A prospective assessment of the inter-laboratory variability of biochemical markers of fibrosis (FibroTest) and activity (ActiTest) in patients with chronic liver disease

BACKGROUND: Biochemical markers for liver fibrosis (FibroTest) and necroinflammatory features (ActiTest) are an alternative to liver biopsy in patients with chronic hepatitis C. Our aim was to assess the inter-laboratory variability of these tests, and their 6 components (γ-glutamyl transpeptidase, alanine aminotransferase, α(2)-macroglobulin, haptoglobin, apolipoprotein A1, and total bilirubin) and to identify factors associated with this variability. RESULTS: Serum of 24 patients with chronic hepatitis C or severe alcoholic liver disease were prospectively recorded and analyzed in one reference center and in 8 additional laboratories. When γ-glutamyl transpeptidase and alanine aminotransferase were expressed in international units, there was no significant difference between laboratories in the results of FibroTest or ActiTest; kappa statistics were greater than 0.50 with only 0.8% of cases (3/384) with a discordance of more than one stage. The main factor significantly associated with variability was the expression of γ-glutamyl transpeptidase and alanine aminotransferase, as multiples of upper limit of reference values. The use of standardized method with pyridoxal phosphate reduced the variability of alanine aminotransferase expression, and standardized original Szasz method reduced the variability of γ-glutamyl transpeptidase expression. CONCLUSIONS: The variability of FibroTest and ActiTest was acceptable without clinical consequences for the prediction of the stage of liver fibrosis and grade of activity. Standardized methods and assay calibration should be used and expression of alanine aminotransferase and γ-glutamyl transpeptidase in multiples of the upper limit of reference values should not be employed

Relations between C9orf72 expansion size in blood, age at onset, age at collection and transmission across generations in patients and presymptomatic carriers

International audienceA (GGGGCC)n repeat expansion in C9orf72 gene is the major cause of frontotemporal dementia (FTD) and amyotrophic lateral sclerosis (ALS). The relations between the repeats size and the age at disease onset (AO) or the clinical phenotype (FTD vs. ALS) were investigated in 125 FTD, ALS, and presymptomatic carriers. Positive correlations were found between repeats number and the AO (p < 10e-4) but our results suggested that the association was mainly driven by age at collection (p < 10e-4). A weaker association was observed with clinical presentation (p = 0.02), which became nonsignificant after adjustment for the age at collection in each group. Importantly, repeats number variably expanded or contracted over time in carriers with multiple blood samples, as well as through generations in parent-offspring pairs, conversely to what occurs in several expansion diseases with anticipation at the molecular level. Finally, this study establishes that measure of repeats number in lymphocytes is not a reliable biomarker predictive of the AO or disease outcome in C9orf72 long expansion carriers

Relations between C9orf72 expansion size in blood, age at onset, age at collection and transmission across generations in patients and presymptomatic carriers

A (GGGGCC)n repeat expansion in C9orf72 gene is the major cause of frontotemporal dementia (FTD) and amyotrophic lateral sclerosis (ALS). The relations between the repeats size and the age at disease onset (AO) or the clinical phenotype (FTD vs. ALS) were investigated in 125 FTD, ALS, and presymptomatic carriers. Positive correlations were found between repeats number and the AO (p < 10e 124) but our results suggested that the association was mainly driven by age at collection (p < 10e 124). A weaker association was observed with clinical presentation (p = 0.02), which became nonsignificant after adjustment for the age at collection in each group. Importantly, repeats number variably expanded or contracted over time in carriers with multiple blood samples, as well as through generations in parent-offspring pairs, conversely to what occurs in several expansion diseases with anticipation at the molecular level. Finally, this study establishes that measure of repeats number in lymphocytes is not a reliable biomarker predictive of the AO or disease outcome in C9orf72 long expansion carriers