Human fetal globin DNA sequences suggest novel conversion event

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Abstract
DNA sequencing studies of two recently cloned human Aγ globln alleles has revealed a number of base differences which are clustered in the large intron (IVS-2). One allele has a previously undescribed IVS-2 sequence. Most of the allelic differences can be explained as resulting from a gene conversion event involving Gγ as a donor. A novel feature of this event is that three Cγ-Hke regions occur interspersed among unconverted areas of the Aγ gene. We propose that an alternating purine-pyrimidine run which is located between two of the converted sites is the initiation site of the conversion event. Consistent with models of gene conversion, this poly (purine-pyrimidine) tract has single-stranded characteristics in supercoiled plasmids as assayed by S1-nuclease.