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MUTATION | |
-(alpha)20.5; this 20.5 kb deletion involves the entire alpha2 and the 5' end of the alpha1 gene (see Fig. 24) | |
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AMINO ACID REPLACEMENT | |
None | |
TYPE OF ALPHA-THAL | |
alpha-Thal-1 [- -/] | |
MECHANISM | |
The deletion involves both alpha-globin genes; thus, no alpha-mRNAs are formed | |
IDENTIFICATION | |
Gene mapping; PCR methodology | |
HEMATOLOGY IN HETEROZYGOTE(S) | |
Hb 11-14 g/dl; MCV 65-72 fl; MCH 20-25 pg; Hb A2 2.0-2.5%; alpha/beta ratio 0.7-0.8 | |
HEMATOLOGY IN HOMOZYGOTE(S) | |
Hydrops fetalis | |
OCCURRENCE | |
In various Mediterranean and Central Asian populations | |
HAPLOTYPE | |
Not determined | |
FOUND IN COMBINATION WITH ABNORMAL HB(S) | |
Not reported | |
FOUND IN COMBINATION WITH alpha-THAL ALLELE(S) | |
Mainly the -alpha(3.7 kb) deletion; the 5 nt nondeletional alpha-thal-2, etc. causing Hb H disease: Hb 9.5-12.5 g/dl; MCV 63-77 fl; MCH 17-24 pg; Hb A2 0.6-1.0%; Hb H 10-20%; alpha/beta ratio 0.4-0.5 | |
OTHER INFORMATION | |
None | |
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REFERENCES |
1. | |
Nicholls, R.D., Higgs, D.R., Clegg, J.B., and Weatherall, D.J.: Blood, 65:1434, 1985. | |
2. | |
Bowden, D.K., Vickers, M.A., and Higgs, D.R.: Br. J. Haematol., 81:104, 1992. | |