Background: Hemoglobin H (Hb H) disease, a subtype of α-thalassemia, demonstrates marked clinical heterogeneity primarily driven by underlying genotypic differences. While non-deletional mutations are typically associated with more severe phenotypes, considerable variability is observed even among patients with similar mutation classes. This study aimed to examine genotype–phenotype correlations in Hb H disease by assessing the relationship between α-globin mutations, transfusion dependency, and a range of hematologic and biochemical markers.
Methods: Ninety patients with confirmed Hb H disease were evaluated. Genotyping was performed via multiplex gap-PCR, Sanger sequencing, and MLPA. Patients were classified by transfusion need into transfusion-dependent (TDT), occasionally transfused (OTDT), and non-transfusion-dependent (NTDT) groups. Genotypically, patients were categorized as non-deletional homozygotes (ND/ND), compound heterozygotes (ND/D), and deletional homozygotes (D/D). Complete blood count, hemoglobin fractions, iron profile, liver enzymes, and C-reactive protein (CRP) levels were measured and analyzed.
Results: Significant differences in hematologic and biochemical parameters were observed across genotypes. ND/ND patients had the highest hemoglobin (10.70 ± 1.83 g/dL), MCV (66.06 ± 8.43 fL), and HbA levels (93.72 ± 5.13%), and the lowest reticulocyte counts and Hb H percentages (p < 0.01). ND/D patients exhibited lower HbA, higher Hb H, and elevated ferritin (438.66 ± 840.60 ng/mL) and CRP (3.97 ± 4.75 mg/L) levels (p < 0.05), indicating greater erythropoietic stress. Transfusion dependence was most frequent in ND/D patients, though not statistically significant (p = 0.34).
Conclusion: This study highlights substantial phenotypic variability within genotypic groups, challenging the binary classification of deletional versus non-deletional mutations. Integrating molecular data with functional and inflammatory biomarkers may enhance risk stratification and support individualized management of Hb H disease.
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Original Article |
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Pediatric Hematology & Oncology Received: 2025/04/11 | Accepted: 2025/05/22 | Published: 2025/06/30