Tyrosinemia type I treated by NTBC: how does AFP predict liver cancer?

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.

Role of Alpha-Fetoprotein (AFP) in Diagnosing Childhood Cancers and Genetic-Related Chronic Diseases

Alpha-fetoprotein (AFP) is a protein commonly found during fetal development, but its role extends beyond birth. Throughout the first year of life, AFP levels can remain high, which can potentially mask various conditions from the neurological, metabolic, hematological, endocrine, and early childhood cancer groups. Although AFP reference values and clinical utility have been established in adults, evaluating AFP levels in children during the diagnostic process, treatment, and post-treatment surveillance is still associated with numerous diagnostic pitfalls. These challenges arise from the presence of physiologically elevated AFP levels, inconsistent data obtained from different laboratory tests, and the limited population of children with oncologic diseases that have been studied. To address these issues, it is essential to establish updated reference ranges for AFP in this specific age group. A population-based study involving a statistically representative group of patients could serve as a valuable solution for this purpose.

Using time-shared scanning optical tweezers assisted two-photon fluorescence imaging to establish a versatile CRISPR/Cas12a-mediated biosensor

Based on the admirable precision to identify target nucleic acids and the particular trans-cleavage feature, CRISPR/Cas12a system is a useful means to further improve the sensing accuracy and the design flexibility of fluorescence biosensors. However, the current construction concepts still suffer from insufficient sensitivity, unsuitable for complicated real samples and limited detection species. In this work, much efforts are achieved to address these obstacles. At first, we adopt a microsphere sustained signal enrichment, under which a home-made time-shared scanning optical tweezers assisted fluorescence imaging is employed to guarantee a stable excitation and also realize multiflux measurement. Furthermore, by taking advantage of the low background merit of the near-infrared light excited two-photon fluorescence, a commendable anti-interference capability is endowed to operate in complex media. After utilizing a functional DNA (e.g. aptamer and DNAzyme) regulated mediation pathway to respond non-nucleic acid analytes (alpha fetal protein and Pb²⁺), the newly-established CRISPR/Cas12a-mediated fluorescence biosensor is found to display favorable assay performance. More importantly, our analytical methodology can act as a versatile and reliable toolbox in various applications such as disease diagnosis and environmental analysis, propelling the development of CRISPR system in biosensing field.

In vivo quantitative photoacoustic evaluation of the liver and kidney pathology in tyrosinemia

Hereditary tyrosinemia type Ⅰ (HT1) is a severe autosomal recessive inherited metabolic disease, which can result in severe damage of liver and kidney. Photoacoustic imaging (PAI) uses pulsed laser light to induce ultrasonic signals to facilitate the visualization of lesions that are strongly related to disease progression. In this study, the structural and functional changes of liver and kidney in HT1 was investigated by cross-scale PAI. The results showed that the hepatic lobule and renal tubule were severely damaged during HT1 progression. The hemoglobin content, vessel density, and liver function reserve were decreased. The metabolic half-life of indocyanine green declined from 59.8 s in health to 262.6 s in the advanced stage. Blood oxygen saturation was much lower than that in health. This study highlights the potential of PAI for in vivo evaluation of the liver and kidney lesions in HT1.

Hepatocellular carcinoma requiring liver transplantation in hereditary tyrosinemia type 1 despite nitisinone therapy and α1-fetoprotein normalization

BACKGROUND

Hereditary tyrosinemia type 1 is a rare metabolic condition associated with an increased risk of hepatocellular carcinoma. Nitisinone (2-[2-nitro-4-trifluoromethylbenzoyl]-1,3-cyclohexanedione, NTBC) treatment has reduced but not eliminated the risk. The delayed initiation of nitisinone treatment, and persistently abnormal α1-fetoprotein (AFP) levels are recognized to be risk factors for late-onset hepatocellular carcinoma. We report three children diagnosed and treated with nitisinone since infancy who developed hepatocellular carcinoma despite long-term normalization of AFP.

METHODS

A retrospective review of all patients with tyrosinemia on nitisinone managed at our center was undertaken. Patient demographics, age at diagnosis, duration of therapy, timing of AFP normalization, and radiographic imaging findings were noted.

