SIX NEW ALPHA-THALASSEMIA MUTANTS IDENTIFIED IN SOUTHERN ITALY

alpha-thalassemia is a hereditary microcytic anemia caused by structural defects involving one or both of the duplicated 5'-3' alpha2 and alpha1 globin genes, on chromosome 16. The hematologic diagnosis is hindered by the absence of markers. Achieving a molecular diagnosis is relevant to the prevention of severe alpha- and beta-thalassemia. In an epidemiological study of molecular basis of alpha-thalassemia in Southern Italy were selected families showing microcytosis with normal level of HbA2 and iron. Molecular screening -through DGGE, gap-PCR, ARMS, MLPA and sequencing- brought us to identify the molecular basis in about 1300 chromosomes. Single point mutations account for the phenotype in 28% of carriers and among them, 4 mutations (alpha2IVS-I-5nt; alpha2AATAAA>AATAAG, -alpha3.7-AC, alpha2ATG>ACG)1 have the higher relative frequency, but there are an increasing number of new pointform mutations. We report below 6 new alleles: Hb Bernalda (alpha1 cod119 CCT>TCT), Hb Policoro (alpha2 cod124 TCC>CCC)2, Hb Sciacca (alpha1 cod109 CTG>-TG), HbA1 cod23 GAG>TAG Glu>Stop3, Hb Rogliano (alpha1 cod108 ACC>AAC)2, HbA1 cod22 GGC>GGT3. Hb Bernalda, Hb Policoro, Hb Sciacca, Hb Rogliano are unstable variants with alpha-thal phenotype, cod23 G>T generates a premature stop, cod22 C>T an alternative splicing site. Hb Bernalda is the 5th most frequent (5%), while Hb Sciacca, Hb Policoro and cod22 shown a frequencies comparable with Hb Constant Spring and Hb Icaria (2%), moreover they are found in several Italian regions. Cod22 and Hb Rogliano are identified respectively in 1 and 2 families. We set up an ARMS protocol for the genotyping of 5/6 of these new alleles. Misdiagnosis of alpha-thal leads to repeated and unnecessary haematological analysis to assess the presence of microcytosis. alpha-thal molecular screening usually consists in the analysis of a panel of the most common mutations widespread in the world. We identified 6 new alpha-thal mutants in several families of different Italian regions. As the 6 new alleles have a total frequency of 10%, some showing a geographic prevalence, we suggest to test for these mutants the samples negative at the analysis for the most frequent alpha-thal mutations. 1 Lacerra G, et al, Hematologica 2007,92(2):254-5; 2 Bisconte MG, et al, Plos one 2015,10(3):e0115738; 3 Cardiero G, et al, IJBCB 2017,91(PtB):212-222