TYPE | Japanese (deltabeta)°-Thal (see Fig. 14) | ||
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CAUSE | A very large deletion including the psibeta, delta, and beta genes. The 5' breakpoint is located between 2134 and 2137 bp 3' to the poly A site of the Agamma gene, and the 3' breakpoint extending further than any other deletional mutant characterized thus far. | ||
DETECTION | Gene mappping with different probes and enzymes. The 5' breakpoint was analyzed by isolating a clone spanning the Japanese deltabeta-thal deletion junction. | ||
PHENOTYPE | Heterozygotes have a slight anemia and morphologic changes compatible with a mild thalassemia. Hb F is distributed unevenly in the RBCs. Hematological data: Hb 12.8 g/dl; RBC 6.04 x 1012/l; MCV 67 fl; MCH 21.2 pg; MCHC 31.7 g/dl; reticulocytes 1.0%; AgammaT 50.7%; Ggamma 49.3%; Hb A2 2.9%; Hb F 7.8%; non-alpha/alpha ratio 0.72. Homozygotes have a thalassemia intermedia-like condition. The deletion was first described in a 30-year-old Japanese woman who had moderate microcytosis and hypochromia with the following hematology: Hb 12 g/dl; RBC 4.85 x 1012/l; MCV 76 fl; MCH 24.7 pg; MCHC 32.6 g/dl; reticulocytes 2.4%; AgammaT 38.9%; Ggamma 61.1%; Hb A2 0%; Hb F 100.0%; non-alpha/alpha ratio 0.44. The blood film showed moderate anisocytosis and poikilocytosis. The chromosome with this deltabeta-thal deletion carries the ATA->ACA mutation at codon 75 (Ile->Thr; Agamma). | ||
DISTRIBUTION | Found in Japanese families. |
REFERENCES | |||
1. | Matsunaga, E., Kimura, A., Yamada, H., Fukumaki, Y., and Takagi, Y.: Biochem. Biophys. Res. Commun., 126:185, 1985. | ||
2. | Shiokawa, S., Yamada, H., Takihara, Y., Matsunaga, E., Ohba, Y., Yamamoto, K., and Fukumaki, Y.: Blood, 72:1771, 1988. |