Two different forms of homozygous sickle cell disease occur in Saudi Arabia

Abstract

Haematological, clinical and some molecular genetic features of homozygous sickle cell (SS) disease in Saudi Arabia have been compared in 33 patients from the Eastern Province (Eastern) and 30 from the South Western Province (Western). Eastern patients all had the Asian beta globin haplotype whereas Western patients were more variable but predominantly of the Benin haplotype. Eastern patients had more deletional alpha thalassaemia, higher total haemoglobin and fetal haemoglobin levels, and lower HbA2, mean cell volume, reticulocytes, and platelet counts. Clinically, Eastern patients had a greater persistence of splenomegaly, a more normal body build and greater subscapular skin fold thickness, and Western patients had more dactylitis and acute chest syndrome. Painful crises and avascular necrosis of the femoral head were common and occurred equally in both groups. The disease in the Eastern province has many mild features consistent with the higher HbF levels and more frequent alpha thalassaemia but bone pathology (painful crises, avascular necrosis of the femoral head, osteomyelitis) remains common. The disease in the West is more severe consistent with the Benin haplotype suggesting an African origin.

Epidemiology of sickle cell disease in Saudi Arabia

“…Acute chest syndrome in SCD children less than 12 years of age occurs less commonly in the East compared with the West (7.7-13.4% vs 22.6%, respectively) and recurrence rate is significantly lower in patients from the Eastern province 33. However, the difference in mortality rate from acute chest syndrome between both regions was not statistically significant 263033. Patients from the Eastern province had a more normal body build and greater subscapular skin fold 29.…”

“…Eastern patients have more deletional alpha thalassemia, higher total hemoglobin and fetal hemoglobin levels, and lower hemoglobin A2, mean cell volume, reticulocytes, and platelet counts 30. Clinically, the disease carries a mild or benign phenotype.…”

“…However, ‘benign’ is a relative term as patients with this type of disease have a different spectrum of disease with its acquired problems. For example, SCD patients from the Eastern province have a 27% risk of avascular necrosis of the femoral head compared with 8% to 12% in the African type 30–32. Late persistent splenomegaly is reported in 50% to 80% of patients, resulting in a higher risk of splenic complications such as sequestration crisis, chronic hypersplenism, splenic infarction and abscess, trauma, and rupture, and 20% required splenectomy 3031.…”

“…For example, SCD patients from the Eastern province have a 27% risk of avascular necrosis of the femoral head compared with 8% to 12% in the African type 30–32. Late persistent splenomegaly is reported in 50% to 80% of patients, resulting in a higher risk of splenic complications such as sequestration crisis, chronic hypersplenism, splenic infarction and abscess, trauma, and rupture, and 20% required splenectomy 3031. In the Western province, the frequency of splenomegaly is significantly less frequent 3031.…”

“…Late persistent splenomegaly is reported in 50% to 80% of patients, resulting in a higher risk of splenic complications such as sequestration crisis, chronic hypersplenism, splenic infarction and abscess, trauma, and rupture, and 20% required splenectomy 3031. In the Western province, the frequency of splenomegaly is significantly less frequent 3031. Acute chest syndrome in SCD children less than 12 years of age occurs less commonly in the East compared with the West (7.7-13.4% vs 22.6%, respectively) and recurrence rate is significantly lower in patients from the Eastern province 33.…”