Genetics and Molecular Biology
Print version ISSN 1415-4757
SUN, Yanbo et al. Familial congenital cyanosis caused by Hb-MYantai (α-76 GAC → TAC, Asp → Tyr). Genet. Mol. Biol. [online]. 2010, vol.33, n.3, pp. 445-448. Epub June 25, 2010. ISSN 1415-4757. http://dx.doi.org/10.1590/S1415-47572010005000058.
Methemoglobin (Hb-M) is a rare hemoglobinopathy in China. We hereby report on a family living in Yantai, East China, with congenital cyanosis due to Hb-M mutation. The proband, a 65-year-old female, presented 63% oxygen saturation. Both Hb-M concentration and arterial oxygen saturation remained unchanged, even following intravenous treatment with methylene blue. There was also no change in blood-color (chocolate-brown) after adding 0.1% KCN. A fast-moving band (Hb-X) in hemolysates was found by cellulose acetate electrophoresis, the Hb-X/Hb-A ratio exceeding 10%. GT transition at 131nt of exon 2, although present in one of the α2-globin alleles, was not found in α1-globin alleles as a whole. This mutation leads to the aspartic acid to tyrosine substitution (Asp76Tyr). In this family, the novel mutation in the α2-globin gene resulted in a rare form of congenital cyanosis due to Hb-M. This hemoglobin was named Hb-MYantai.
Keywords : congenital cyanosis; hemoglobin; methemoglobinemia; a-globin gene; China.