RESULTS

Three patients at our center with tyrosinemia type 1 developed hepatocellular carcinoma 9-13 years after diagnosis despite long-term nitisinone therapy and normalization of AFP. Two patients developed new nodules on imaging with an elevation of AFP leading to the diagnosis and subsequent liver transplant. The third patient proceeded with liver transplant because of a very nodular liver and increasing splenomegaly despite normal AFP and no change in surveillance gadoxetate magnetic resonance imaging. Early hepatocellular carcinoma was found in her liver explant. All three patients were cirrhotic at diagnosis.

CONCLUSIONS

Patients with hereditary tyrosinemia type 1, especially those already cirrhotic at diagnosis, remain at high risk of developing hepatocellular carcinoma despite long-term nitisinone therapy and AFP normalization, and warrant close monitoring and surveillance.

In vivo lentiviral vector gene therapy to cure hereditary tyrosinemia type 1 and prevent development of precancerous and cancerous lesions

Conventional therapy for hereditary tyrosinemia type-1 (HT1) with 2-(2-nitro-4-trifluoromethylbenzoyl)−1,3-cyclohexanedione (NTBC) delays and in some cases fails to prevent disease progression to liver fibrosis, liver failure, and activation of tumorigenic pathways. Here we demonstrate cure of HT1 by direct, in vivo administration of a therapeutic lentiviral vector targeting the expression of a human fumarylacetoacetate hydrolase (FAH) transgene in the porcine model of HT1. This therapy is well tolerated and provides stable long-term expression of FAH in pigs with HT1. Genomic integration displays a benign profile, with subsequent fibrosis and tumorigenicity gene expression patterns similar to wild-type animals as compared to NTBC-treated or diseased untreated animals. Indeed, the phenotypic and genomic data following in vivo lentiviral vector administration demonstrate comparative superiority over other therapies including ex vivo cell therapy and therefore support clinical application of this approach.

Hereditary tyrosinemia type 1 (HT1) is an inborn error of metabolism caused by a deficiency in fumarylacetoacetate hydrolase (FAH). Here, the authors show in an animal model that HT1 can be treated via in vivo portal vein administration of a lentiviral vector carrying the human FAH transgene.

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.

NTBC Treatment Monitoring in Chilean Patients with Tyrosinemia Type 1 and Its Association with Biochemical Parameters and Liver Biomarkers

Treatment and follow-up in Hereditary Tyrosinemia type 1 (HT-1) patients require comprehensive clinical and dietary management, which involves drug therapy with NTBC and the laboratory monitoring of parameters, including NTBC levels, succinylacetone (SA), amino acids, and various biomarkers of liver and kidney function. Good adherence to treatment and optimal adjustment of the NTBC dose, according to clinical manifestations and laboratory parameters, can prevent severe liver complications such as hepatocarcinogenesis (HCC). We analyzed several laboratory parameters for 15 HT-1 patients over one year of follow-up in a cohort that included long-term NTBC-treated patients (more than 20 years), as well as short-term patients (one year). Based on this analysis, we described the overall adherence by our cohort of 70% adherence to drug and dietary treatment. A positive correlation was found between blood and plasma NTBC concentration with a conversion factor of 2.57. Nonetheless, there was no correlation of the NTBC level with SA levels, αFP, liver biomarkers, and amino acids in paired samples analysis. By separating according to the range of the NTBC concentration, we therefore determined the mean concentration of each biochemical marker, for NTBC ranges above 15–25 μmol/L. SA in urine and αFP showed mean levels within controlled parameters in our group of patients. Future studies analyzing a longer follow-up period, as well as SA determination in the blood, are encouraged to confirm the present findings.

Type 1 tyrosinemia in Finland: a nationwide study

Background

Introduction of nitisinone and newborn screening (NBS) have transformed the treatment of type 1 tyrosinemia, but the effects of these changes on the long-term outcomes remain obscure. Also, the predictors for later complications, the significance of drug levels and the normalization of laboratory and imaging findings are poorly known. We investigated these issues in a nationwide study.

