Liver transplantation in tyrosinaemia type I: the Groningen experience

Decoding hepatorenal tyrosinemia type 1: Unraveling the impact of early detection, NTBC, and the role of liver transplantation

Hepatorenal tyrosinemia type 1 (HT-1) is a rare autosomal recessive disease that results from a deficiency of fumaryl acetoacetate hydrolase (FAH), a critical enzyme in the catabolic pathway for tyrosine. This leads to the accumulation of toxic metabolites such as fumaryl and maleylacetoacetate, which can damage the liver, kidneys, and nervous system. The discovery of 2-[2-nitro-4-trifluoromethylbenzoyl]-1,3-cyclohexanedione (NTBC or nitisinone) has significantly improved the management of HT-1, particularly when initiated before the onset of symptoms. Therefore, newborn screening for HT-1 is essential for timely diagnosis and prompt treatment. The analysis of succinyl acetone (SA) in dried blood spots of newborns followed by quantification of SA in blood or urine for high-risk neonates has excellent sensitivity and specificity for the diagnosis of HT-1. NTBC combined with dietary therapy, if initiated early, can provide liver transplant (LT) free survival and reduce the risk of hepatocellular carcinoma (HCC). Patients failing medical treatment (eg, due to non-adherence), and who develop acute liver failure (ALF), have HCC or evidence of histologically proven dysplastic liver nodule(s), or experience poor quality of life secondary to severe dietary restrictions are currently indicated for LT. Children with HT-1 require frequent monitoring of liver and renal function to assess disease progression and treatment compliance. They are also at risk of long-term neurocognitive impairment, which highlights the need for neurocognitive assessment and therapy.

Liver Transplantation: A Safe and Definitive Alternative to Lifelong Nitisinone for Tyrosinemia Type 1

OBJECTIVES

To report the experience of liver transplantation (LT) for tyrosinemia type 1 (TT-1).

METHODS

Clinical data of children with TT-1 who underwent living donor LT between July 2009 and May 2020 were retrospectively analyzed. Data included pre-LT nitisinone therapy, graft type, post-LT complications, HCC incidence, and graft/patient survival.

RESULTS

Nine children were diagnosed with TT-1 at a median age of 12 mo (6-54 mo). Nitisinone was started in 6 patients at a median age of 15 mo (6-42 mo), but all had frequent interruption of therapy due to logistics with drug procurement including its cost. Median age at transplantation was 5 y (2-11 y). Explant liver showed HCC in 5 patients (55% of total cohort). The graft and patient survival are 100% with median follow-up of 58 mo (24-84 mo).

CONCLUSION

LT is curative for TT-1 and excellent results can be obtained in experienced centers. This is especially favorable in countries with limited resources where the cost of medical therapy is highly prohibitive, with lifelong diet restrictions and unclear long-term risk of HCC.

Revisiting bupropion anti-inflammatory action: involvement of the TLR2/TLR4 and JAK2/STAT3

There are accumulating reports regarding poor response to common antidepressant therapy. Antidepressant resistance is often linked to inflammatory system activation and patients displaying inflammation prior to the treatment are less responsive to antidepressants. We hypothesized that the inefficacy of antidepressant therapy in some patients may be attributable to the drugs' inflammatory mode of action, which has been overlooked because of their substantial therapeutic benefit. Bupropion is a commonly prescribed antidepressant that is often used to treat seasonal affective disorders as well. Nevertheless, research suggests that bupropion causes inflammation and worsens depressive symptoms. Therefore, we investigated the impact of bupropion on cytokines of innate and adaptive immunity, as well as immune signaling pathways. We treated lipopolysaccharide (LPS)-stimulated human peripheral blood mononuclear cells (PBMCs) with different doses of bupropion. Pro-/anti-inflammatory cytokines [tumor necrosis factor alpha (TNFα), interleukin-1β (IL-1β), IL-17, and IL-10] were assessed at both transcriptional and translational levels as well as the involvement of JAK2 /STAT3, TLR2, and TLR4 signaling in this process. Bupropion reduced IL-17A, TNFα, and IL-1β protein levels in the cultures. Nonetheless, bupropion increased IL-1β (P < 0.0001), TNFα (P < 0.0001), and IL-17A (P < 0.05) mRNA levels. Treatment enhanced both IL-10 concentration (P < 0.0001) and gene expression (P < 0.0001). TLR2 (P < 0.0001), TLR4 (P < 0.0001), JAK2 (P < 0.0001), and STAT3 (P < 0.0001) gene expression also rose in response to bupropion. The findings imply that bupropion, particularly 50 μM and 100 μM, has pro-inflammatory effects and should be co-administered with anti-inflammatory medications, at least in patients with inflammatory conditions.

