Aberrant concentrations of liver-derived plasma albumin mRNA in liver pathologies.

BACKGROUND: We hypothesized that liver-derived mRNA, such as ALB (albumin) mRNA, would be released into human plasma with liver cell death. METHODS: We genotyped ALB mRNA molecules in samples of plasma and whole blood from liver and bone marrow transplant recipients by RNA single-nucleotide polymorphism analysis. Plasma and whole blood ALB mRNA genotypes were compared with the DNA genotypes of the recipients and donors. A reverse-transcription quantitative real-time PCR assay was used to measure plasma ALB mRNA concentrations in 107 patients [hepatocellular carcinoma (HCC), cirrhosis, or chronic hepatitis B (CHB)] and 207 healthy controls. RESULTS: The RNA genotype data revealed ALB mRNA in plasma to be liver derived, whereas tissue compartments other than the liver also contributed to the ALB mRNA detected in whole blood. Statistically significant increases in plasma ALB mRNA concentrations were observed for HCC, cirrhosis, and active CHB, compared with controls. A cutoff of 835 copies/mL of plasma ALB mRNA identified by ROC curve analysis showed 85.5% diagnostic sensitivity and 92.8% diagnostic specificity for the detection of liver pathologies. Only 21.5% of patients with liver pathologies had increased alanine aminotransferase (ALT) activities, whereas 73.8% had increased plasma ALB mRNA concentrations. Only 48.6% of the HCC patients had increased serum alpha-fetoprotein concentrations, whereas 91.4% had increased plasma ALB mRNA concentrations. CONCLUSIONS: ALB mRNA is liver specific in plasma, but not in whole blood. Plasma ALB mRNA is increased in some liver pathologies and may be more diagnostically sensitive than alpha-fetoprotein and ALT.

Noninvasive prenatal diagnosis of monogenic diseases by digital size selection and relative mutation dosage on DNA in maternal plasma.

Prenatal diagnosis of monogenic diseases, such as cystic fibrosis and beta-thalassemia, is currently offered as part of public health programs. However, current methods based on chorionic villus sampling and amniocentesis for obtaining fetal genetic material pose a risk to the fetus. Since the discovery of cell-free fetal DNA in maternal plasma, the noninvasive prenatal assessment of paternally inherited traits or mutations has been achieved. Due to the presence of background maternal DNA, which interferes with the analysis of fetal DNA in maternal plasma, noninvasive prenatal diagnosis of maternally inherited mutations has not been possible. Here we describe a digital relative mutation dosage (RMD) approach that determines if the dosages of the mutant and wild-type alleles of a disease-causing gene are balanced or unbalanced in maternal plasma. When applied to the testing of women heterozygous for the CD41/42 (-CTTT) and hemoglobin E mutations on HBB, digital RMD allows the fetal genotype to be deduced. The diagnostic performance of digital RMD is dependent on interplay between the fractional fetal DNA concentration and number of DNA molecules in maternal plasma. To achieve fetal genotype diagnosis at lower volumes of maternal plasma, fetal DNA enrichment is desired. We thus developed a digital nucleic acid size selection (NASS) strategy that effectively enriches the fetal DNA without additional plasma sampling or experimental time. We show that digital NASS can work in concert with digital RMD to increase the proportion of cases with classifiable fetal genotypes and to bring noninvasive prenatal diagnosis of monogenic diseases closer to reality.