Contrasting co-inheritance of alpha and beta mutations in delta beta thalassemia and hereditary persistence of fetal hemoglobin: a study from India

Abstract

Background and objectives: Coinheritance of δβ thalassemia and HPFH with inherited factors is sparsely documented and may affect treatment modalities. So, we screened the presence of α deletion and β mutations in δβ thalassemia and HPFH disorders in 52 cases with high Hb F concentration. Material and methods: Fifty-two individuals with raised HbF levels were study subjects. CZE was done for quantitative assessment of hemoglobin variants. Asian Indian inversion deletion break point type A, B and HPFH-3 were done by GAP-PCR. Results: 18/52 cases of δβ Gγ (Aγδβ)0 thalassemia and 28/52 cases of HPFH-3 deletion were characterized. 6/52 patients with raised HbF levels were negative for δβ Gγ (Aγδβ)0 and HPFH-3 deletion. 9/18 (50%) were heterozygous for Gγ(Aγδβ)0 break point type A, 6/18 (33%) were heterozygous for break point type B and 3/18 (17%) were homozygous. Of the nine patients heterozygous for Gγ(Aγδβ)0 break point type A, three (33%) patients were double heterozygous with alpha 3.7 kb deletion and two (22%) patients showed compound heterozygosity with IVS 1–5(G–C) mutation. 4/9 (45%) patients were Gγ(Aγδβ)0 heterozygous. Discussion and conclusion: We found 5/18(27.β) δβ-thalassemia cases with co-inherited alpha 3.7 deletion and 3/18 (16β) cases with IVS 1–5(G–C) mutation. Patients showed features of thalassemia intermedia phenotype among which those with co-inherited IVS 1–5(G–C) mutation showed severe phenotype as compared to those with co-inherited alpha 3.7 deletion. So, we highlight importance of genotyping of patients with δβ thalassemia or HPFH and coinheritance with inherited factors which plays crucial role in clinicopathological profile and setting up prenatal diagnostic protocol.