Hematological, Biochemical Properties, and Clinical Correlates of Hemoglobin S Variant Disorder: A New Insight Into Sickle Cell Trait

The sickle cell trait (SCT) disorder possesses a clinical heterogeneity ranging from a symptomless condition to sudden death. This study aimed to develop a diagnostic approach that helps the characterization and identification of SCT from normal subjects and sickle cell disease (SCD) patients, and to assess its severity.Sixty controls, 24 SCD patients and 31 SCT subjects were assessed clinically, radiologically and by laboratory investigations.Of the SCT subjects, 12.8% were symptomatic (3.2% anemic, 6.4% hemolytic crisis, and 3.2% painful crises). Anemia was normocytic in 66.6%, and normochromic and polychromatic in 33.4%. Significantly lower red blood cells (RBCs), hemoglobin (Hb), mean corpuscular volume (MCV), mean corpuscular hemoglobin (MCH), hematocrit (Hct), Shine and Lal index (SL), and hemoglobin A (Hb A), and higher mean corpuscular hemoglobin concentration (MCHC), red cell distribution width (RDW), Ricerca index (RI), and Huber-Herklotz index (HH) were found in SCT subjects compared with the controls. Hb A and hemoglobin S (Hb S) were excellent in discriminating SCT from SCD (cut-off for SCT50% and40%) followed by Hct, MCHC, Hb, Green and King index (GK), and England and Fraser index (EF) (cut-off for SCT33%,32,11,71, and10, respectively). Radiologically normal findings were detected in 87% of SCT subjects; they had nearly normal liver and renal function tests (except one case each). A schematic diagnostic paradigm for SCT was proposed.This study allowed understanding of SCT in various aspects, i.e., clinical, hematological, biochemical and radiological. Thus, it could help prevention of the Hb S variant disorder and proper management of carriers. This might be applied in pre-marital screening, particularly in those with family history of Hb S disorder.