Prevention is better than Treatment
Evaluation of Glucose - 6 - Phosphate Dehydrogenase Activity : a new Quantitative Method suitable for neonatal screening
J. RECLOS Ph.D. 1.,
CHRISTINE J. HATZIDAKIS M.Sc. 1,
RUDOLF A. KRUITHOF 2
and KLEOPATRA H. SCHULPIS M.D., Ph.D. 3*
1 R&D DIAGNOSTICS Ltd, 41 El.Venizelou Street, 15561 Holargos, Greece
2 QUANTASE Limited, 3, Riverview Business Park, Friarton, Perth, PH2 8DF, Scotland, UK.
3* INSTITUTE OF CHILD HEALTH, Aghia Sofia Children Hospital, 11527 Athens,
* To whom all correspondence should be addressed.
Glucoso-6-Phosphate Dehydrogenase (G6PD) deficiency is by far the most common genetic disease affecting more than 200.000.000 people worldwide, so neonatal screening for it has been well established. In Greece, where this disease is prevalent, affecting an average of 5% of the male population, neonatal screening for this deficiency has been established for the last 17 years. Screening is centrally performed in the Institute of Child Health in Athens (1).
More than half of the severe jaundice cases among male newborns are related to G6PD deficiency in Greece, Sephardic Jewish and China (2,3). Additionally, the fall of glucose availability after correction of hyperglycaemic patients with type I Deabetes Mellitus is proposed as capable of inducing haemolysis in G6PD deficiency (5).
Therefore, we conducted the present study in order to evaluate the rate at which the loss of G6PD activity is taking place in vitro and determine the maximum post collection time that would guarantee trustworthy results.
The results presented herein give evidence of a negative effect of temperature on the G-6-PD activity content of the samples.
They also show that temperature affects samples differently; a finding that needs further investigation since it definitely indicates a multi-parametric influence. This was even true in blood derived from twins which may be attributed in differences occurred during blood drawing since handling and storage of the samples thereafter was identical for all samples. Individual parameters like the age of the red blood cells may also contribute to these discrepancies.
It is clearly shown that temperature is definitely not the only factor responsible for the loss of G-6-PD activity. Whole blood samples stored at room temperature for more than two weeks showed no apparent loss of activity in contrast to dried blood spots stored under the same conditions. Furthermore, most whole blood samples retained more than 85% of their initial activity after 2 months. Since the only difference between these samples is the fact that the latter are dried, we assume that there is a protective factor in whole blood, which retains the enzyme activity. This factor may be (i) the intact red blood cell itself, which may provide a protective microenvironment for the enzyme, (ii) the aging of the red blood cells or (iii) any other soluble, surface or cytoplasmic factor. Further work is now in progress to elucidate this finding.
This work proves that time lost during the transportation of the Gurthie cards from the Maternity Hospitals to screening centres should be kept to a minimum. Fast delivery of cards and/or the use of heat-insulated envelopes may be a solution, though the latter can not be guaranteed.
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Page last edited on 05/07/2005