دانلود رایگان مقاله انگلیسی HbS-Sicilian (??) - تالاسمی: یک سلول نادر داسی شکل - هینداوی 2017

Sickle cell disease (SCD) is caused by a mutation in the sixth codon of the ?-globin gene on chromosome 11, which leads to a single amino acid substitution (glutamine to valine). Sickle-(??) 0 -thalassemia is a rare variant of sickle cell disease (delta-beta thalassemia occurring in association with sickle hemoglobin, HbS), sparsely reported in literature, and has been associated with symptomatology necessitating careful monitoring and follow-up. We describe a patient who presented with a newborn screen reported as “FS” and a negative family history for sickle cell disease and sickle cell trait. Subsequent gene sequencing studies demonstrated the presence of Sickle-(??) 0 -thalassemia. Clinical course has remained relatively stable for this patient now at 18 months of age without any SCD related symptomatology or complications. As this is a rare variant of SCD with potential complications, it is important to establish diagnosis towards planning comprehensive care.

3. Discussion

??-thalassemia is characterized by decreased or absent synthesis of the delta- and beta-globin chains with a compensatory increase in expression of fetal gamma-chain synthesis. The condition is found in many ethnic groups but is most common in Greece and Italy. Homozygotes for ??- thalassemia have 100% HbF and, because of the increased synthesis of HbF, may have thalassemia intermedia rather than thalassemia major [6, 7]. The heterozygous form of the condition phenotypically resembles B thalassemia trait but HbA2 is often normal while HbF is elevated varying from 5% to 20% [7]. Since homozygous ??-thalassemia presents an identical HPLC finding as homozygotes of hereditary persistence of fetal hemoglobin of 100% HbF, the clinical findings of mild hemolytic anemia rule in favor of ??-thalassemia rather than HPFH [8]. Family studies also play a role in eliciting the correct diagnosis (thalassemic features). Sicilian (??) 0 -thalassemia presents a deletion of 13,379- bp spanning ?-IVS2 to a region located 3? from the ?-globin gene within an L1 repeat. [9]. Sickle-(??) 0 -thalassemia is a rare SCD variant that has been sparsely reported worldwide [4, 5]. These cases were described to have mild microcytic anemia, as well as SCD complications which include multiple episodes of VOC (in some cases this occurred prior to diagnosis), osteomyelitis, multifocal avascular necrosis, cholelithiasis, and osteonecrosis [4, 5].