Two rare mutations [CD 30 (G-->C) and CDs 36/37 (-T)] in a Turkish thalassemia major patient from Bulgaria

A rare mutation [IVS-I-130 (G-A)] in a Turkish beta-thalassemia major patient

Here we describe the identification of the rare beta-thalassemia mutation IVS-I-130 (G-A) for the first time in Turkey. The hematological evaluation of the patient showed classical signs of beta-thalassemia major requiring regular blood transfusions every 30-35 days. DNA analysis was carried out using reverse dot-blot hybridization and restriction endonuclease digestion, as well as genomic sequencing. The patient was found to be heterozygous for the IVS-I-6 (T-C) and IVS-I-130 (G-A) mutations. In order to deduce a possible origin for the IVS-I-130 (G-A) mutation, the sequence polymorphisms in the DNA of the patient and her family were characterized. The method included the analysis of nine polymorphic nucleotides and the hypervariable microsatellite of composite sequence (AT)(x)T(y) 5' to the beta-globin gene by DNA sequencing. The sequence haplotype (HT4) carrying the IVS-I-130 (G-A) mutation is also observed in Algeria. This favors a Northeastern African origin for this allele. The observed results agree well with a recent introduction of this mutation to Turkey from Egypt toward the end of the 19th century.

A significant beta-thalassemia heterogeneity in the United Arab Emirates

The Dubai Thalassemia Center has identified 35 different beta-thalassemia mutations in 570 chromosomes from the United Arab Emirates population using gene amplification, hybridization with specific labeled oligonucleotide probes, sequencing of amplified DNA, restriction enzymes, and amplification refractory mutation system techniques. This large number of mutations which represent 21% of the total beta-mutations discovered worldwide reflects the heterogenous nature of the population living in the United Arab Emirates (1). We found that 50% of our beta-thalassemia patients have a concomitant alpha-thalassemia; namely the -alpha 3.7 kb deletion. Co-inheritance of alpha-thalassemia especially in the form of two alpha-globin gene deletions have an ameliorating effect on the phenotype presentation of our beta-thalassemia. Nine patients (one homozygote and eight compound heterozygotes) were identified with Hb Monroe (IVS-I,-1 (G-->C)), a thalassemic hemoglobin characterized by an Arg-->Thr substitution in codon 30 of the beta-globin gene. In addition, one of the patients was a compound heterozygote for Hb Tacoma [IVS-I, +1 (G-->C)]; a point mutation affecting the third nucleotide of codon 30 (G-->C) causing an Arg-->Ser replacement.

Hb F-Macedonia-II [G gamma 104(G6)Lys-->Asn]: a new gamma chain variant

In the course of our newborn screening program for the presence of hemoglobinopathies in the Republic of Macedonia, we have detected a new G gamma chain variant with a Lys-->Asn or AAG-->AAC substitution at codon 104. The variant was found in a blood sample from a healthy baby boy of Macedonian nationality. The abnormal chain was quantitated at 32.4% of the total gamma chains by reversed phase high performance liquid chromatography. The characterization of the variant was by sequence analysis of polymerase chain reaction-amplified DNA. The presence of the mutation in the mother was confirmed by Hph I restriction enzyme digestion of the polymerase chain reaction-amplified DNA fragment. Although the mutated G is the last nucleotide of exon 2 and part of the donor splice site sequence of the second intervening sequence of the G gamma gene, it appears that the splicing of the mRNA in this variant is not altered.