Known and new delta globin gene mutations and their diagnostic significance.
Mutations in the delta-globin gene (HBD, MIM# 142000) are not pathologically relevant. However, since high HbA2 levels are diagnostic for beta-thalassemia trait and a lowered level for an alpha- or delta-mutation, co-inheritance of delta- and beta-gene defects may lead to misinterpretation of diagnostic results. We examined 29 cases with low HbA2 level diagnosed in our laboratory, in the presence or absence of a second HbA2 fraction. We found a delta globin gene mutation in 20 cases. In total four different known mutations were found, three structural and one expressional. Moreover, two new defects were observed, one causing a structural abnormality and one a beta-thalassemia. The structural abnormality HBD c.431A->G (p.His144Arg)(dcd 143 CAC->CGC) was homologous to the beta-globin gene variant called Hb-Abruzzo and we have named this mutation HbA2 -Abruzzo. The new delta-thalassemia defect HBD c.-118C->T (d -68 C->T) has no homology on the beta-globin gene (HBB, MIM# 141900). All mutations caused a low HbA2 level and through this could lead to misdiagnosis when inherited together with a beta-thalassemia.
Bouva
Marelle J
MJ
Dept. of Human and Clinical Genetics, Leiden University Medical Center, Leiden, The Netherlands.
Harteveld
Cornelis L
CL
van Delft
Peter
P
Giordano
Piero C
PC
D005914:Globins / Q000235:genetics*; D006443:Hemoglobin A2 / Q000032:analysis; D006455:Hemoglobins, Abnormal / Q000235:genetics; D006801:Humans; D017354:Point Mutation; D017086:beta-Thalassemia / Q000175:diagnosis*
D006455:Hemoglobins, Abnormal; C067281:hemoglobin Abruzzo; D005914:Globins; D006443:Hemoglobin A2