MUTATION | - -(THAI); a deletion of 34-38 kb involving the alpha1, alpha2, and zeta genes (see Fig. 24) | ||
---|---|---|---|
AMINO ACID REPLACEMENT | None | ||
TYPE OF ALPHA-THAL | alpha-Thal-1 [- -/] | ||
MECHANISM | Absence of the alpha2-, alpha1-, and zeta-globin genes result in no synthesis of alpha-, beta-, or zeta-mRNAs | ||
IDENTIFICATION | Gene mapping | ||
HEMATOLOGY IN HETEROZYGOTE(S) | Microcytosis; hypochromia | ||
HEMATOLOGY IN HOMOZYGOTE(S) | Fetuses with a homozygosity for this deletion (hydrops fetalis) are usually aborted because of the complete absence of zeta chain synthesis | ||
OCCURRENCE | In Southeast Asian families (Thailand) | ||
HAPLOTYPE | Not determined | ||
FOUND IN COMBINATION WITH ABNORMAL HB(S) | Not reported | ||
FOUND IN COMBINATION WITH alpha-THAL ALLELE(S) | Found in a few patients with Hb H disease [-alpha(3.7) or -alpha(CS)]: Hb ~10 g/dl; MCV 60-65 fl; MCH 20-24 pg; Hb H 15-20% | ||
OTHER INFORMATION | None |
REFERENCES | |||
1. | Fischel-Ghodsian, N., Vickers, M.A., Seip, M., Winichagoon, P., and Higgs, D.R.: Br. Haematol., 70: 233, 1988. |