MR elastography-based staging of liver fibrosis in Fontan procedure associated liver disease is confounded by effects of venous congestion.

AIM: To compare targeted and global liver stiffness measured by magnetic resonance elastography (MRE) with liver biopsy in patients who have undergone the Fontan procedure, and to assess the relationship between liver stiffness and fibrosis stage. MATERIALS AND METHODS: Targeted and global liver stiffness was compared with a quantification of liver fibrosis measured by percentage of Sirius Red (%SR) staining of biopsy samples. MRE values were compared with three other biopsy-scoring methods: Ishak, Scheuer/Ludwig-Batts/Metavir, and congestive hepatic fibrosis score (CHFS). Additionally, in patients who had two or more MRE studies, global liver stiffness was compared for longitudinal assessment. RESULTS: Thirty-four patients were included in the study, with a mean age of 16.2 years. There was no statistically significant correlation between MRE-derived liver stiffness and Ishak score, Metavir score, %SR staining, and CHFS score. Twenty patients had multiple MRE studies, with a mean age of 16.5 years, and these showed a statistically significant increase in mean liver stiffness from 3.72 to 4.68 (26% increase) within an average period of 24 months. CONCLUSIONS: The lack of correlation of liver stiffness with fibrosis stage observed in this study indicates that the effects of venous congestion in Fontan patients can confound the use of liver stiffness as a biomarker for fibrosis as assessed by percentage of SR staining, Ishak score, Metavir score, and CHFS score. These results provide motivation for further development of magnetic resonance imaging-based biomarkers to increase the specificity in the assessment of Fontan-associated liver disease. A steady increase in liver stiffness observed in these patients may be useful for longitudinal follow-up of liver health.

Proliferation-associated SNF2-like gene (PASG): a SNF2 family member altered in leukemia.

To identify genes involved in cell growth and/or apoptosis in leukemia, differential display was used to identify mRNAs that showed altered expression levels after cytokine withdrawal from the cytokine-dependent MO7e cell line. Sequence analysis of one transcript that showed a profound decrease in expression after cytokine withdrawal revealed it to be a member of the SNF2 family of chromatin remodeling ATPases. This cDNA had a 2514-nucleotide (838-amino acid) open reading frame and encoded an additional 230 amino acids at the NH2 terminus compared with the murine homologue, lsh, and the human counterpart, Hells. This gene locus has been designated SMARCA6 (SWI/SNF2-related, matrix-associated, actin-dependent regulator of chromatin, subfamily A, member 6). The highest levels of mRNA expression in humans are observed in proliferative tissues such as the thymus, testis, and bone marrow. Whereas cytokine withdrawal in MO7e cells leads to apoptosis and decreased mRNA expression, growth arrest without the induction of apoptosis of MO7e cells also leads to down-regulation of mRNA expression, suggesting an association with cell proliferation and not suppression of apoptosis. Nuclear localization of this SNF2-like putative helicase is dependent on a nuclear localization sequence located in the NH2-terminal region. Based on sequence homology to other SNF2-like helicases, the pattern of tissue expression, and the association of expression with cell proliferation, we refer to the protein product as proliferation-associated SNF2-like gene product [PASG (D. W. Lee et al., Blood, 94: 594a, 1999)]. Examination of acute myelogenous leukemia and acute lymphoblastic leukemia samples revealed a high frequency of a PASG transcript containing an in-frame 75-nucleotide deletion, which codes for a conserved motif known to be critical for the transactivation activity of a related yeast SWI/SNF polypeptide. These results extend our knowledge of this SNF2-like family member and suggest a role for PASG in leukemogenesis.