DENSE CELLS IN SICKLE-CELL-ANEMIA - THE EFFECTS OF GENE INTERACTION

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  • 1 January 1984
    • journal article
    • research article
    • Vol. 64  (5) , 1042-1046
Abstract
In an attempt to uncover potential genetic sources of the clinical diversity of sickle cell anemia, homozygous SS patients were characterized in the following ways: percentage of dense red blood cells (% F4:) as determined from Percoll-Stractan continuous density gradients, .alpha. gene deletion, average percentage of HbF (% HbF), Hb in g/dl, age and sex. Alpha 4 individuals apparently have a higher % F4 (mean 24% .+-. 15%) than .alpha. 3 individuals (mean 12% .+-. 8%) (%P < 0.005). Multivariate analysis demonstrated a significant correlation among % F4 levels and .alpha.-gene number and % HbF, and an interaction between the last two variables. The other variables considered did not significantly alter this model. With fewer samples, in the 1st 10 yr of life of SS individuals, the frequency of .alpha. gene deletion is 17%, which is comparable to that in the general black population, while in the group over 20 yr of age, the frequency rises to 49%, implying that .alpha. thalassemia is associated with longer survival. It apparently is necessary to consider sickle cell anemia not only as a single gene defect, but also as a disease whose clinical expression is the result of a group of genes capable of interacting at the phenotypic level.