HB TROLLHATTAN [BETA-20(B2)VAL-]GLU] - HEMOGLOBIN-VARIANT WITH INCREASED OXYGEN-AFFINITY CAUSING ERYTHROCYTOSIS

Erythrocytosis is sometimes caused by the presence of haemoglobin (Hb) variants with increased oxygen affinity. Here we describe a beta-glob in variant found by isoelectric focusing (IEF) of Hb from a 23-year-ol d Swedish male with moderate erythrocytosis. Amplification of DNA corr esponding to the beta-globin gene and subsequent nucleotide sequencing revealed heterozygosity for a GTG --> GAG mutation at codon 20, thus suggesting a Val --> Glu substitution, which was confirmed at the prot ein level. This mutation occurs at the same position as Hb Olympia [be ta 20(b2)Val --> Met], another variant associated with erythrocytosis due to increased oxygen affinity. The novel variant, Hb Trollhattan [b eta 20(B2)Val --> Glu], which was also associated with increased oxyge n affinity, was shown to be present in three generations of the patien t's family.