TYPE | Dutch (epsilongammadeltabeta)°-Thal (see Fig. 17) | ||
---|---|---|---|
CAUSE | The deletion removes 99.4 kb DNA extending from 2.5 kb upstream from the beta gene to ~57 kb 5' to the epsilon gene. The beta gene and its flanking sequences are intact, while the epsilon, gamma, and delta genes are deleted. | ||
DETECTION | It was initially thought that this condition could be the caused by a point mutation or a small deletion in the beta gene. This was eliminated by sequencing the entire beta gene. Gene mapping with different enzymes and probes. | ||
PHENOTYPE | The subjects have the hematological characteristics of a heterozygous beta°-thal, except for normal Hb A2 values. Hematological data are as follows: Hb 9.7 g/dl; RBC 4.5 x 1012/l; MCV 67 fl; Hb A2 3.2%; Hb F 1.0%; alpha/beta ratio 2.0. During postnatal development a chronic microcytic anemia persists in the carriers, with normal or near normal reticulocyte counts and bilirubin levels. | ||
DISTRIBUTION | Found in seven members of a Dutch family from The Netherlands. |
REFERENCES | |||
1. | Van der Ploeg, L.H.T., Konings, A., Oort, M., Roos, D., Bernini, L., and Flavell, R.A.: Nature, 283:637, 1980. |