Hereditary persistence of fetal hemoglobin (HPFH) and δβ-thalassemia (δβ-thal) are heterogeneous disorders caused by deletions within the β-globin gene cluster. When combined with other β-thal mutations or structural hemoglobin (Hb) variants, these deletions give rise to clinical phenotypes ranging from an asymptomatic condition to β-thal major (β-TM). Overlap in hematological parameters and variability in expression of Hbs A2 and F make molecular testing necessary to distinguish clinically relevant deletions. Multiplex ligation-dependent probe amplification (MLPA) was used to screen for β-globin gene cluster deletions in 49 unresolved samples referred for a suspected β-thal anomaly. The 1.39 kb Black β(0), 3.5 kb Thai β(0), 118 kb Filipino β(0), 11.8 kb Black (δβ)(0), 13.4 kb Sicilian (δβ)(0), 35.8 kb Black ((A)γδβ)0, Hb Lepore-Boston-Washington (Hb LBW) and HPFH-2 deletions, and two novel deletions, a 61.7 kb Pakistani β(0) deletion and an ((A)γδβ)(0) deletion, were identified in 15 cases. Detection of both known and unknown deletional Hb disorders provides for appropriate clinical management and genetic counseling.
Three new γ-globin chain mutations were identified in four newborn samples referred to the Hemoglobinopathy Reference Laboratory at the Children's Hospital & Research Center Oakland, Oakland, CA, USA, for diagnostic testing. The variants were characterized by sequencing of amplified γ-globin genes. These three novel variants have been named Hb F-Hayward [(G)γ1(NA1)Gly→Asp, GGT>GAT], Hb F-Chori-I [(A)γ(T)16(A13)Gly→Asp, GGC>GAC] and Hb F-Chori-II [(A)γ(I)29(B11)Gly→Glu, GGA>GAA], respectively. No functional studies could be performed.
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