IthaID: 1512

We follow the HGVS sequence variant nomenclature and IUPAC standards.

Comments: The Laotian (δβ)0 thalassaemia deletion is approximately 12.5 kb in length with similar breakpoints to the Thai/Vietnamese (δβ)0 [ithaID=1513] deletion. The 5' breakpoint lies in the IVS-II of the δ-globin gene, localised 18 to 24 bp downstream of the Thai/Vietnamese breakpoint. The 3' breakpoint lies in an L1 repeat sequence between two PstI sites 4.7 kb 3’ of the β-globin gene, which is approximately 0.7 kb upstream from the Sicilian deletion breakpoint [ithaID=1507] similar to the Thai/Vietnamese deletion. The deletion breakpoints were localised by resctriction endonuclease mapping. Therefore, in the absence of breakpoint sequence information and given that the breakpoints lie in regions (AT-rich region-Alu and the L1 repeats) with propensity for higher recombination rate, there exists a possibility that the two deletions are different. The Laotian (δβ)0 thalassaemia deletion was found in a heterozygous state in a Laotian man with mild anaemia and elevated HbF (11.5%) with heterocellular distribution.

Heterozygous records (preview in IthaPhen)

1. Zhang JW, Stamatoyannopoulos G, Anagnou NP, Laotian (delta beta) (0)-thalassemia: molecular characterization of a novel deletion associated with increased production of fetal hemoglobin., Blood, 72(3), 983-8, 1988
2. Craig JE, Barnetson RA, Prior J, Raven JL, Thein SL, Rapid detection of deletions causing delta beta thalassemia and hereditary persistence of fetal hemoglobin by enzymatic amplification., Blood, 83(6), 1673-82, 1994
3. Tritipsombut J, Phylipsen M, Viprakasit V, Chalaow N, Sanchaisuriya K, Giordano PC, Fucharoen S, Harteveld CL, A single-tube multiplex gap-polymerase chain reaction for the detection of eight β-globin gene cluster deletions common in Southeast Asia., Hemoglobin, 36(6), 571-80, 2012