Results

Type 1 tyrosinemia was diagnosed in 22 children in 1978–2019 in Finland. Incidence was 1/90,102, with a significant enrichment in South Ostrobothnia (1/9990). Median age at diagnosis was 5 (range 0.5–36) months, 55% were girls and 13 had homozygotic Trp262X mutation. Four patients were detected through screening and 18 clinically, their main findings being liver failure (50% vs. 100%, respectively, p = 0.026), ascites (0% vs. 53%, p = 0.104), renal tubulopathy (0% vs. 65%, p = 0.035), rickets (25% vs. 65%, p = 0.272), growth failure (0% vs. 66%, p = 0.029), thrombocytopenia (25% vs. 88%, p = 0.028) and anaemia (0% vs. 47%, p = 0.131). One patient was treated with diet, seven with transplantation and 14 with nitisinone. Three late-diagnosed (6–33 months) nitisinone treated patients needed transplantation later. Kidney dysfunction (86% vs. 7%, p = 0.001), hypertension (57% vs. 7%, p = 0.025) and osteopenia/osteoporosis (71% vs. 14%, p = 0.017) were more frequent in transplanted than nitisinone-treated patients. Blood/serum alpha-fetoprotein decreased rapidly on nitisinone in all but one patient, who later developed intrahepatic hepatocellular carcinoma. Liver values normalized in 31 months and other laboratory values except thrombocytopenia within 18 months. Imaging findings normalized in 3–56 months excluding five patients with liver or splenic abnormalities. Low mean nitisinone concentration was associated with higher risk of severe complications (r = 0.758, p = 0.003) despite undetectable urine succinylacetone.

Conclusions

Prognosis of type 1 tyrosinemia has improved in the era of nitisinone, and NBS seems to provide further benefits. Nevertheless, the long-term risk for complications remains, particularly in the case of late diagnosis and/or insufficient nitisinone levels.

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.

Daily variation of NTBC and its relation to succinylacetone in tyrosinemia type 1 patients comparing a single dose to two doses a day

INTRODUCTION

In hereditary tyrosinemia type 1 (HT1) patients, the dose of NTBC that leads to the absence of toxic metabolites such as succinylacetone (SA) is still unknown. Therefore, the aims of this study were to investigate the variation and concentrations of 2-(2-nitro-4-trifluormethyl-benzyl)-1,3-cyclohexanedione (NTBC) during the day in relation to the detection of SA, while comparing different dosing regimens.

METHODS

All patients were treated with NTBC (mean 1.08 ± 0.34 mg/kg/day) and a low phenylalanine-tyrosine diet. Thirteen patients received a single dose of NTBC and five patients twice daily. Home bloodspots were collected four times daily for three consecutive days measuring NTBC and SA concentrations. Statistical analyses were performed by using mixed model analyses and generalized linear mixed model analyses to study variation and differences in NTBC concentrations and the correlation with SA, respectively.

RESULTS

NTBC concentrations varied significantly during the day especially if NTBC was taken at breakfast only (p = 0.026), although no significant difference in NTBC concentrations between different dosing regimens could be found (p = 0.289). Momentary NTBC concentrations were negatively correlated with SA (p < 0.001). Quantitatively detectable SA was only found in subjects with once daily administration of NTBC and associated with momentary NTBC concentrations <44.3 μmol/l.

DISCUSSION

NTBC could be less stable than previously considered, thus dosing NTBC once daily and lower concentrations may be less adequate. Further research including more data is necessary to establish the optimal dosing of NTBC.

Liver Cancer in Tyrosinemia Type 1

Hereditary Tyrosinemia type I (HT1) is clinically mainly characterised by severe liver disease. Most patients present in their first months of life with liver failure, but others can present later with issues of compensated cirrhosis, renal tubulopathy or acute intermittent porphyria. If patients survive the acute phase with liver failure or if they present later with compensated cirrhosis, they often develop hepatocellular carcinoma early but also later in life. The course of the disease changed after the introduction of 2-(2 nitro-4-3 trifluoro-methylbenzoyl)-1, 3-cyclohexanedione (NTBC), which blocks the tyrosine degradation pathway at an earlier step. Therefore, the toxic products did not accumulate anymore and all clinical problems resolved. However, the risk (although clearly decreased) for developing liver cancer remained, especially if NTBC treatment is initiated late, a slow decrease of the tumor marker α-fetoprotein is seen or if the α-fetoprotein concentrations remain just above the normal range. A rise of α-fetoprotein in these HT1 patients is more or less pathognomonic for liver cancer. Although hepatoblastoma development occurs in HT1 patients, most HT1 patients develop hepatocellular carcinoma (HCC) or a mixed type of carcinoma consisting of HCC and hepatoblastoma. Due to the small risk of liver cancer development, screening for liver cancer (especially HCC) is still recommended in HT1 patients using regular measures of α-fetoprotein and imaging. Ultrasound is mostly the modality of choice for surveillance, because it is widely available, it does not use radiation and is noninvasive. When a suspicious lesion is present, the higher sensitivity of MRI could be used for characterization and staging of lesions. At this moment, no HCC development in pre-symptomatically treated patients is reported. These different situations could possibly indicate that NTBC can prevent the start of the development of HCC when initiated early, but can't stop the development of HCC if it is prescribed at a later stage, stressing the importance of early diagnosis.

