Liver allograft pathology in healthy pediatric liver transplant recipients.

Liver transplantation offers excellent results for children with end-stage liver disease, and efforts should be directed toward maintaining long-term graft health. We evaluate graft pathology in healthy pediatric transplant recipients with low-maintenance immunosuppressive medications to assess whether protocol biopsies are helpful for adapting immunosuppression and protecting long-term graft function. Liver biopsies were performed on 60 healthy pediatric liver transplant recipients, and histological findings were correlated with laboratory, serological, and radiological results. Fourteen patients (23%) were diagnosed with acute or early chronic rejection, and immunosuppressive medications were increased in these children. Liver function tests did not correlate with histological findings. The incidence of fibrosis was 36% in transplant recipients five or more years after liver transplantation. We observed an unexpectedly high prevalence of rejection and fibrosis in children with no laboratory abnormalities, which led to changes in their immunosuppressive medications. Scheduled biopsies appear to be useful in pediatric transplant recipients with low immunosuppressive medications for early detection of morphological changes in liver transplants. Further studies are needed to evaluate whether adaption of immunosuppression helps to reduce tissue damage and the incidence of allograft dysfunction in the long term.

Hepatocerebral mitochondrial DNA depletion syndrome caused by deoxyguanosine kinase (DGUOK) mutations.

BACKGROUND: Autosomal recessive mutations in deoxyguanosine kinase (DGUOK) have been identified in the hepatocerebral form of mitochondrial DNA (mtDNA) depletion syndrome. OBJECTIVES: To describe the clinical spectrum of DGUOK-related mtDNA depletion syndrome in 6 children and to summarize the literature. RESULTS: We identified pathogenic mutations in DGUOK in 6 children with the hepatocerebral form of mtDNA depletion syndrome. We describe the clinical, neuroradiologic, histologic, and genetic features in these children. All children showed severe hepatopathy, while involvement of other organs (skeletal muscle and brain) was variable. We identified 5 novel mutations (1 of them in 2 children) and 2 previously described mutations. Three different mutations affected the initial methionine, suggesting a mutational hot spot. One of our patients underwent liver transplantation; pathologic findings revealed (in addition to diffuse hepatopathy) a hepatocellular carcinoma, implying a possible link between mtDNA depletion syndrome and tumorigenesis. CONCLUSION: We studied 12 children with infantile hepatoencephalopathies and mtDNA depletion syndrome and found pathogenic DGUOK mutations in 6, suggesting that this gene defect is a frequent but not an exclusive cause of the hepatic form of mtDNA depletion syndrome.