Comparison of total cellular DNA, mRNA, and rRNA levels between normals and Down syndrome patients.

Two recent studies have suggested that the absolute cellular RNA and/or DNA levels in Down syndrome (DS) may be unusual compared to normals and may be linked to phenotypic expression (Pash et al., 1990; Dahl et al. 1988). We have extended these two studies by directly quantitating and comparing the total cellular mRNA, rRNA, and DNA levels in fibroblasts and lymphocytes derived from normal and DS individuals. The assay methods used, which allowed us to present the various nucleic acids levels in picograms per cell, did not reveal any significant difference between the two groups.