The Liver in Tyrosinemia Type I: Clinical Management and Course in Quebec

HT1 is a severe autosomal recessive disorder due to the deficiency of fumarylacetoacetate hydrolase (FAH), the final enzyme in the degradation of tyrosine. Before the era of treatment with 2-(2-N-4-trifluoromethylbenzoyl)-1,3-cyclohexanedione (NTBC), even with newborn screening and optimal diet therapy, HT1 patients often developed liver failure. Death was common in patients who did not undergo liver transplantation. For the last two decades, NTBC has revolutionized the management of HT1 patients. In screened newborns treated within the first month of life, we have not observed hepatocarcinoma. If patients are not detected at birth by neonatal screening, the diagnosis and treatment must be performed on an emergency basis, and patients are at risk for complications. Long term adhesion to treatment and reliable early detection of hepatocellular carcinoma (HCC) are two important challenges. In this chapter, we describe the clinical, biological, histo-pathological and imaging findings of HT1 in Québec before the era of NTBC. We also describe the hepatic status of nontransplanted tyrosinemic patients in Quebec and current management practices in the Quebec NTBC Study.

The outcome of seven patients with hereditary tyrosinemia type 1

BACKGROUND

Hereditary tyrosinemia type 1 (HT1) is a rare, inborn error of tyrosine metabolism. It is a fatal disorder without treatment. Early treatment may prevent acute liver failure, renal dysfunction, liver cirrhosis, hepatocellular carcinoma (HCC) and improves survival. The aim of the present study is to describe the clinical, biochemical, imaging and follow-up of seven patients with HT1 and to define the consequences of the late and interrupted treatment.

METHODS

A retrospective study was carried out with seven HT1 patients.

RESULTS

The median age at onset of clinical symptoms was 11.2 months (range, 3-28 months) and the median age at diagnosis was 22 months (range, 6-58 months). Liver enzymes and coagulation parameters were back to normal in all symptomatic patients in about 2 weeks. Alfa-fetoprotein (AFP) levels were normalized within the first year of therapy. Hypoechoic nodule formation was detected in two of the seven patients despite drug treatment without an increase of AFP and any dysplastic changes in the biopsies. One patient died due to metastatic HCC because of the late diagnosis and the poor compliance of the follow-up.

CONCLUSIONS

This study showed once again that adherence to the treatment and a follow-up schedule of the patients are very important. Also it should not be forgotten that nodule formation can occur despite nitisinone treatment without an increase of AFP. Despite nitisinone treatment, HT1 patients still carry the risk of HCC. HCC must be detected before metastasis to other organs otherwise, patients may lose the chance for liver transplantation.

Liver tumors in children with metabolic disorders

Hepatic neoplasia is a rare but serious complication of metabolic diseases in children. The risk of developing neoplasia, the age at onset, and the measures to prevent it differ in the various diseases. We review the most common metabolic disorders that are associated with a heightened risk of developing hepatocellular neoplasms, with a special emphasis on reviewing recent advances in the molecular pathogenesis of the disorders and pre-clinical therapeutic options. The cellular and genetic pathways driving carcinogenesis are poorly understood, but best understood in tyrosinemia.

Hereditary tyrosinemia type 1 in Turkey: twenty year single-center experience

BACKGROUND

Hereditary tyrosinemia type 1(HT1) is a chronic disorder leading to severe hepatic, renal and peripheral nerve damage if left untreated. Despite nitisinone treatment HT1 still carries the risks of hepatocellular carcinoma (HCC) and neuropsychological outcome.

METHODS

A retrospective single center study was carried out based on the phenotype, therapy and outcome in 38 Turkish patients with HT1 diagnosed during the last 20 years.

RESULTS

None of the patients was diagnosed on newborn screening. The patients were grouped according to acute, subacute and chronic forms of the disorder. The main clinical manifestations were hepatosplenomegaly, liver and renal tubular dysfunction. Thirty-six patients were treated with nitisinone. The mean duration of nitisinone treatment was 64 months and the mean dosage was 1.2 mg/kg/day. Dietary compliance problems were frequent. Eleven patients had cognitive evaluation (mean total IQ, 84 points). Six patients had living donor liver transplantation despite nitisinone treatment: three due to suspected HCC, two for non-compliance to diet, and one for both, at a median age of 90 months.

