Quick Review Cards for Medical Laboratory Science

Specimens for MDxcontinued

Molecular Diagnostics

(MDx) Review 546

SPECIMEN USE/COMMENTS

Tissue

Hair/nails

Formalin-fixed, paraffin embedded tissue: DNA degraded to low molecular weight (MW) fragments.

Can usually be amplified but Southern blot can’t be used (requires high MW DNA).

Fresh tissue, snap-frozen tissue, or tissue frozen at –80°C in optimal cutting temperature compound

(OCT): yields higher MW DNA. OCT must be completely removed before DNA extraction.

Forensic analysis.