RESUMO
Hereditary persistence of fetal hemoglobin (HPFH) can be caused by point mutations in the γ-globin gene promoters. We report three rare cases: a child compound heterozygous for Hb S (HBB: c.20A > T) and HPFH with a novel point mutation in the (A)γ-globin gene promoter who had 42.0% Hb S, 17.0% Hb A and 38.0% Hb F; a man with Hb SC (HBB: c.19G > A) disease and a point mutation in the (G)γ-globin gene promoter who had 54.0% Hb S, 18.0% Hb C and 25.0% Hb F; a child heterozygous for Hb S and HPFH due to mutations in both the (A)γ- and (G)γ-globin gene promoters in cis [(G)γ(A)γ(ß(+)) HPFH], with 67.0% Hb A, 6.5% Hb S and 25.0% Hb F.
Assuntos
Hemoglobina Fetal/genética , Doença da Hemoglobina SC/genética , Hemoglobina Falciforme/genética , Mutação Puntual , Traço Falciforme/genética , gama-Globinas/genética , Adulto , Feminino , Hemoglobina C/genética , Heterozigoto , Humanos , Lactente , Masculino , Regiões Promotoras GenéticasRESUMO
Hb Kenya is a hemoglobin (Hb) tetramer composed of two normal α- and two non α-globin chains. The latter are the product of a fusion gene in which the 5' end is (A)γ and the 3' end is ß. The crossover point is between codon 81 of the (A)γ gene and codon 86 of the ß gene. Like the other non α genes, the hybrid protein product ((A)γ81Leu-ß86Ala) has 146 amino acids. The purpose of this report is to highlight the laboratory findings of Hb Kenya and to emphasize the pitfalls in misdiagnosis, particularly when associated with another variant such as Hb S [ß6(A3)GluâVal].
