Objectives: To investigate the predictive accuracy
of using a combination of the high pressure liquid
chromatography (HPLC) retention time and the
relative isoelectric focusing (IEF) position to diagnose
rare hemoglobin variants.
Methods: A selected group of 40 patients with a
rare beta-chain variant were assigned a presumed
diagnosis following HPLC and IEF screening and
then the variant identified in each case by DNA
analysis. The study was conducted at the National
Hemoglobinopathy Reference Laboratory, Oxford,
United Kingdom, from August 2008 to October
2008.
Results: Thirteen out of 14 different variants were
predicted accurately in 39 (97.5%) cases, compared
to only one each for HPLC and IEF when used
individually. A novel amplification refractory
mutation system-polymerase chain reaction test was
developed for Hb J-Baltimore and used successfully,
to provide a simple, rapid, and inexpensive diagnosis.
Conclusion: The use of both HPLC retention time
and isoelectric focusing position provides an accurate
presumed diagnosis of a rare hemoglobin variant in the
majority of cases. Amplification refractory mutation
system-polymerase chain reaction test can provide a
simple, rapid and inexpensive molecular diagnostic
method for rare beta-chain variants.