The effect of alpha-thalassemia on cord blood red cell indices and interaction with sickle cell gene

Background: alpha -thalassemia is known to be prevalent in the Eastern regi on of Saudi Arabia. There are no large-scale reports regarding the effect o f alpha -thalassemia on red cell indices of cord blood from Saudi Arabia. S imilarly, there are no reports regarding the interaction of alpha -thalasse mia and the sickle cell gene in relation to red cell indices in cord blood. To address these issues, we undertook a study on neonatal cord blood sampl es. Materials and Methods: In a prospective study, cord blood samples from 504 neonates from the Qatif area of the Eastern Province of Saudi Arabia were a nalyzed for complete blood counts (CBC) and cellulose acetate Hb electropho resis. Hb S was confirmed by citrate agar Hb electrophoresis. Results: There were 243 case samples with normal Hb electrophoresis (Hb A 2 7.2 +/-7% and Hb F 72.6 +/-7.7%). Their mean Hb (g/dL), RBC (x10(12)/L), He t (%), MCV (fl), MCH (pg), MCHC (g/dL), RDW-SD (fi) and RDW-CV (%) were 15. 05 +/-1.6, 4.5 +/-0.5, 47.4 +/-5.3, 106 +/-8, 33.6 +/-2.3, 31.8 +/-1.7, 69. 2 +/-9.5 and 17.9 +/-1.7, respectively. There were 136 cases with alpha -th alassemia trait (alpha TT), 57 cases with sickle cell trait (SCT) and 50 ca ses of sickle cell trait with alpha -thalassemia trait (SCT/alpha TT). Ther e were 10 cases of Hb H disease (6 definite), including one with sickle cel l disease (SCD) and two with SCT, Hb Bart's 23.9%-43.6%; four probable with Hb Bart's 10.9%-16.1%, and one with SCT. The effect on red cell parameters in Hb H disease were most pronounced. In addition, there were seven cases of SCD, four of whom had coexistent alpha -thalassemia trait (SCD/alpha TT) . Conclusion: The prevalence of alpha -thalassemia in this cohort of Saudi po pulation was 39.99%. Hb H disease appeared as common as SCD. Sickle cell ge ne was seen in 23.4% of neonatal samples. a-thalassemia gene significantly reduces MCH, MCV, RDW-SD, Hct, Hb, and increases RBC count in both normal o r sickle cell trait neonates. Generally, the variation of red cell paramete rs is directly proportional to the amount of Hb Bart's in the cord blood. S ickle cell gene in itself produces low MCV, RDW-SD and MCH in cord blood. F urther, normal reference values for red cell parameters of cord blood are e stablished.