Genomic DNA from two Brazilian hemoglobin (Hb) Lepore heterozygotes of Italian ancestry have been studied in order to identify the Hb Lepore type and to sequence the breakpoint region. The two genes were sequenced after PCR amplification and had the δ globin sequence up to exon 2 codon 68 while the first specific base for the β globin gene was at codon 86 of the second exon; between the two ends, they had 51 base pairs in common with the δ and β globin genes. These data indicate that the mutation was of the Hb LeporeBaltimore type. The Lepore chromosome haplotype was different from that previously described in members of a Spanish family with Hb LeporeBaltimore. These data suggest that independent mutations have given rise to Hb LeporeBaltimore in different regions of the wo