First Detection of Hb Taybe [α38(C3) or α39(C4) Thr→0 (α1)] in An Italian Child

A combination of two novel alpha globin variants Hb Bridlington (HBA1) and Hb Taybe (HBA2) resulting in severe hemolysis, pulmonary hypertension, and death

OBJECTIVE AND IMPORTANCE

To describe two novel hemoglobin mutations that resulted in an unstable hemoglobin with a severe hemolytic phenotype.

CLINICAL PRESENTATION

A patient with an unstable hemoglobin and chronic hemolysis underwent splenectomy at age 15, subsequently developing chronic thrombo-embolic pulmonary hypertension at age 27 that was ultimately fatal.

INTERVENTION

DNA sequencing of the alpha globin gene revealed heterozygous inheritance of Hb Taybe, arising from a novel mutation in the HBA2 gene and Hb Bridlington, a novel HBA1 mutation. Greater disease severity is predicted by the position of the Hb Taybe mutation on the HBA2 gene (which transcribes more globin than the HBA1 gene).

CONCLUSION

Splenectomy was not clearly beneficial and may have contributed to the development of pulmonary hypertension. The case favors a cautious approach when considering splenectomy for patients with Hb Taybe.

Thrombosis in Hb Taybe [codons 38/39 (-ACC) (α1)]

Hb Taybe is a highly unstable hemoglobin (Hb) variant caused by a 3 bp deletion at codons 38/39 (-ACC) on the α1-globin gene. We report for the first time, a patient with a compound heterozygosity for Hb Taybe and a 5 bp deletion at the splice donor site of IVS-I on the α2-globin gene and ischemic stroke and priapism. The patient, a male of Palestinian origin, suffered since childhood from moderate hemolytic anemia. Splenectomy was performed at the age of 19. Five years after the splenectomy, recurring attacks of priapism occurred and at the age of 28 the patient had a pontine infarction. A heterozygote prothrombin G20210A mutation was found. We assume that ongoing intravascular hemolysis, splenectomy and the prothrombin G20210A mutation may explain the thrombotic tendency in this case.