Objective: To analyze the genotype-phenotype correlations in the Hb Constant Spring (HbCS) carriers, and to investigate the effect of HbCS on hematologic parameters.
Methods: Complete blood cell count and hemoglobin electrophoresis analyses were performed in 125 HbCS cases. The α-and β-thalassemia mutations were determined by reverse dot-blotting and Gap-PCR.
Results: The presence of the SEA deletion or Hb Quong Sze (HbQS) with HbCS leads to HbH-CS disease. There was significant difference between HbH-CS and αCSα/-α, HbH-CS and αCSα/αα in the hematological parameters. The genotype of αCSα/-α or αα/αCSα had slight effect on hematological parameters. When the Hb Constant Spring mutation co-existed with heterozygous β-thalassemia, the hematological characteristics of β-thalassemia was presented. Only 57.6% of carriers with HbCS were detected by hemoglobin electrophoresis.
Conclusion: The cases with co-existence of HbCS trait and other α-thalassemia trait, or β-thalassemia trait, showed variation in their red blood cell parameters. For such compound heterozygotes for HbCS and other α- or β-thalassaemia mutations, which were usually misdiagnosed in clinical screening by hemoglobin electrophoresis, accurate diagnose can be made by molecular diagnosis.