Specimens for MDx
Molecular Diagnostics
(MDx) Review 545
SPECIMEN USE/COMMENTS
Whole blood/plasma
Bone marrow
Urine
Feces
Cerebrospinal, synovial, pleural,
pericardial, ascetic fluids
Amniotic fluid, choronic
villus sampling (CVS)
Buccal cells
Nucleated cells are source of DNA. Some recent techniques can detect non-nuclear DNA in plasma.
Nucleic acid of infectious agents often detected in plasma, sometimes in host DNA. Hemolysis can
interfere with amplification.DNA obtained from nucleated cells.Detection of Chlamydia, CMV, & BK virus (associated with rejection of transplanted kidney).Detection of intestinal pathogens. Analysis of stool DNA proposed for detection of colorectal cancer.Detection of infectious agents & cancer cells.Dx of sickle cell anemia, Tay-Sachs disease, thalassemia, other chromosomal abnormalities &
inherited disorders. Usually grown in tissue culture to ↑# of cells for DNA extraction.Good source of DNA, especially for genotyping bone marrow recipients & patients who have been
recently transfused. Avoid use of mouthwash with phenol or ethanol. Use sterile Dacon or rayon
swabs with plastic shafts. Calcium alginate swabs & wooden shafts may contain substances that
inhibit PCR.continued...