Influence of alpha-thalassemia trait on spleen function in sickle cell anemia patients with high HbF.

Spleen function was studied in a group of 20 Kuwaiti SS patients (aged 2-12 years), using 99mTc-labeled tin colloid scintigraphy. They were screened for the alpha-thalassemia determinants which are prevalent in the Arabian Peninsula [-alpha (3.7 kb) deletion, alpha2-globin gene polyadenylation signal (AATAAA => AATAAG) mutation, and 5' IVS-I splice junction pentanucleotide (GAGGTGAGG => GAGG) deletion] with a combination of polymerase chain reaction and allele-specific oligonucleotide (ASO) hybridization techniques. The patients were divided into three groups depending on the result of their colloid uptake. Group I consisted of 7 patients (35.0%) with normally visualized spleens, Group II consisted of 5 (25.0%) with partial visualization, and in Group III there were 8 (40.0%) in whom the spleen was not visualized at all. The significant distinguishing features among those in Groups I and III were mean corpuscular volumes (MCVs) of 74.1 +/- 5.1 and 90.1 +/- 6.6 fl (P<0.0001) and mean corpuscular hemoglobins (MCHs) of 22.4 +/- 2.7 and 27.5 +/- 4.0 pg (P<0.05), respectively. The overall frequency of alpha-thalassemia determinants in the study was 35.0%; however, the frequencies in Groups I, II, and III were 57.1, 30.0, and 18.8%, respectively. alpha-Thalassemia trait, therefore, appears to be associated with normal splenic function in these patients.