title: A spurious haemoglobin A(1c) result associated with double heterozygote for haemoglobin Raleigh (β1[NA1]Val → Ala) and α(+)-thalassaemia.
abstract: BACKGROUND
  Accurate measurement of haemoglobin A(1c) (HbA(1c)) is useful for long-term glycaemic control in patients with diabetes. Many Hb variants can interfere with HbA(1c) measurement and cause inaccurate results.
  
  
  METHODS
  The subject was a 31-year-old Thai man who was discovered because of an unexpected HbA(1c) result; other diabetic parameters were within the normal range. Abnormal Hb was investigated using automated high-pressure liquid chromatography (HPLC) and a capillary electrophoresis system. Mutation analysis was done by cDNA sequencing, polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) and multiplex allele-specific PCR assays.
  
  
  RESULTS
  Evaluation of HbA(1c) by cation-exchange HPLC showed a value of 34.9% (reference interval, 4.0-6.0%), but a value of only 4.0% (reference value, 4.8-5.9%) was found with a turbidimetric immunoassay. Haematological analysis revealed a mild anaemia but other parameters were within the normal range. Hb-HPLC analysis demonstrated an unknown Hb variant (47.0%) separating from HbA (46.7%), but capillary electrophoresis identified no abnormal peaks. Mutation analysis identified the Hb Raleigh (β1[NA1]Val → Ala [GTG → GCG]) mutation in combination with an α(+)-thalassaemia, a hitherto undescribed association. The Hb Raleigh mutation could be detected by PCR-RFLP or a multiplex allele-specific PCR assay.
  
  
  CONCLUSIONS
  Hb Raleigh can cause falsely increased HbA(1c) values on cation-exchange HPLC. Definitive diagnosis of this variant using combined Hb and DNA analyses is therefore essential.
authors: The Graduate School, Khon Kaen University, Khon Kaen 40002, Thailand.
authors: Kritsada
authors: K
authors: Singha
authors: Goonnapa
authors: G
authors: Fucharoen
authors: Attawut
authors: A
authors: Chaibunruang
authors: Paripat
authors: P
authors: Netnee
authors: Supan
authors: S
authors: Fucharoen
mesh_terms: D000328:Adult; D044466:Asian People; D001483:Base Sequence; D002411:Cation Exchange Resins / Q000737:chemistry; D002851:Chromatography, High Pressure Liquid; D004252:DNA Mutational Analysis; D003937:Diagnosis, Differential; D014644:Genetic Variation; D006442:Glycated Hemoglobin / Q000737:chemistry* / Q000235:genetics; D006455:Hemoglobins, Abnormal / Q000737:chemistry / Q000235:genetics*; D006579:Heterozygote; D006801:Humans; D008297:Male; D008969:Molecular Sequence Data; D017085:alpha-Thalassemia / Q000235:genetics*
chemical_list: D002411:Cation Exchange Resins; D006442:Glycated Hemoglobin; D006455:Hemoglobins, Abnormal; C083887:hemoglobin Raleigh