A report of Hb Fontainebleau [α21 (B2) Ala > Pro] as a result of founder effect phenomenon

Abstract

ObjectiveTo date, more than 400 alpha chain variants or point mutations in the α-globin genes that lead to single amino acid substitutions have been described. Here, we state a rare alpha-globin gene variant Hb Fontainebleau [a21 (B2) Ala>Pro] identified in heterozygote state in two families from the north of Iran during premarital thalassemia screening program. MaterialTwo first cousin couples with reduced hematological indices compatible with α-thalassemia were referred to Lab for premarital screening of thalassemia. At first CBC and capillary electrophoresis tests were applied. For molecular investigation genomic DNA was isolated from peripheral blood samples. Then, multiplex-Gap PCR and Sanger sequencing techniques were applied to discover common α- globin deletions and probable point mutations, respectively. ResultsIn the capillary electrophoresis results, one unknown peak was observed to the left of Hb A. Sanger sequencing results revealed that all cases are heterozygote for Hb Fontainebleau (HBA2: c.64G4C, p.Ala21Pro). Family history analysis has shown that all presented cases have belonged to the families which are originally from India. ConclusionThe presence of Hb Fontainebleau in Mazandaran province and in subjects with Indian origin may indicate the founder effect phenomenon. DNA analysis of subjects with reduced hematological indices is recommended for finding common and rare mutations to predict childbirth with thalassemia in premarital screening programs.