Open AccessHb I: A α‐globin chain variant causing unexpected HbA 1c results
Author(s) -
Xu Anping,
Sun Jian,
Li Jie,
Chen Weidong,
Zheng Ruoyang,
Han Zhonghou,
Ji Ling
Publication year - 2019
Publication title -
journal of clinical laboratory analysis
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.536
H-Index - 50
eISSN - 1098-2825
pISSN - 0887-8013
DOI - 10.1002/jcla.22671
Subject(s) - hemoglobin variants , glycemic , transversion , hemoglobin , sanger sequencing , capillary electrophoresis , medicine , hemoglobin a , microbiology and biotechnology , gastroenterology , chemistry , chromatography , mutation , insulin , gene , biology , biochemistry
Background HbA 1c is the standard bio‐marker for glycemic control in patients with diabetes. Here, we report a α‐globin chain variant and evaluate its effect on HbA 1c measurements. Methods A 21‐year‐old female was suspected of harboring a hemoglobin variant following HbA 1c measurement during a routine examination using Variant II Turbo 2.0 (Bio‐Rad). An oral glucose tolerance test was performed using an AU 5800 clinical chemistry system (Beckman Coulter). HbA 1c was reanalyzed using D10 (Bio‐Rad), Capillarys 2 Flex Piercing (Sebia), and Premier Hb9210 (Trinity Biotech). Hemoglobin analysis was performed using high‐performance liquid chromatography ( HPLC ) on the Bio‐Rad Variant II (β‐thalassemia short program) and capillary electrophoresis ( CE , Capillarys 2 Flex Piercing, Hb program). Sanger sequencing of α and β genes was also conducted. Results HbA 1c was initially measured at 24.2% using Variant II Turbo 2.0. For the oral glucose tolerance test, fasting glucose, 1‐hour, and 2‐hour levels were recorded as 4.25, 7.89, and 5.34 mmol/L, respectively. Subsequently, HbA 1c values determined by D10, Capillarys 2 Flex Piercing (HbA 1c program), and Premier Hb9210 were 4.5% (26 mmol/mol), no HbA 1c value, and 4.8 (29 mmol/mol), respectively. Hemoglobin analyzed using CE and HPLC revealed an abnormal hemoglobin. Sanger sequencing identified a transversion mutation of the α2 gene [ CD 16( AAG > GAG ), Lys>Glu, HBA 2 : c.49 A>G], corresponding to a Hb I variant. Conclusion An unusually high HbA 1c or discordance between blood sugar and HbA 1c values should alert about the possibilities of hemoglobin variants.