Molecular characterization of a novel 55.1 kb (G)gamma((A)gammadeltabeta)(0)-thalassemia deletion in two Canadian families.

We report two Canadian families in which there are four carriers of a novel (G)gamma((A)gammadeltabeta)(0)-thalassemia deletion. The patients all have mild microcytosis and hypochromia, and elevated levels of Hb F ranging from 9.7 to 17.3%. The precise endpoints of the deletion have been identified and are unique relative to other forms of (G)gamma((A)gammadeltabeta)(0)-thal reported in the literature. The deletion encompasses approximately 55.1 kb, beginning approximately 1.6 kb downstream of the (G)gamma-globin gene and extending approximately 29.0 kb downstream of the beta-globin gene.