Evaluation of living donors for hereditary liver disease (siblings, heterozygotes)

Urea cycle defects in adulthood: clinical presentation, diagnosis and treatment in genetically encoded hepatic metabolic disorders with a potential for encephalopathy

Hyperammonaemia is an important cause for encephalopathy. Ammonia is the waste product of amino acid degradation and cannot be excreted via urine. Ammonia is metabolized to water-soluble urea via the urea cycle. Hyperammonaemia not only occurs during acute liver failure, but also in rare genetically determined defects of enzymes or transporters involved in the urea cycle resulting in elevated ammonia concentrations. Enzyme defects include deficiency of carbamylphosphate synthase, N-acetylglutamate synthase, ornithine transcarbamylase, argininosuccinate lyase and arginase, transporter defects are citrin deficiency and HHH-syndrome. These urea cycle defects (UCD) mostly manifest for the first time during the neonatal period, infancy or childhood, however first clinical manifestations including encephalopathy may be observed in adulthood in milder forms. Therefore, physicians treating adults should be aware of clinical symptoms in UCD to make a timely diagnosis and initiate treatment. In adulthood, clinical symptoms are often uncharacteristic including headache, avoidance of high-protein food, psychiatric symptoms triggered by heavy exercise or delivery of a child, autism, attention deficit, lethargy, developmental delay and epilepsy. Elevated ammonia concentrations in blood are the biochemical hallmark. Some UCDs can be diagnosed at metabolite level, others only at genetic level. Treatment consists of eucaloric, low-protein diet supplemented with essential amino acids and vitamins/trace elements, and intake of arginine or citrulline. Pharmacological scavengers of nitrogen are benzoate and butyrate. If conservative therapy fails, hemodialysis should be considered. Prompt treatment during acute crises is essential for optimal outcome. Liver transplantation is considered in metabolically unstable patients. For arginase deficiency, enzyme replacement therapy is available.

Progress of pediatric liver transplantation: In Japan and beyond

ABSTRACT

Organ transplantation, particularly pediatric liver transplantation (LT), has transformed medical practice over the past six decades, providing life-saving interventions for children with end-stage liver disease. This review demonstrated the historical milestones of pediatric organ transplantation, emphasizing Japan's contributions, mainly through the National Center for Child Health and Development. While early transplantation efforts in the 1950s and 1960s faced significant challenges, breakthroughs in preservation methods, immunosuppressive therapies, surgical techniques, and innovations such as living donor LT in Asia have greatly improved success rates. Japan's pediatric LT landscape is distinct, primarily due to its reliance on living donor LT, shaped by cultural and religious influences that have traditionally restricted deceased donor organ donation. This review manuscript discusses Japan's pioneering role in expanding the indications for pediatric LT to include rare conditions such as inherited metabolic disorders and hepatoblastoma. It highlights recent innovations such as hyper-reduced lateral segment grafts, machine perfusion, and minimally invasive surgery that have further improved outcomes. International collaboration has facilitated the sharing of expertise, advancing pediatric liver transplantation practice worldwide. Despite these achievements, challenges remain, particularly in light of Japan's declining birth rate, which threatens the sustainability of pediatric transplant services. This review emphasizes the need for centralized transplant facilities, greater awareness of brain-dead organ donation, and continued medical advances to ensure that pediatric LT remains a viable, life-saving option for future generations.

The Impact of Early Indication of Living Donor Liver Transplantation on the Outcomes of Patients With Propionic Acidemia: A Single-Center Experience

BACKGROUND

Liver transplantation has been indicated for propionic acidemia (PA) patients with frequent metabolic decompensation and performed as an enzyme replacement therapy. We retrospectively evaluated the outcomes of patients with PA and analyze the appropriate timing of living donor liver transplantation (LDLT).

METHODS

We reviewed 12 children with PA who underwent LDLT, who were divided into early (period from the first episode of metabolic decompensation to LDLT < 1 year; n = 6) and late (> 1 year; n = 6) indication groups depending on the timing of LDLT.

RESULTS

The patient and graft survival rates were 100% in 12 children with PA, and the median observation period was 61 months (5-193 months). None of the patients experienced any episodes of metabolic decompensation after LDLT. The timing of LDLT did not influence the incidence of surgical complications. Two patients in the late indication group had episodes of cardiac arrest and long QT syndrome before LDLT, and one patient showed prolongation of QT interval after LDLT. Two of the six patients in the late indication group had findings of metabolic stroke of the brain on MRI before LDLT. Although LDLT improved the findings of metabolic stroke, a decrease in development quotient score was shown in the post-LDLT course.

CONCLUSIONS

LDLT may be an effective therapeutic option for improving metabolic control. Early LDLT might be help prevent cardiomyopathy and neurological impairment.

Improved survival of pediatric deceased donor liver transplantation recipients after introduction of the pediatric prioritization system: Analysis of data from a Japanese national survey

BACKGROUND

In Japan, there has never been a national analysis of pediatric deceased donor liver transplantation (pDDLT) based on donor and recipient factors. We constructed a Japanese nationwide database and assessed outcomes of pDDLT focusing on the pediatric prioritization system introduced in 2018.

