Rare Hemoglobin Variant Hb Yaizu Observed in Turkey

OBJECTIVE: To determine the characteristic features of the rare hemoglobin (Hb) variant Hb Yaizu to enable laboratory diagnosis of the hemoglobin variants during screening programs. MATERIALS AND METHODS: Genomic DNA was obtained from the 4 members of a family living in Denizli province, an Aegean region of Turkey. Blood cell counts, hemoglobin composition, hemoglobin electrophoresis (both alkaline and acid), HPLC analysis, DNA sequencing and beta globin gene cluster haplotypes were done. RESULTS: Hb Yaizu carriers were apparently healthy individuals. Hb Yaizu was slightly faster than Hb S at alkaline pH, but slower than Hb S at acidic pH in hemoglobin electrophoresis. An abnormal hemoglobin peak was observed with a retention time of 4.77 min in HPLC analysis attributed to Hb Yaizu. Two members of the family were heterozygous Hb Yaizu [beta 79(EF3) Asp>Asn] confirmed by DNA sequencing. The mutation was found to be linked with the Mediterranean haplotype I [+----++]. CONCLUSION: We have presented the details of Hb Yaizu, a rare hemoglobin variant that may be important to hemoglobinopathy screening programs, although its clinical significance is unclear.