The gene frequency for (--SEA/) deletional alpha-thalassaemia is high
in Southeast Asian populations. We report a simple immunocytological t
est that is highly sensitive and specific for the detection of adult c
arriers of the (--SEA/) deletion. We prospectively studied 296 consecu
tive adult blood samples. All 41 with the (--SEA/) deletion had a posi
tive test; all but 1 of the 165 non-carriers were negative. This test,
whose major requirement is a fluorescence microscope, should be usefu
l to identify couples at risk of conceiving fetuses with homozygous al
pha-thalassaemia.