THE CORRELATION BETWEEN MICROSCOPIC EXAMINATION AND ERYTHROCYTE BAND-3 (AE1) GENE DELETION IN SOUTH-EAST ASIAN OVALOCYTOSIS

South-east Asian ovalocytosis status was determined by microscopical e xamination of peripheral blood samples collected from 137 individuals in Papua New Guinea.The examination was performed separately by 2 micr oscopists, one of whom was very experienced in examining peripheral bl ood films for the diagnosis of south-east Asian ovalycytosis and the o ther was recently trained. The samples were also analysed by polymeras e chain reaction (PCR) to determine ovalocytosis status by demonstrati ng a 27 base pair deletion in erythrocyte band 3 protein of the affect ed individuals. The microscopists were unaware of each other's results and of those obtained by PCR. Generally, there was very good agreemen t between the results obtained by both microscopists and the PCR. Alth ough there was considerable inter-observer variation in the final oval ocyte count between the 2 microscopists, this did not affect their abi lity to discriminate between ovalocytic and normocytic individuals.Tak ing the PCR results as the standard, for the first, more experienced o bserver, the most efficient ovalocyte count cut-off point was around 5 0%.At this ovalocyte count the sensitivity and specificity of microsco pical examination were 93.6% and 92.2%, and the positive and negative predictive values 86.3% and 96.5%, respectively. The second microscopi st generally underscored the ovalocyte counts and his most efficient c ut-off point was 20%, with sensitivity and specificity of 85.1% and 93 .3% and positive and negative predictive values of 87.0% and 92.3%, re spectively.