Homozygous beta-thalassaemia resulting in the beta-thalassaemia carrier state phenotype.
This paper describes the phenotypic manifestations of a very mild beta-thalassaemia mutation detected in several members of two families of Italian descent. The molecular defect, defined by denaturing gradient gel electrophoresis analysis and direct sequencing, consists of a C-->G substitution at position 844 of IVSII of the beta-globin gene within the consensus sequence of the IVSII acceptor splice site. Heterozygotes for this mutation show a haematological phenotype ranging in severity from silent beta-thalassaemia to that of a mild beta-thalassaemia carrier state, whereas homozygotes have the typical manifestations commonly resulting from heterozygosity for a beta-thalassaemia mutation. Compound heterozygotes for the IVSII nt844 (C-->G) mutation and a severe beta-thalassaemia mutation have the phenotype of thalassaemia intermedia. This paper indicates that the presence of borderline red blood cell indices or HbA2 values should make one suspect the presence of a very mild or silent beta-thalassaemia.
Rosatelli
M C
MC
Istituto di Clinica e Biologia dell'Età Evolutiva, Università degli Studi di Cagliari, Italy.
Pischedda
A
A
Meloni
A
A
Saba
L
L
Pomo
A
A
Travi
M
M
Fattore
S
S
Cao
A
A
D001483:Base Sequence; D004247:DNA / Q000032:analysis; D005260:Female; D006580:Genetic Carrier Screening; D006579:Heterozygote; D006720:Homozygote; D006801:Humans; D008297:Male; D008969:Molecular Sequence Data; D009154:Mutation; D010375:Pedigree; D017086:beta-Thalassemia / Q000235:genetics*
D004247:DNA