Hb F-Charlotte, Hb F-Sassari, Hb F-Waynesboro |
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IDENTIFICATION | These variants were discovered by reversed phase HPLC; no separation by electrophoretic or chromatographic procedures. The gammaX chain of each carrier eluted at the same position on a reversed phase column. The differences are the presence of an additional AgammaT variant in the babies with Hb F-Sassari and Hb F-Waynesboro. | |||||||||||||||||||||||||||
CHAIN SEPARATION |
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DNA ANALYSES | Extensive DNA sequencing analysis has shown the following: The three babies have a normal chromosome with a normal Ggamma gene and a normal Agamma gene. The Ggamma gene of the second chromosome of the Hb F-Charlotte baby is also normal, but that of the Hb F-Waynesboro baby is mutated at codon 75 (GgammaX with ATA->ACA or Ile->Thr). Thus, the total Ggamma level in the Hb F from the Hb F-Charlotte baby is normal at 72.5%, and that in the Hb F-Waynesboro baby is also normal [Ggamma (43.0%) + gammaX (29.2%) = 72.2%]. The sequences of the Agamma genes in both babies suggest a limited gene conversion by replacing a segment of the Agamma gene by that of a Ggamma gene, which makes the 3' end of the gene different from that of a normal Agamma gene. Both hybrid genes have an ATA->ACA mutation at codon 75 (Ile->Thr), while that in the Hb F-Charlotte baby has an additional GCA->GGA mutation at codon 136. The products of these hybrid genes will occupy different positions in the chromatogram.
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REFERENCES | |||
1. | Plaseska, D., Kutlar, F., Wilson, J.B., Fei, Y.J., and Huisman, T.H.J.: Hemoglobin, 14:617, 1980. | ||
2. | Ferranti, P., Barone, F., Pucci, P., Malorni, A., Marino, G., Pilo, G., Manca, L., and Masala, B.: Hemoglobin, 18:307, 1994. | ||
3. | Gu, L-H., Öner, C., and Huisman, T.H.J.: Hemoglobin, 19:413, 1995. |