We studied a fast-moving, abnormal hemoglobin (Hb) identified as Fannin-Lubbock-I [beta119(GH2)Gly-->Asp] in a homozygous Mexican girl. To date, homozygosity for the Hb Fannin-Lubbock-I variant has not been reported. Her parents and five other relatives were heterozygotes. The 5' beta-globin haplotype analysis showed that the mutation was associated with haplotype 2 [- + + - +]for the epsilon, (G)gamma, (A)gamma, 5' and 3 'psibeta-globin sites, and also segregated with the TGTTC haplotype, which was constructed with five polymorphic sites of the beta-globin gene [exon 1-nucleotide (nt) 6 (C>T) and IVS-II-16 (C>G), IVS-II-46 (T>C), IVS-II-74 (G>T), and IVS-II-81 (C>T). In 1994, a variant with an additional mutation at codon 111 [beta111(G13)Val-->Leu] was described in five Spanish families. This variant was termed Hb Fannin-Lubbock-II, and the question of the existence of Hb Fannin-Lubbock-I arose. However, based on our findings, we were able to confirm the existence of Hb Fannin-Lubbock-I and propose that this mutation has a different origin from the one identified in Spanish families.