A > 200 kb deletion removing the entire β-like globin gene cluster in a family of Irish Descent

Abstract

We describe a new deletional form of γδβ-thalassemia segregating in two generations of a family of Irish descent. Affected family members present with a β-thalassemia minor phenotype, normal Hb A₂ and Hb F levels. Genomic blotting analyses on DNA from affected family members show heterozygosity for a large deletion beginning at least 15 kb upstream of the 5′ endpoint of the γδβ-thalassemia-1 deletion, extending through the entire β-like globin gene cluster, and continuing for at least 10 kb beyond the 3′ endpoint of the deletion associated with the Spanish form of δβd`-thalassemia. This deletion is among the largest described so far, and removes at least 205 kb encompassing the entire β-like globin gene cluster on chromosome 11.