| MUTATION | Codons 38/39 [-ACC (Thr)]; deleted from the alpha1-globin gene | ||
|---|---|---|---|
| AMINO ACID REPLACEMENT | Deletion of a threonine residue at position alpha38 or alpha39 (Hb Taybe) | ||
| TYPE OF ALPHA-THAL | alpha-Thal-2 [alphaalpha(T)/alphaalpha] | ||
| MECHANISM | The instability of the abnormal Hb results in a decrease in alpha chain synthesis | ||
| IDENTIFICATION | Amplification; DNA sequencing | ||
| HEMATOLOGY IN HETEROZYGOTE(S) | Hb 9.3-14.7 g/dl; MCV 69-85 fl; MCH 21-29 pg; Hb A2 and Hb F normal | ||
| HEMATOLOGY IN HOMOZYGOTE(S) | Hb 7.3 g/dl; RBC 2.1 x 1012/l; PCV 0.244 l/l; MCV 117 fl; MCH 35 pg; reticulocytes 530 x 109/l (Ref. 1); severe hemolytic disease | ||
| OCCURRENCE | In a few Arabian families living in Israel | ||
| HAPLOTYPE | Not determined | ||
| FOUND IN COMBINATION WITH ABNORMAL HB(S) | Not reported | ||
| FOUND IN COMBINATION WITH | A poly A mutation in trans (alpha2; AATAAA->AATAAG; Ref. 2) resulting in severe hemolytic disease: Hb 8.5 g/dl; MCV 117.7 fl; reticulocytosis and folic acid deficiency; MCV 28.7 fl; Hb A2 1.3%. Blood transfusions are required; patient was splenectomized; Hb H was not detected but might be present in low quantities | ||
| OTHER INFORMATION | The abnormal Hb can be detected by IEF; amount in the compound heterozygote estimated at ~5%; heat stability test on freshly collected sample was positive; structural analyses have confirmed the loss of a threonine residue |
| REFERENCES | |||
| 1. | Galacteros, F., Girodon, E., M'Rad, A., Martin, J., Goossens, M., Jaber, L., Cohen, I.J., Tamar, H., Goshen, Y., Zaizov, R., and Wajcman, H.: C.R. Acad. Sci., 317:437, 1994. | ||
| 2. | Pobedimskaya, D.D., Molchanova, T.P., Streichman, S., and Huisman, T.H.J.: Am. J. Hematol., 47: 198, 1994. | ||