Daniel D'Agostino

Functional analysis of ABCB4 mutations relates clinical outcomes of progressive familial intrahepatic cholestasis type 3 to the degree of MDR3 floppase activity

Objective Progressive familial intrahepatic cholestasis type 3 (PFIC3) is a potentially lethal autosomal recessive liver disease associated with mutations in ABCB4, the gene encoding the canalicular translocator of phosphatidylcholine MDR3. While some affected children benefit from ursodeoxycholic acid (UDCA) therapy, others evolve to end-stage liver disease. We aimed to evaluate whether these different outcomes are related to the impact of ABCB4 mutations. Design Six children with PFIC3 were investigated by sequencing of ABCB4 exons and flanking intron-exon boundaries and by immunohistochemistry. ABCB4 missense mutations were phenotyped in vitro by assessing their effects on MDR3 expression, subcellular localisation, and phosphatidylcholine-translocating activity. The resulting data were contrasted with the clinical outcomes. Results Eight distinct ABCB4 mutations were identified: one nonsense, one splicing and six missense mutations, four of which (G68R, T201M, P479L, D459H) affected MDR3 expression level. G68R and D459H also led to retention of the protein in endoplasmic reticulum. Phosphatidylcholine efflux assays indicated that T201M, P479L, S978P and E1118K mutations impaired MDR3 activity to variable degrees. Three children with mutations that caused a total loss of MDR3 expression/function manifested progressive liver disease refractory to UDCA treatment. This was also the case in a patient carrying two different mutations that, in combination, resulted in a 90% reduction in total MDR3 activity. A favourable response to UDCA was achieved in two patients with estimated MDR3 activities of 50% and 33%, respectively. Conclusions These data provide experimental evidence of the correlation between the degree of MDR3 floppase activity and the clinical outcomes of PFIC3.

Liver transplantation as treatment for arterioportal fistulae.

The authors present the case of a 14-year-old boy with secondary portal hypertension caused by arterio-portal fistulae. Ascites, edema, severe abdominal pain, and steatorrhea developed in the patient. In an attempt to decrease arterioportal flow the authors carried out vascular embolization that was partially successful. A liver transplant was performed as a last therapeutic resource in view of the fact that it constitutes an accepted therapy for patients with severe liver disease. Orthotopic liver transplantation may be considered as another possible treatment of arterio-portal fistulae.

Hepatic cell transplantation in childhood. State of the art

To date, children who suffer from a certain type of illness such as hepatic failure, could benefit with a non conventional functional replacement as an alternative to liver transplantation. Deterioration and death of patients on waiting list encourage the search for alternatives methods within transplantation. Liver cell transplantation has become a potential alternative treatment whose validation as an alternative or as a bridge until the donor appears, will probably contribute to improve the quality of life and survival of the patients. The aim of this review is to describe the state of the art of hepatocyte transplantation in pediatric patients.