Value of PCR in the detection of B-thalassemia gene mutations among silents heterozygous carriers: a mulit-stage study

ABSTRACT

The detection of heterozygous [beta-thalassemia carriers is very important, as they transmit the [3 beta- thalassemia gene to their offspring, for genetic counseling and prenatal diagnosis. The screening of carriers is routinely performed by measuring red blood cells [RBCs] indices and the level of hemoglobin A[2] [HbA[2]]. However, in a considerable number of cases results are equivocal. So this multi-stage study was planned to detect different gene mutations among [Beta-thalassemia trait individuals, with equivocal hematological results age [silent carriers] by PCR. One hundred parents of 50 thalassemic children, besides 20 control age- and sex-matched individuals served as the subjects of this study. Serum iron, hemoglobin [Hb], RBCs indices [HCT, MCV, MCH and MCHC], reticulocytic counts, and one point osmotic fragility [OPOF] test were performed to all subjects. Meanwhile, qualitative detection of [beta -thalassemia mutations, using allele specific oligonucleotides [ASO] was performed to 25 carriers with normal serum iron, RC, OPOF. and/or normal HbA[2] [silent carriers]. The mutations at IVS 1-110, IVS 1-6, IVS I- 1] represented the most common mutations, accounting for 36%,20%, and 12%, respectively. Meanwhile, 3/25 [12%] of mutations were uncharacterized. The sensitivity of OPOF test, HbA[2] by chromatography and PCR in the detection of [beta-thalassemia trait accounted for 86%, 83% and 88%, respectively.Its concluded that for silent carriers, with normal serum iron, RC, RBCs indices, OPOF test and/or normal HbA[2] PCR should be performed