title: New analytical tools and epidemiological data for the identification of HbA2 borderline subjects in the screening for beta-thalassemia.
abstract: The increase of HbA(2) is the most important feature in the identification of beta-thalassemia carriers. However, some carriers are difficult to identify, because the level of HbA(2) is not in the typical range. Few data are available concerning the prevalence of such unusual phenotypes, and knowing their expected prevalence could be helpful in detecting systematic drifts in the analytical systems for HbA(2) quantification. In this study we report a retrospective investigation in two centres with high prevalence of beta-thalassemia. The prevalence of borderline subjects was found to be 2.2 and 3.0%, respectively. The genotypes of a subgroup of these subjects were then analyzed and in about 25% of cases a mutation in the globin genes was identified. We conclude that the occurrence of HbA(2) borderline phenotypes is not a rare event. In order to obtain more accurate HbA(2) measurements the development of an international reference measurement system for HbA(2), based on quantitative peptide mapping, has been recently started. We believe that the innovative approach of our method could also be used as a model to develop accurate quantitative methods for other red cell proteins relevant to the biodynamic properties and the surface electrochemistry of erythrocytes.
authors.affiliation: CIRME, Dip. di Scienze e Tecnologie Biomediche, Università degli Studi di Milano, Via F.lli Cervi 93, Segrate, Italy. andrea.mosca@unimi.it
authors.forename: Andrea
authors.initials: A
authors.lastname: Mosca
authors.forename: Renata
authors.initials: R
authors.lastname: Paleari
authors.forename: Renzo
authors.initials: R
authors.lastname: Galanello
authors.forename: Carla
authors.initials: C
authors.lastname: Sollaino
authors.forename: Lucia
authors.initials: L
authors.lastname: Perseu
authors.forename: Franca Rosa
authors.initials: FR
authors.lastname: Demartis
authors.forename: Cristina
authors.initials: C
authors.lastname: Passarello
authors.forename: Antonino
authors.initials: A
authors.lastname: Giambona
authors.forename: Aurelio
authors.initials: A
authors.lastname: Maggio
mesh_terms: D000293:Adolescent; D000328:Adult; D001774:Blood Chemical Analysis / Q000379:methods*; D002648:Child; D004909:Erythrocyte Indices; D005260:Female; D005838:Genotype; D006443:Hemoglobin A2 / Q000032:analysis*; D006801:Humans; D008297:Male; D015995:Prevalence; D012015:Reference Standards; D017086:beta-Thalassemia / Q000097:blood / Q000175:diagnosis* / Q000453:epidemiology* / Q000235:genetics
chemical_list: D006443:Hemoglobin A2