the third tyrosinemia patient reported to achieve complete resolution of urinary abnormalities following transplantation, and the only patient in whom renal tubular function was formally assessed within the first postoperative week.     

Tyrosinemia type I: A clinico-laboratory case report

Progressive hepatocellular dysfunction in a neonate, resulting in elevated serum α-fetoprotein together with raised blood levels of tyrosine and methionine, a generalized amino aciduria and the absence of urinary δ-aminolevulinic acid and succinylacetone, suggests a diagnosis of tyrosinemia type Ib. Classical tyrosinemia type I arises from a deficiency of fumarylacetoacetate hydrolase while the variant tyrosinemia type Ib results from a deficiency of maleylacetoacetate isomerase.     

Tyrosinemia type I—Diagnostic issues and prenatal diagnosis

A fifteen-month-old boy, born to consanguineously married couple, presented with asymptomatic hepatomegaly. Investigations revealed midly deranged liver functions, necroinflammatory changes and cirrhosis on liver biopsy, a markedly raised alpha feto protein and tyrosine levels in plasma and a generalized aminoaciduria. His diagnosis of hereditary tyrosinemia was established on findings of raised serum and urine succinylacetone, and a deficient activity of fumaryl acetoacetate hydroxylase enzyme. Prenatal diagnosis of hereditary tyrosinemia was performed in a subsequent pregnancy in this family from India.     

A rare cause of neonatal hyperphenylalaninemia: tyrosinemia type I]

Phenylalanine, the direct precursor of tyrosine, is rarely increased in tyrosinemia I. We report on a case of tyrosinemia type I diagnosed through neonatal hyperphenylalaninemia. This case report points out the need for a biological evaluation of the hepatic function in cases of neonatal hyperphenylalaninemia.     

The efficacy of liver transplantation in malignant liver tumors associated with tyrosinemia: clinical and laboratory findings of five cases

To evaluate clinical and laboratory findings of these patients and the efficacy of liver transplantation in children with hepatocellular carcinoma (HCC) and hepatoblastoma (HB) associated with tyrosinemia. Among 113 children with liver tumors diagnosed between 1972 and 2004 five patients had HCC or HB associated with tyrosinemia. The age at diagnosis of the HCC or HB ranged from 9.5 to 17 yr and male:female ratio was 1:4. During regular clinic visits for tyrosinemia, elevated alpha-fetoprotein (AFP) was detected in all patients. AFP levels ranged between 13.7 and 29 340 IU/mL. Radiological studies including ultrasound, computed tomography and magnetic resonance imaging showed heterogeneous parenchyma and nodules in the liver. The patients did not have any metastatic disease. The time from diagnosis of tyrosinemia to HCC or HB ranged from 9.25 to 15.25 yr. Histopathologically, four patients have been diagnosed as HCC and one patient had HB. All patients were given chemotherapy including cisplatin and adriamycin. In three patients, living-related liver transplantation was performed. They had no treatment after transplantation. All of them are disease free. One patient was treated with chemotherapy and right hepatectomy. She had no suitable donor for living-related liver transplantation. Three months after completing chemotherapy, she had recurrent tumor in the left lobe of the liver and she died with progressive disease. The last patient whose parents were not suitable as donors for living-related liver transplantation is waiting for a deceased donor graft. All patients had limited disease to liver due to close clinical and radiological follow up for tyrosinemia. In these patients liver transplantation is curative both for liver tumor and tyrosinemia.     

Metabolic studies of transient tyrosinemia in premature infants.

The recently developed technique of gas chromatography-mass spectrometry supported by computer has considerably improved the analysis of physiologic fluids. This study attempted to demonstrate the value of this system in the investigation of metabolite patterns in urine in two metabolic problems of prematurity, transient tyrosinemia and late metabolic acidosis. Serial 24-hr urine specimens were analyzed in 9 infants. Transient tyrosinemia, characterized by 5-10-fold increases over basal excretion of tyrosine, p-hydroxyphenyllactate, and p-hydroxyphenylpyruvate in urine, was noted in five of the infants. Several infants had fluctuating levels of tyrosine metabolites in urine although dietary protein intake remained constant at 3-4 g/kg/24 hr and ascorbic acid at 50 mg/24 hr. Late metabolic acidosis was seen in four infants, but bore no relation to transient tyrosinemia. The ratio of net acid to urea excretion in urine increased with increasing base deficit, implying a nonprotein origin of the metabolic acid. No unique metabolic patterns were characteristic of late metabolic acidosis.     

Tyrosinemia type 1 in pediatric nephrology: Not always straightforward

The main clinical features of tyrosinemia type 1 usually appear in the first months of life, including fever, diarrhea, vomiting, liver involvement, growth failure, and renal proximal tubulopathy with subsequent hypophosphatemic rickets. An early diagnosis is crucial in order to provide specific management and to prevent complications. Here, we report on two cases referred primarily to pediatric nephrologists for the diagnosis of “neonatal tubulopathy” and management of “X-linked hypophosphatemia (XLH),” respectively. Our aim is to emphasize that (1) even a mixed tubulopathy can reveal tyrosinemia, and (2) tyrosinemia is a classic differential diagnosis of XLH that should not be forgotten, especially in the era of the anti-FGF23 burosumab.     

Tyrosinemia type 1 should be suspected in infants with severe coagulopathy even in the absence of other signs of liver failure

Tyrosinemia type l is an inherited metabolic disorder attributable to deficiency of fumarylacetoacetate hydrolase, a terminal enzyme in the degradation pathway of tyrosine. Affected individuals may present with any of a number of signs and symptoms, including failure to thrive, fever, vomiting, diarrhea, hepatomegaly, ascites, jaundice, renal Fanconi syndrome, or conditions such as rickets and hepatocellular carcinoma.1 If untreated, the patient may die of acute liver failure before the second year of life, or from chronic liver failure or hepatocellular carcinoma before the end of the second decade of life.2 Although overt liver failure with coagulopathy may be part of the presentation of tyrosinemia, a significant coagulopathy in the absence of overt signs of liver disease has not been emphasized as a clue to the diagnosis of this condition. We report two tyrosinemic infants who presented with severe coagulopathies and no other signs of liver failure to stress this diagnostic point.     

血尿琥珀酰丙酮检测在酪氨酸血症-Ⅰ型诊断中的应用

目的 探讨血、尿琥珀酰丙酮检测在酪氨酸血症-Ⅰ型诊断中的价值.方法 对临床疑似酪氨酸血症、血串联质谱检测酪氨酸水平增高的190例患儿,进行血串联质谱琥珀酰丙酮检测、尿气相色谱-质谱琥珀酰丙酮及有机酸检测.确诊条件为临床表现、血酪氨酸增高及血或尿琥珀酰丙酮增高.结果 确诊酪氨酸血症-Ⅰ型患儿11例,男9例,女2例,年龄2个月至6岁.患儿血琥珀酰丙酮显著升高( 14.2±7.8) μmol/L(参考值1～5μmol/L).其中7例患儿进行了尿气相色谱-质谱琥珀酰丙酮检测,4例阳性,3例阴性.血酪氨酸水平为(327.3±125.8) μmol/L(参考值为20 ～ 100μmol/L).临床表现均有肝肿大.结论 血或尿琥珀酰丙酮升高是诊断酪氨酸血症-Ⅰ型的最重要依据.串联质谱检测血琥珀酰丙酮较气相色谱-质谱检测尿琥珀酰丙酮对诊断酪氨酸血症-Ⅰ型更可靠,气相色谱-质谱尿琥珀酰丙酮检测可能导致假阴性.