Molecular characterization of a high A2 beta thalassemia by direct
sequencing of single strand enriched amplified genomic DNA
SL Thein, C Hesketh, JM Brown, AV Anstey and DJ Weatherall
Nuffield Department of Clinical Medicine, John Radcliffe Hospital, Heading,
Oxford, UK.
Two families, one of Anglo-Saxon-Dutch descent, and the other, West Indian
black, have an atypical beta thalassemia characterized by an unusually high
level of Hb A2 in the heterozygous state. Restriction endonuclease mapping
showed a deletion of about 1.35 kilobase (kb) in the 5' region of the beta
globin gene. Direct sequencing of a specific region of genomic DNA
amplified by a new modification of the polymerase chain reaction defined
the deletion to be 1,393 base pairs (bp) and to be the same in both
families. The deletion extends from 485 bp 5' to the mRNA CAP site to the
middle of the second intervening sequence. This deletion, together with
three others previously described that remove the 5' end of the beta gene
but leave the delta gene intact, are all associated with unusually high
levels of Hb A2 in the heterozygous state.
Volume 73,
Issue 4,
pp. 924-930,
03/01/1989
Copyright © 1989 by The American Society of Hematology