CONCLUSION

Nitisinone treatment is effective and improves both short- and long-term prognosis of HT1. Early diagnosis on newborn screening is needed because delay in treatment increases the risk of the persistence of hepatic disease and HCC. Interruption of the drug can lead to re-occurrence of hepatocellular damage and neurological crisis. Increased α-fetoprotein and new hypoechoic nodule formation are the warning signs for HCC.

HCC prevalence and histopathological findings in liver explants of patients with hereditary tyrosinemia type 1

BACKGROUND

Untreated tyrosinemia type 1 (HT1) is manifested by liver failure associated with renal tubular dysfunction, growth failure, and rickets. The indication for liver transplantation (LT) is restricted to non-responders to 2-(2-nitro-4-trifluoromethylbenzoyl)-1, 3-cyclohexanedione (NTBC) treatment, patients not treated with NTBC or for patients with HCC. The aim of this study is to report on a series of NTBC naive HT1 patients submitted to LT along with the prevalence of HCC in their liver explants.

PROCEDURE

This is a retrospective study of 16 children with HT1 who underwent liver transplantation between January 1993 and December 2012.

CLINICAL FEATURES

liver failure in 12 (75%), growth failure in 4 (25%), rickets in 5 (31.2%), hypertrophic cardiomyopathy in three (18.7%), and renal tubulopathy in seven patients (43.7%). Median AFP level was 64,335 ng/ml. Abdominal CT scans showed multiple nodules in most patients. Histopathology of the explants showed cirrhosis in all patients and HCC in 12 (75%), 3 with microvascular invasion. The majority of the tumors were well differentiated. Patient survival rate was 86% at a median follow-up of 6.6 years. All survivors were tumor-free with no adjuvant chemotherapy.

CONCLUSION

In countries where neonatal screening programs are not effective and NTBC treatment is not widely available, LT still plays an important role in the treatment of children with HT1. An early indication in patients who present with multinodular livers can also serve to treat an otherwise underdiagnosed HCC condition.

Cross-sectional study of 168 patients with hepatorenal tyrosinaemia and implications for clinical practice

BACKGROUND

Hepatorenal tyrosinaemia (Tyr 1) is a rare inborn error of tyrosine metabolism. Without treatment, patients are at high risk of developing acute liver failure, renal dysfunction and in the long run hepatocellular carcinoma. The aim of our study was to collect cross-sectional data.

METHODS

Via questionnaires we collected retrospective data of 168 patients with Tyr 1 from 21 centres (Europe, Turkey and Israel) about diagnosis, treatment, monitoring and outcome. In a subsequent consensus workshop, we discussed data and clinical implications.

RESULTS

Early treatment by NTBC accompanied by diet is essential to prevent serious complications such as liver failure, hepatocellular carcinoma and renal disease. As patients may remain initially asymptomatic or develop uncharacteristic clinical symptoms in the first months of life newborn mass screening using succinylacetone (SA) as a screening parameter in dried blood is mandatory for early diagnosis. NTBC-treatment has to be combined with natural protein restriction supplemented with essential amino acids. NTBC dosage should be reduced to the minimal dose allowing metabolic control, once daily dosing may be an option in older children and adults in order to increase compliance. Metabolic control is judged by SA (below detection limit) in dried blood or urine, plasma tyrosine (<400 μM) and NTBC-levels in the therapeutic range (20-40 μM). Side effects of NTBC are mild and often transient. Indications for liver transplantation are hepatocellular carcinoma or failure to respond to NTBC. Follow-up procedures should include liver and kidney function tests, tumor markers and imaging, ophthalmological examination, blood count, psychomotor and intelligence testing as well as therapeutic monitoring (SA, tyrosine, NTBC in blood).

CONCLUSION

Based on the data from 21 centres treating 168 patients we were able to characterize current practice and clinical experience in Tyr 1. This information could form the basis for clinical practice recommendations, however further prospective data are required to underpin some of the recommendations.

Liver Transplant for Children With Hepatocellular Carcinoma and Hereditary Tyrosinemia Type 1

OBJECTIVES

This study sought to determine the prevalence of hepatocellular carcinoma and other premalignant lesions in children with hereditary tyrosinemia type 1 who had undergone an orthotopic liver transplant at the Shiraz Transplant Center, in Shiraz, Iran.

