Wallach's Interpretation of Diagnostic Tests: Pathways to Arriving at a Clinical Diagnosis (889 page)

   
Abnormal:
examples include deletion of the genomic region, additional copies of region, and positional rearrangement of region

   
Chromosome analysis

   
Normal:
46,XY (male) or 46,XX (female)

   
Abnormal:

   Numeric: incorrect chromosome number (e.g., +21 in Down syndrome)

   Structural: abnormal chromosome structure (e.g., deletion of the chromosome 5 short arm (5p−) in Wolf-Hirschhorn syndrome, translocation such as t(9;22) in CML)

   Limitations

   
FISH:
A targeted test, it cannot provide the total genomic assessment provided by conventional chromosome analysis.

   
Chromosome analysis:
requires
dividing cells
; therefore, all submitted specimens must contain viable cells that can be cultured in the laboratory.

D
-DIMERS
*

   Definition

   Plasma
D
-dimers are fibrin derivatives generated by the action of plasmin on cross-linked fibrin fragments D, indicating that the clotting mechanism had been activated and thrombin generated. Although it is a direct marker of active fibrinolysis, it is an indirect, but very useful, marker of ongoing coagulation.

   
Normal range:
<0.2 μg/mL for the latex assay; <1.1 mg/L for the ultrasensitive immunoturbidimetric test.

   Use