Relationship of haemoglobin F and alpha thalassaemia to severity of sickle-cell anaemia in the Eastern Province of Saudi Arabia

Abstract

To define the natural history of sickle cell anaemia a cord blood screening programme was initiated and during the first 3 years a total of 129 newborns with FS phenotype were detected, of whom 83 infants were followed up regularly. Forty-three of them had attained the ages of between 1 and 3 years and the analysis of their data revealed that in 21 of 43 cohort children (14 FS and 7 FS + Barts) who had almost identically raised levels of haemoglobin F, the clinical manifestations of the disease appeared to be influenced by the size of the RBC, with the microcytic group having a relatively milder clinical course as compared with the normocytics. Similar observations were made in about 50% (47/93) of non-cohort older children and adults with sickle-cell anaemia, suggesting that alpha thalassaemia in combination with increased levels of fetal haemoglobin was probably an important predictor of the clinical severity in patients with sickle-cell anaemia in the Eastern Province of Saudi Arabia.

Fibrocongestive splenomegaly in sickle cell disease: A distinct clinicopathological entity in the Eastern province of Saudi Arabia

“…Such mildness is postulated to be due to the cumulative effect of multiple factors, chief among them being the higher HbF levels. The inhibitory effect of HbF upon the process of RBC sickling by interfering with the formation of HbS polymers has been extensively documented; it has been further observed that patients having HbF levels >20% are more likely to have milder sickling manifestations in sickle cell disease [1,[3][4][5]7,11,22,25]. In the present study, 75% of total patients, belonging to the ''SCA with high HbF'' and ''S-b thalassemia'' groups, had HbF levels > 20%.…”

“…Other responsible factors postulated for the mild nature of sickle cell disease comprise the Asian haplotype of b S globin gene and the frequent co-occurrence of a-thalassemia in the Saudi population [7][8][9]11,[26][27][28]. The disease progression in the present study patient's cohort resembles that described for the Asian haplotype of b S globin gene [8,9,11,26,27].…”

“…Two distinctive patterns of sickle cell disease occur in western and eastern Saudi Arabia regions; the disease in western Saudi Arabia resembles that associated with Benin haplotype of b S globin gene. It is characterized by a high frequency of vascular occlusive crises, nephropathy, priapism, stroke, infections, major-type acute splenic sequestration crises, and early autosplenectomy [1][2][3][4][5][6][7][8][9][10][11]. Sickle cell disease in the eastern Saudi Arabia is typically associated with the Asian haplotype of b S globin gene and has been reported to be of mild nature with lower incidences of stroke, priapism, nephropathy, fewer vasoocclusive crises, late splenomegaly persistence, late and variable functional asplenia, and lower mortality [1][2][3][4][5][6][7][8][9][10][11].…”

“…Multiple responsible factors have been evaluated to explain this progression, the most widely accepted being the occurrence of Asian haplotype of b S globin gene, high levels of fetal hemoglobin (HbF), and frequent a-thalassemia [1][2][3][4][5][6][7][8][9].…”

Acute Chest Syndrome in Sickle Cell Disease in Saudi Arab Children in the Eastern Province

“…25,26 The mechanism by which genetic factors affect the severity of SCD is not known. Many authors have however implicated high Hb F [27][28][29] and alpha thalassemia. [30][31][32][33] ACS has been found to be inhibited by high Hb F levels.…”