Long-Term Outcomes and Practical Considerations in the Pharmacological Management of Tyrosinemia Type 1

Tyrosinemia type 1 (TT1) is a rare metabolic disease caused by a defect in tyrosine catabolism. TT1 is clinically characterized by acute liver failure, development of hepatocellular carcinoma, renal and neurological problems, and consequently an extremely poor outcome. This review showed that the introduction of 2-(2-nitro-4-trifluoromethylbenzoyl)-1,3-cyclohexanedione (NTBC) in 1992 has revolutionized the outcome of TT1 patients, especially when started pre-clinically. If started early, NTBC can prevent liver failure, renal problems, and neurological attacks and decrease the risk for hepatocellular carcinoma. NTBC has been shown to be safe and well tolerated, although the long-term effectiveness of treatment with NTBC needs to be awaited. The high tyrosine concentrations caused by treatment with NTBC could result in ophthalmological and skin problems and requires life-long dietary restriction of tyrosine and its precursor phenylalanine, which could be strenuous to adhere to. In addition, neurocognitive problems have been reported since the introduction of NTBC, with hypothesized but as yet unproven pathophysiological mechanisms. Further research should be done to investigate the possible relationship between important clinical outcomes and blood concentrations of biochemical parameters such as phenylalanine, tyrosine, succinylacetone, and NTBC, and to develop clear guidelines for treatment and follow-up with reliable measurements. This all in order to ultimately improve the combined NTBC and dietary treatment and limit possible complications such as hepatocellular carcinoma development, neurocognitive problems, and impaired quality of life.

Impaired cognitive functioning in patients with tyrosinemia type I receiving nitisinone

OBJECTIVE

To examine cognitive functioning in patients with tyrosinemia type I treated with nitisinone and a protein-restricted diet.

STUDY DESIGN

We performed a cross-sectional study to establish cognitive functioning in children with tyrosinemia type I compared with their unaffected siblings. Intelligence was measured using age-appropriate Wechsler Scales. To assess cognitive development over time, we retrieved sequential IQ scores in a single-center subset of patients. We also evaluated whether plasma phenylalanine and tyrosine levels during treatment was correlated with cognitive development.

RESULTS

Average total IQ score in 10 patients with tyrosinemia type I receiving nitisinone was significantly lower compared with their unaffected siblings (71 ± 13 vs 91 ± 13; P = .008). Both verbal and performance IQ subscores differed (77 ± 14 vs 95 ± 11; P < .05 and 70 ± 11 vs 87 ± 15; P < .05, respectively). Repeated IQ measurements in a single-center subset of 5 patients revealed a decline in average IQ score over time, from 96 ± 15 to 69 ± 11 (P < .001). No significant association was found between IQ score and either plasma tyrosine or phenylalanine concentration.

CONCLUSION

Patients with tyrosinemia type I treated with nitisinone are at risk for impaired cognitive function despite a protein-restricted diet.

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.

[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.

Liver transplantation for hemochromatosis, Wilson's disease, and other metabolic disorders

Liver transplantation provides an effective means for replacing a failing liver, in addition to correcting the underlying abnormality in many metabolic disorders. Results of liver transplantation for metabolic diseases have been generally encouraging, with the exception of hereditary hemochromatosis, in which infectious and cardiac complications appear to increase post-transplant mortality. Better pretransplant diagnosis of hemochromatosis, utilizing the recently identified putative gene, may help reduce post-transplant complications. In metabolic diseases, improved understanding of the underlying genetic and molecular defects will lead to advances in medical therapy and perhaps a decreased need for liver transplantation. NTBC therapy for hereditary tyrosinemia and purified glucocerebroside therapy for Gaucher disease are two such examples. The prospects of gene therapy are being actively pursued for many metabolic diseases, such as CF, hemophilia, and familial hypercholesterolemia. Until such investigation leads directly to clinical practice, however, liver transplantation remains an effective option for therapy for a wide range of metabolic diseases.

Screening for tyrosinaemia type I

AIMS

To assess the incidence of tyrosinaemia type I in the West Midlands Region, and the value of current neonatal screening programmes for phenylketonuria (PKU) for its detection.

METHODS

Retrospective study of results from the PKU neonatal screening programmes in Birmingham (using plasma amino acid chromatography) and in the rest of the West Midlands (using the Guthrie microbiological assay for blood spot phenylalanine) was carried out between January 1985 and March 1994. Patients with tyrosinaemia I born in the region during the same period were identified from a regional database of patients with confirmed inherited metabolic disease. The study was carried out in a specialist children's hospital; the regional centre in the West Midlands for neonatal screening and investigation of inborn errors, and a supraregional centre for liver transplantation and management of paediatric liver disease.

RESULTS

Amino acid chromatography showed increased tyrosine in 447 of 145,444 neonates born in Birmingham; this was still increased at 6 weeks of age in six cases. Five had tyrosinaemia I; the sixth had tyrosinaemia type III. Two others in whom amino acid chromatography was considered normal have since presented with tyrosinaemia I. Outside Birmingham, 525,151 children were screened using the Guthrie test. Five have presented clinically with tyrosinaemia I; screening did not contribute to diagnosis in any case. The incidence of tyrosinaemia I was 1 in 20,791 live births within Birmingham and 1 in 105,037 outside. Of the total 12 patients in the West Midlands with tyrosinaemia I, 10 (83%) were of non-oriental Asian ethnicity; the incidence of tyrosinaemia I was 3.7/10(6) head of population in this group and 0.04/10(6) in the rest of the population.

CONCLUSIONS

Asians in the West Midlands have a high incidence of tyrosinaemia I. Neonatal PKU screening using amino acid chromatography may contribute to diagnosis and early treatment.