MATERIALS AND METHODS

Between September 2006, and June 2011, thirty-six patients with hereditary tyrosinemia type 1 received a liver transplant from a deceased (whole or split) or a living-related donor. Clinical records and pathologic specimens, before and after surgery, for each case were reviewed. In addition, ultrasound, abdominal computed tomographic imaging scan findings, and levels of alpha-fetoprotein were recorded.

RESULTS

Twenty-two patients with hepatic nodules larger than 10 mm underwent a Tru-Cut needle biopsy before their liver transplant. In 2 patients, a diagnosis of hepatocellular carcinoma was made by pathologic examination; in the other 20, cirrhosis was confirmed with no evidence of malignancy. After pathologic examination of the explanted livers, the largest nodules in the 36 patients were 35 mm. Five cases had at least 1 nodule of hepatocellular carcinoma. Three of the other patients had small cell dysplasia in some of nodules. All 5 cases with hepatocellular carcinoma were patients older than 2 years of age (19 patients were older than 2 years of age). All patients with hepatocellular carcinoma received pretransplant nitisinone treatment. All patients with hepatocellular carcinoma after their liver transplant are alive at the time of this writing.

CONCLUSIONS

The prevalence of cell dysplasia and hepatocellular carcinoma in children with hereditary tyrosinemia type 1 in our study is not as high as that reported previously, so it appears that patients older than 2 years of age require a liver transplant.

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.

Analytical Study of Performance of Linear Discriminant Analysis in Stochastic Settings

This paper provides exact analytical expressions for the first and second moments of the true error for linear discriminant analysis (LDA) when the data are univariate and taken from two stochastic Gaussian processes. The key point is that we assume a general setting in which the sample data from each class do not need to be identically distributed or independent within or between classes. We compare the true errors of designed classifiers under the typical i.i.d. model and when the data are correlated, providing exact expressions and demonstrating that, depending on the covariance structure, correlated data can result in classifiers with either greater error or less error than when training with uncorrelated data. The general theory is applied to autoregressive and moving-average models of the first order, and it is demonstrated using real genomic data.

Recommendations for the management of tyrosinaemia type 1

The management of tyrosinaemia type 1 (HT1, fumarylacetoacetase deficiency) has been revolutionised by the introduction of nitisinone but dietary treatment remains essential and the management is not easy. In this review detailed recommendations for the management are made based on expert opinion, published case reports and investigational studies as the evidence base is limited and there are no prospective controlled studies.

The added value of this paper is that it summarises in detail current clinical knowledge about HT1 and makes recommendations for the management.

Recommendations for the management of tyrosinaemia type 1

The management of tyrosinaemia type 1 (HT1, fumarylacetoacetase deficiency) has been revolutionised by the introduction of nitisinone but dietary treatment remains essential and the management is not easy. In this review detailed recommendations for the management are made based on expert opinion, published case reports and investigational studies as the evidence base is limited and there are no prospective controlled studies.The added value of this paper is that it summarises in detail current clinical knowledge about HT1 and makes recommendations for the management.

Heterogeneity of follow-up procedures in French and Belgian patients with treated hereditary tyrosinemia type 1: results of a questionnaire and proposed guidelines

The 1991 introduction of 2-(2-nitro-4-trifluoro-methylbenzyol)-1,3 cyclohexanedione (NTBC) as a treatment for hereditary tyrosinemia type 1 (HT-1), a disorder of tyrosine catabolism, has radically modified the natural history of this disorder. Despite the dramatic improvements in survival, outcomes and quality of life seen with NTBC treatment, HT-1 remains a chronic disorder with several long-term complications, including, a persistent (albeit low) risk of hepatocellular carcinoma and suboptimal neuropsychological outcomes. There remain unsolved key-questions concerning the long-term outcomes of patients with HT-1, which closely depend on the quality of follow-up in these patients. In the absence of published guidelines, we investigated the follow-up methods used for French and Belgian patients with HT-1. A simple questionnaire providing a rapid overview of follow-up procedures was sent to the 19 physicians in charge of HT-1 patients treated with NTBC and low-tyrosine diet in France and Belgium. Several areas of heterogeneity (especially liver imaging, slit lamp examination, neuropsychological evaluation and maximal plasma tyrosine level accepted) were observed. In an attempt to improve long-term management and outcome of patients with HT-1, we proposed follow-up recommendations.

