The increase of Hb A(2) (α2δ2) beyond the upper limit [2.0-2.2/3.3-3.4% of the total hemoglobin (Hb)] is an invaluable tool in the hematological screening of β-thalassemia (β-thal) carriers. Factors decreasing Hb A(2) percentages can hinder correct diagnosis. In order to analyze the genotype-phenotype relationship, we characterized δ-, β- and α-globin genotypes in 190 families where the probands had Hb A(2) values of ≤2.0% or were β-thal heterozygotes with normal Hb A(2) levels. Hb A(2) was measured with cation exchange high performance liquid chromatography (HPLC). Mutations were detected with allele-specific methods or DNA sequencing; two multiplex-ARMS (amplification refractory mutation system) assays were set up. The molecular basis underlying the decrease in Hb A(2) was extremely heterogeneous. Nineteen δ-globin alleles (Hb A(2)-S.N. Garganico was new) were detected; their interaction with α- or β-globin alleles (10 and eight, respectively) led us to observe 52 genotypes in 261 carriers. The type of δ-globin mutations, the relative genotypes, the interaction with α(0)-thal traits, are the most important factors in decreasing the Hb A(2) percentage. These results are extremely useful in addressing the molecular diagnosis of hemoglobinopathies and thalassemias.

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The study of the alleles of the delta-globin gene is relevant to the prevention of beta-thalassemia homozygosis; in fact, the increase of the HbA2 is an invaluable hematological marker of the beta-thalassemia heterozygosis and the double heterozygosis for alleles of delta- and beta-globin genes can cause the decrease of the HbA2 up to normal or borderline values. We carried out the characterization of alleles of the delta- and beta-globin genes, restriction fragment length polymorphism (RFLP) haplotype background, and hematologic phenotype in 23 double heterozygotes belonging to 18 unrelated families. A wide heterogeneity of the delta-globin alleles was detected; seven known alleles in trans to the beta-globin gene defects were revealed in 17 out of 18 families, while a new allele in cis to a beta-thalassemia allele was detected in one family. Moreover, the relative frequency of the delta-mutants was quite different from that found among heterozygotes. The new allele delta-cod 5 CCT>ACT, in cis to the allele beta(+) thal IVS-I-110 G>A, was found in five carriers of a Sicilian family. The new variant delta5(A2)Pro-->Thr, named HbA2-Partinico upon the origin of the family, was detected with high-performance liquid chromatography; it overlapped the HbA2 peak which was partially split. The double in cis heterozygotes had increased percentage of normal and variant HbA2 of comparable size. The variant originated most likely from a new mutational event because it was associated with RFLP haplotype I, commonly found with the beta(+) thal IVS-I-110 G>A, even if crossing over or gene conversion cannot be excluded.

We identified two unstable variants in the third exon of α-globin genes: Hb Bernalda/Groene Hart (HBA1:c.358C>T), and Hb Caserta (HBA2:c.79G>A) in cis to Hb Sun Prairie (HBA2:c.391G>C), also named Hb Southern Italy. These mutations occurred in the H helix of the α-globin that is involved in heme contacting, specific recognition of α-hemoglobin-stabilizing protein (AHSP), and α1β1 interactions. The carriers showed α-thalassemia phenotype, but one also jaundice and cholelithiasis. Molecular identification of clusters of families in Southern Italy encouraged molecular characterization of mRNA, globin chain analyses, molecular modeling studies, and comparison with globin variants to understand the mechanisms causing the α-thalassemia phenotype. A normal amount of Hb Bernalda/Groene Hart mRNA were found, and molecular modeling highlighted additional H bonds with AHSP. For Hb Southern Italy, showing an unexpected α/β biosynthetic ratio typical of the β-thalassemia type, two different molecular mechanisms were shown: Reduction of the variant mRNA, likely due to the No-Go Decay for the presence of unused triplet ACG at cod 26, and protein instability due to the impairment of AHSP interaction. The UDP glucuronosyltransferase 1A (UGT1A1) genotyping was conclusive in the case of jaundice and cholelithiasis. Multiple approaches are needed to properly identify the mechanisms leading to unstable variants and the effect of a mutation.

Three short-term randomised clinical trials suggested not difference of Deferiprone (L1) vs Deferoxamine (DFO) in term of iron overload efficacy in thalassemia major (TM) patients. To assess whether L1 (75mg/Kg) alone was comparable to a sequential treatment using L1 (75mg/Kg) for 4 days and DFO (50mg/Kg) for 3 days, we carried ahead a large long-term randomised clinical trial. One-hundred and forty consecutive patients with TM and serum ferritin between 1,500 and 3,000 ng/ml were randomly assigned to L1 (n°69) or sequential L1-DFO (n°71) and treated for 5 years. The main measure of efficacy was the reduction of serum ferritin levels. Secondary outcomes were liver and heart iron contents assessed by T2* magnetic resonance. After one year-treatment the mean serum feritin reduction was −105 ± 90.4 in L1 and −409 ± 64.2 in sequential L1-DFO treatment (p <0.01), respectively. The greater mean serum ferritin reduction of sequential L1- DFO treatment was also confirmed all over the study (2° year L1 106 ± 713, L1-DFO -321 ± 92 (p <0.01); 3° year L1 137 ± 137, L1-DFO -292 ± 117 (p <0.05); 4° year L1 216 ± 200, L1-DFO-230 ± 170 (p <0.01); 5° year L1 336 ± 244, L1-DFO -598 ± 203 (p <0.01)). After one-year treatment this sequential group showed greater efficacy in term of serum ferritin levels reduction (−409 ± 64.2) in comparison with the DFO alone arm (−232 ± 619) of a previous randomised multicenter clinical trial in which a comparable cohort of patients were studied (p<0.05). Reversible leukocytopenia was shown in 8 (11.5%) L1 and in 7 (9.8%) sequential L1-DFO treated patients. No agranulocythosis was reported on sequential L1-DFO treated patients during the 5 years study. Hypertransaminasemia developed in 13 (18.8%) L1 and in 5 (7%) sequential L1-DFO treated patients. No other major side effects have been reported. Discontinuation of treatment was necessary in 55.6% L1 and in 57.7% sequential L1-DFO treated patients (chi2 0.03, p=0.86). The failures of treatment were less in sequential L1-DFO arm (n°2) in comparison to L1 alone arm (n°8), although this difference not so far reached the statistical significance (chi2 3.4, p=0.06). These findings suggest that sequential L1-DFO treatment in a long-term study is more effective than L1 alone with milder and reversible side effects. Moreover, its efficacy is also higher in comparison with DFO alone at short-term evaluation. Fig. 1 VARIATIONS OF THE FERRITIN LEVELS DURING FIVE YEARS TREATMENT BETWEEN THE TWO ARMS OF THE TRIAL Fig. 1. VARIATIONS OF THE FERRITIN LEVELS DURING FIVE YEARS TREATMENT BETWEEN THE TWO ARMS OF THE TRIAL