METHODS

We collected data on pDDLTs (<18 years) performed between 1999 and 2021 from the Japan Organ Transplant Network and Japanese Liver Transplantation Society, identified risk factors for graft survival and compared the characteristics and graft survival in pDDLTs conducted before and after the introduction of the pediatric prioritization system.

RESULTS

Overall, 112 cases of pDDLT were included, with a 1-year graft survival rate of 86.6%. Four poor prognostic factors were identified: recipient intensive care unit stay, model for end-stage liver disease/pediatric end-stage liver disease score, donor cause of death, and donor total bilirubin. After the introduction of the system, allografts from pediatric donors were more reliably allocated to pediatric recipients and the annual number of pDDLTs increased. The 1-year graft survival rate improved significantly as did pDDLT conditions indicated by the risk factors.

CONCLUSIONS

Under the revised allocation system, opportunities for pDDLT increased, resulting in favorable recipient and donor conditions and improved survival.

Experience and Results of Liver Transplantation in Patients With Alagille Syndrome at Our Center

OBJECTIVES

Alagille syndrome is an autosomal recessive disorder with multisystemic involvement. Patients with Alagille syndrome have many accompanying anomalies such as atypical facial appearance, posterior embryotoxon, butterfly vertebra, cardiac anomalies, and biliary problems. Liver and heart complications can determine the mortality and morbidity of patients with Alagille syndrome. The scarcity of intrahepatic bile ducts leads to cholestatic liver damage. In the heart, although the disease most commonly causes peripheral pulmonary stenosis, patients can present with various structural heart diseases. These cardiac anomalies make intraoperative and postoperative management difficult in patients who need liver transplant. Here, we present 10 cases of liver transplant due to Alagille syndrome.

MATERIALS AND METHODS

From 1988 to the present, our center performed 724 liver transplants, with 366 being pediatric cases; among these, 10 were due to Alagille syndrome. We retrospectively examined patient morphological findings, cardiac pathology, and perioperative complications.

RESULTS

Average weight and age of patients were 11 kg and 4.9 years, respectively. Eight patients had atypical facial appearance, 5 had posterior embryotoxon, and 6 had butterfly vertebra. Portoenterostomy (Kasai procedure) was performed in 3 patients because of suspicion of early biliary atresia. Cardiac pathology was present in 8 patients, with peripheral pulmonary stenosis being the most common (present in 8 patients). One patient had cardiac catheterization, with right ventricular and pulmonary artery pressures measured at 110 and 37 mm Hg, respectively. Two patients required preoperative pulmonary angioplasty. Two patients had double superior vena cava. No complications occurred in any patient during the anhepatic phase with appropriate volume replacement. No patients had early mortality.

CONCLUSIONS

Cardiac anomalies should be identified in patients with Alagille syndrome to minimize complications before liver transplant. If necessary, cardiac catheterization should be performed for pulmonary stenosis. Peripheral pulmonary stenosis does not constitute an absolute contraindication to liver transplant.

Combined liver-kidney transplantation in pediatric patients

Combined liver-kidney transplantation (CLKT) is a surgical procedure that involves transplanting both liver and kidney organs. There are two types of CLKT: simultaneous liver-kidney transplantation (smLKT) and sequential LKT (sqLKT). CLKT accounts for a small percentage of liver transplantations (LTs), particularly in pediatric cases. Nevertheless, the procedure has demonstrated excellent outcomes, with high survival rates and lower rejection rates. The main indications for CLKT in pediatric patients differ somewhat from that in adults, in which end-stage kidney disease after LT is the major indication. In children, congenital diseases are common reason for performing CLKT; the examples of such diseases include autosomal recessive polycystic kidney disease with congenital hepatic fibrosis which equally affects both organs, and primary hyperoxaluria type 1, a primary liver disease leading kidney failure. The decision between smLKT or sqLKT depends on the dominant organ failure, the specific pathophysiology, and available organ sources. However, there remain significant surgical and societal challenges surrounding CLKT. Innovations in pharmacology and genetic engineering have decreased the necessity for CLKT in early-diagnosed cases without portal hypertension or kidney replacement therapy. Nonetheless, these advancements are not universally accessible. Therefore, decision-making algorithms should be crafted, considering region-specific organ allocation systems and prevailing medical environments.

Chromatin accessibility analysis suggested vascular induction of the biliary epithelium via the Notch signaling pathway in the human liver

The biliary epithelial cells (cholangiocytes) in the liver originate from undifferentiated liver parenchymal cells (hepatoblasts) that are located adjacent to the portal vein. This differentiation process is driven by Notch signaling, which is recognized for generating salt-and-pepper (fine-grained) patterns, in contrast to one- or two-cell layer (spatially confined) patterning in cholangiocyte differentiation. It is unclear how Notch signaling acts and localizes only in cholangiocytes. A computer simulation study suggested that low production rates of the ligands or receptors of Notch signaling are crucial for the spatially confined patterning, although biochemical examination is lacking. Here, we analyzed a publicly available single-cell ATAC-sequencing dataset from human fetal liver samples. We showed high chromatin accessibility for the ligands only in vascular cells, while that for the receptor is limited to a small population of hepatoblasts. This finding strengthens the previously proposed idea that low production rates of the ligands or receptors of Notch signaling enable vascular induction of cholangiocytes.