Tyrosinemia type 1 in Spain: mutational analysis, treatment and long-term outcome

BACKGROUND

Tyrosinemia type 1 (HT1) is a rare but treatable disease. The aim of the present study was to review the efficacy of long-term treatment of HT1 with nitisinone, expand knowledge about the clinical spectrum of the disease and assess a possible genotype-phenotype correlation.

METHODS

A retrospective multicenter study was carried out based on questionnaires on genotype, phenotype, therapy and outcome in 34 Spanish patients with HT1.

RESULTS

The main manifestations that led to the diagnosis were acute liver failure (55.8%), asymptomatic hepatomegaly (44.1%) and renal tubular dysfunction (29.4%). Laboratory analysis indicated a marked increase of α-fetoprotein and coagulopathy. The most common mutation was IVS6-1(G > T; 66.6% of 24/34 patients for whom mutation analysis was available) and these patients presented less nephrocalcinosis and more hepatomegaly at diagnosis; two novel mutations (c.974C>T, c.398A>T) were found. The mean duration of treatment was 6.73 years. Dietary compliance was very good in 47.1% and good in 20.6%; nitisinone treatment adherence was very good in 85.2% of cases. Mean dose of nitisinone was 0.87 mg/kg per day with average plasma levels of 45.67 µmol/L. Only one patient required liver transplantation after nitisinone and none had hepatocellular carcinoma.

CONCLUSIONS

Treatment with nitisinone has improved the prognosis of HT1, and compliance is good. In Spain, screening for HT1 by plasma tyrosine and urine succinylacetone determination may be implemented with IVS6-1(G > T) mutational analysis. A correlation between low frequency of nephrocalcinosis and IVS6-1(G > T) mutation was observed.

Hepatic neoplasia and metabolic diseases in children

Hepatic neoplasia is a rare but serious complication of metabolic diseases in children. The risk of developing neoplasia, the age at onset, and the measures to prevent it differ in various diseases. This article reviews the most common metabolic disorders in humans that are associated with neoplasms, with a special emphasis on the molecular etiopathogenesis of this process. The cellular pathways driving carcinogenesis are poorly understood, but best known in tyrosinemia.

[Recommendations and management of type I hereditary or hepatorenal tyrosinemia]

Tyrosinemia type I is a potentially lethal disease if not diagnosed and treated properly. Diagnostic and therapeutic advances in recent years have significantly improved the prognosis for these patients. It is therefore important that the pediatrician has a clinical practice guideline with recommendations for diagnosis and treatment of this disease that leads to the appropriate intervention.

Tyrosinemia type 1: metastatic hepatoblastoma with a favorable outcome

The clinical course of tyrosinemia type 1 is characterized by acute liver failure in infancy or chronic liver dysfunction and renal Fanconi syndrome in late-presenting cases. Dietary treatment may improve liver function but does not prevent the development of hepatocellular carcinoma (HCC) in late childhood. A new treatment strategy that uses 2-(2-nitro-4-trifluoromethylbenzoyl)-1,3-cyclohexanedione (NTBC), which prevents the production of toxic/carcinogenic metabolites, has dramatically changed the outcome of the disease by reducing the occurrence of liver cancer, especially in patients who start this treatment before the age of 2 years. We report here the case of a patient with a diagnosis of tyrosinemia type 1 at 5 months of age who was treated with NTBC and dietary restriction and in whom a liver neoplasm with lung metastases, histologically determined to be HCC, was found at the age of 15 months. A conservative approach that consisted of chemotherapy and partial hepatectomy resulted in a 12-year disease-free period. The excellent postchemotherapy course, in sharp contrast to the expected course of HCC, led to histologic reevaluation with reclassification of the neoplasm as hepatoblastoma. A diagnosis of hepatoblastoma would no longer be a mandate for a liver transplant for patients with tyrosinemia type 1 undergoing NTBC treatment. We encourage clinicians to perform more accurate evaluation of liver histology, because a neoplastic mass in a child with tyrosinemia type 1 is not the same as HCC.

