An automated image analysis method for the measurement of neutrophil alkaline phosphatase in the prenatal screening of Down syndrome.
OBJECTIVE
(1) To develop an image analysis method for the measurement of neutrophil alkaline phosphatase (NAP); (2) To establish a correlation of urea-resistant fraction of NAP (URNAP)/NAP scoring between the manual and automated methods, and (3) to assess the value of URNAP/NAP in the prenatal screening of Down syndrome.


METHODS
Slides from 15 unaffected controls were blindly scored by both methods. The Pearson test was used for correlation analysis. Slides from 15 Down syndrome pregnancies and 25 unaffected controls were scored manually.


RESULTS
A coefficient r = 0.93 was obtained comparing the URNAP/NAP scores generated by the two methods. Average time for scoring by the automated method was 8 min. The median URNAP/NAP values for Down syndrome and unaffected controls were 112/86.1 and 51/51.5, respectively.


CONCLUSIONS
Scores obtained by both methods highly correlate. Automated scoring is threefold faster. Down syndrome cases have higher URNAP/NAP scores compared to unaffected controls, which suggests that URNAP/NAP is an extremely useful marker for mid-trimester prenatal screening.
Tafas
T
T
Department of Biology, University of Athens, Greece.
Cuckle
H S
HS
Nasr
S
S
Krivchenia
E L
EL
Resvani
E
E
Evans
M I
MI
D000469:Alkaline Phosphatase / Q000097:blood*; D001322:Autoanalysis; D004314:Down Syndrome / Q000175:diagnosis*; D005260:Female; D006801:Humans; D007091:Image Processing, Computer-Assisted; D009504:Neutrophils / Q000201:enzymology*; D011247:Pregnancy; D011296:Prenatal Diagnosis / Q000379:methods*
D000469:Alkaline Phosphatase