Jassim et al. (1999) described a simple and robust technique to rapidly detect the hemoglobin alpha (T-Saudi) allele. A total of 32 individuals with proven Hb H disease were studied using a novel mismatched-primer PCR-RFLP approach. This technique involves performing PCR with one of the primers having a deliberately introduced mismatch. The mismatch introduces a StuI restriction enzyme site into the product, which can be cleaved using the restriction enzyme. Hb H levels in the analyzed patients ranged between 5-25% due to homozygosity for the alpha (T-Saudi) allele and compound and simple heterozygosity for various alpha thalassemia alleles. Jassim et al. (1999) indicated that compound heterozygotes for -alpha (3.7) and alpha (T-Saudi) mutations will provide a false homozygous pattern for alpha (T-Saudi) mutations.

Two years later, Jassim et al. (2001) utilized PCR amplification, PCR-RFLP, and differential PCR amplification to study the alpha-globin gene in 56 unrelated alpha-thalassemia individuals (age ranging from 14 days to 78 years). With the exception of two, all the other patients were found to have low MCV, MCH, and HbA2. The two exceptional cases were found to have concurrent beta-thalassemia or sickle cell trait. A total of five different alleles were found in the patient population. Of these, the alpha T-Saudi alpha allele was found to be the most common (53%), followed by the deletional -alpha (3.7 kb) allele (32%). The authors conceded that the high frequency of the Saudi allele could be due to a recruitment bias. Other alleles detected were alpha Hph alpha (12%), alpha T-Turkish alpha (1%) and -alpha (4.2 kb) allele (2%). Ten different genotype combinations were found in the study. Of these, homozygosity for the Saudi allele was responsible for all but three cases of HbH. Of the exceptions, one was heterozygous for the Saudi and the Turkish allele. Since both these alleles are poly A signal mutations, the severe phenotype is understandable. The second case was compound heterozygous for -alpha 3.7 and the Saudi allele, whereas the third exceptional case was homozygous for the -alpha 3.7 allele. Jassim et al. (2001) postulated that in both these cases, the -alpha 3.7 allele may be harboring an additional thalassemia mutation. [Jassim N, Al-Arrayed S, Gerard N, Al-Mukharraq H, Al-Ajami A, Ducrocoq R, Nagel RL, Krishnamoorthy R. Molecular basis of alpha-thalassemia in Bahrain. Bahrain Med Bull 2001; 23(1):3-7.]

Adekile et al. (1994) characterized the alpha thalassemia determinants among Kuwaiti Arabs. PCR, hybridization and DNA sequencing techniques were used to analyze 64 alpha-thalassemia chromosomes. Three mutations were identified in 30 chromosomes from patients with HbH disease. These were: Poly A signal mutation in alpha 2-globin gene (86.7%), -alpha (3.7 Kb deletion; 10%), and alpha-5nt alpha (3.3%).