AFP computational secreted network construction and analysis between human hepatocellular carcinoma (HCC) and no-tumor hepatitis/cirrhotic liver tissues

Alpha-fetoprotein (AFP) computational secreted network construction and analysis of human hepatocellular carcinoma (HCC) is very useful to identify novel markers and potential targets for prognosis and therapy. By integration of gene regulatory network infer and the database for annotation, visualization, and integrated discovery, we identified and constructed significant molecule AFP secreted network from 25 no-tumor hepatitis/cirrhotic liver tissues and 25 HCC patients in the same GEO Dataset GSE10140-10141. Our result verified AFP secreted module in the upstream of no-tumor hepatitis/cirrhotic liver tissues (AMELY, LCN2, and REG3A activation; DKK1, SFRP4, and SPINK1 inhibition) and its downstream (PRSS1, REG3A, and TSHB activation; AMELY and DKK1 inhibition), and also in the upstream of HCC (LCN2, REG3A, and SFRP4 activation; AMELY and DKK1 inhibition) and its downstream (AMELY activation; DKK1, LCN2, PRSS1, SEMA3B, and SPINK1 inhibition). Importantly, we data-mined that AFP secreted cluster of HCC is involved in disease mutation (only in HCC terms) without cell surface receptor linked signal transduction, neuroactive ligand-receptor interaction, cell-cell signaling, and pancreas (only in no-tumor hepatitis/cirrhotic liver tissues terms), the condition which is vital to invasion of HCC. Our result demonstrated that common terms in both no-tumor hepatitis/cirrhotic liver tissues and HCC include secreted extracellular region, extracellular region part, extracellular space, signal peptide, signal, disulfide bond, glycosylation site N-linked (GlcNAc...), and glycoprotein, and these terms are less relative to invasion; therefore, we deduced the weaker AFP secreted network in HCC consistent with our number computation. We predicted AFP high expression localization within cells of HCC and without secretion to extracellular matrix. It would be necessary of AFP secreted function to decrease invasion of HCC.

Significant increase of succinylacetone within the first 12 h of life in hereditary tyrosinemia type 1

INTRODUCTION

In most countries, hereditary tyrosinemia type 1 is not included in routine newborn screening.

DISCUSSION

We present the case of a female newborn with prenatal diagnosis of hereditary tyrosinemia type 1 and clear identification of this disorder by succinylacetone measurement in cord blood and peripheral blood immediately after birth. Succinylacetone was 44 micromol/L (norm <5 micromol/L) and increased within 12 h to 87.5 micromol/L.

CONCLUSION

With the high toxic potential of downstream metabolites, these data clearly point out the necessity of early nitisinone treatment to prevent symptomatic disease.

Severe neurological crisis in a patient with hereditary tyrosinaemia type I after interruption of NTBC treatment

Neurological crises do not occur in patients with tyrosinaemia type I treated with NTBC. We report an 8 month-old boy with severe neurological crisis after interruption of NTBC treatment including progressive ascending polyneuropathy and diaphragmatic paralysis, arterial hypertension, respiratory distress requiring mechanical ventilation who later also developed impaired liver function and tubulopathy. After re-introduction of NTBC the patient slowly regained normal neurological functions and recovered completely.

Rescue from neonatal death in the murine model of hereditary tyrosinemia by glutathione monoethylester and vitamin C treatment

Hereditary tyrosinemia type 1 (HT1) is a recessive disease caused by a deficiency of the enzyme fumarylacetoacetate hydrolase (FAH) that catalyzes the conversion of fumarylacetoacetate (FAA) into fumarate and acetoacetate. In mice models of HT1, FAH deficiency causes death within the first 24h after birth. Administration of 2-(2-nitro-4-trifluoro-methylbenzoyl)-1,3 cyclohexanedione (NTBC) prevents neonatal death in HT1 mice, ameliorates the HT1 phenotype but does not prevent development of hepatocellular carcinoma later on. FAA has been shown to deplete cells of glutathione by forming adducts. We tested whether a combination of a cell membrane permeable derivative of glutathione, glutathione monoethylester (GSH-MEE) and vitamin C could provide an alternative effective treatment for HT1. GSH-MEE (10 mmol/kg/j)/vitamin C (0.5 mmol/kg/j) treatment was given orally to pregnant/nursing female mice. While FAH-/- pups died in absence of treatment, all FAH-/- pups survived the critical first 24h of life when the mothers were on the GSH-MEE/vitamin C treatment and showed normal growth until postnatal day 10 (P10). However, after P10, pups showed failure to thrive, lethargy and died around P17. Thus, GSH-MEE/vitamin C supplementation could rescue the mice model of HT1 from neonatal death but it did not prevent the appearance of a HT1 phenotype in the second week after birth.