© 2000 by Oxford University Press
Xmn I polymorphic site in Yemeni sickle cell disease patients
A Medical Biochemistry Department and WHO Collaborating Centre for Haemoglobinopathies, Thalassaemias and Enzymopathies, College of Medicine and B Department of Biochemistry, College of Science, King Khalid University Hospital, PO box 2925, Riyadh 11461, Saudi Arabia Z Corresponding author
To investigate the molecular basis of severe clinical presentation in sickle cell disease (SCD) patients in Yemen, this study was conducted on 30 Yemeni SCD patients living in Riyadh and attending King Khalid University Hospital. Seven individuals without SCD were used as controls. Haematological parameters, red cell indices, HB A2 and Hb F levels were estimated and haemoglobin variant were identified on electrophoresis profiling. DNA was extracted from the buffy coat separated from fresh blood samples and was treated with the restriction endonculease: Xmn I. The fragments generated were separated on electrophoresis, transferred to nitrocellulose and hybridized to a 32P-labelled probe of 
-globin gene. After extensive washing, two bands, 8.1 kb and 7.0 kb in size, were obtained. The frequency of occurrence of the presence of Xmn I polymorphic site (7.0 kb fragment) and its absence (8.1 kb fragment) were documented. The results in Yemeni SCD patients were compared with the results obtained previously in Saudi Arabs. Of the 30 SCD patients from Yemen 29 had only the 8.1 kb fragment and one had only the 7.0 kb fragment. This gave the frequency of 0.966 for the absence (-) and 0.033 (+) for the presence of Xmn I polymorphic site. This is the same result as that reported earlier for SCD patient from southwestern Saudi Arabia [(-)=0.966; (+)=0.033] but is significantly different from that reported in the eastern province [(-)=0.068; (+) 0.932)] of Saudi Arabia. This paper presents the nature of molecular linkage in SCD patients from Yemen.