Abstract
We report a second occurrence of hemoglobin (Hb) Tyne, [β5 (A2) Pro>Ser] HBB:c.16C>T(p.Pro6Ser), which like the first case was associated with normal hematology. We verified the variant was mildly unstable by showing it was greatly enriched in isopropanol precipitates. This minor instability accounts for the slightly decreased expression of the new β chain. The variant was picked up as an interfering component on HbA1c testing using cation exchange high performance liquid chromatography (HPLC). However, this may be an advantage in detecting electrophoretically silent variants. Furthermore, this report also highlights the importance of uneven or sloping baselines on HPLC, which could reflect the presence of a variant hemoglobin even in the presence of normal electrophoresis and full blood count.
Highlights
Two further cases are described in a Caucasian mother and daughter, aged 75 and 52 respectively
This report e highlights the importance of uneven or sloping baselines on high performance liquid chroia matography (HPLC), which could m reflect the presence of a variant hemoglobin even in the presence of normal elecm trophoresis and full blood count
Ion-exchange HPLC separates hemoglobin including HbA1c and Hb glycated at other sites and so it tends to demonstrate the least interference from the presence of hemoglobin variants and derivatives.[2]
Summary
Two further cases are described in a Caucasian mother and daughter, aged 75 and 52 respectively. We verified the variant was mildly o unstable by showing it was greatly enriched in isopropanol precipitates This minor e instability accounts for the slightly s decreased expression of the new β chain. A Bio-Rad D10 (Hercules, California, USA) instrument, column and reagents and the HbA2/F extended programme This showed an unusual sloping baseline (Figure 1A) with no other remarkable features. The new β chain represented 42% of the total β material and this low expression level appears to be due to intrinsic instability, because when a standard isopropanol test was extended to 40 min and the light precipitate that formed n co Introduction o There has been only one previous report N of Hb Tyne where it was identified in two unrelated diabetic males.[1] There was no obvious hematological abnormality associated with either case and full blood counts were normal. Both cases were heterozygous and had approximately 37% Hb Tyne
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