Table 2.
HBB mutations registered in the cohort of patients with transfusion-dependent β-thalassemia (TDT)
| Classical nomenclature | HGVS nomenclature | Allelic phenotype | Homozygous state | Heterozygous state | Total mutated alleles | Allele frequency (%) |
|---|---|---|---|---|---|---|
| Codon 39 (C > T) | HBB:c.118 > T | β0 | 10 | 14 | 34 | 31.2 |
| IVS-I-110 (G > A) | HBB:c.93-21G > A | β+ | 6 | 10 | 22 | 20.2 |
| IVS-I-1 (G > A) | HBB:c.92 + 1G > A | β0 | 4 | 5 | 13 | 11.9 |
| Codons 8/9 (+ G) | HBB:c.27_28insG | β0 | 3 | 1 | 7 | 6.4 |
| Codon 6 (-A) | HBB:c.20delA | β0 | 1 | 3 | 5 | 4.6 |
| Codon 5 (-CT) | HBB:c.17_18delCT | β0 | 1 | 3 | 5 | 4.6 |
| IVS-I-5 (G > C) | HBB:c.92 + 5G > C | β+ (severe) | 2 | 0 | 4 | 3.7 |
| IVS-I-6 (T > C) (Portuguese type) | HBB:c.92 + 6T > C | β+ | 1 | 2 | 4 | 3.7 |
| IVS-II-745 (C > G) | HBB:c.316-106 C > G | β+ | 0 | 4 | 4 | 3.7 |
| IVS-II-849 (A > C) | HBB:c.316-2 A > C | β0 | 1 | 0 | 2 | 1.8 |
| Codon 8 (-AA) | HBB:c.25_26delAA | β0 | 1 | 0 | 2 | 1.8 |
| IVS-I-2 (T > G) | HBB:c.92 + 2T > G | β0 | 0 | 2 | 2 | 1.8 |
| IVS-II-844 (C > G) | HBB:c.316-7 C > G | β+ | 0 | 1 | 1 | 0.9 |
| IVS-II-1 (G > A) | HBB:c.315 + 1G > A | β0 | 0 | 1 | 1 | 0.9 |
| Hb Monroe | HBB:c.92G > C | β0 | 0 | 1 | 1 | 0.9 |
| -28 (A > G) | HBB:c.-78 A > C | β+ | 0 | 1 | 1 | 0.9 |
| Codons 41/42 (-TTCT) | HBB:c.126_129delCTTT | β0 | 0 | 1 | 1 | 0.9 |
HGSV: Human Genome Variation Society.