Misdiagnosis of a beta-thalassemia heterozygote using a reverse dot-blot method may be caused by a polymorphic locus in the wild type sequence of the beta-globin gene.
Reverse dot-blot is an effective method for detecting beta-thalassemia (beta-thal) mutations. In this study, we report the cause of a misdiagnosis by reverse dot-blot. One patient with a beta-globin genotype that was initially diagnosed as a codon 17 (A>T) homozygote by reverse dot-blot at our Clinic, was later shown to be a codon 17 (A>T) heterozygote by direct sequencing of the amplified fragment and by sequence analysis of a recombinant T vector plasmid containing an amplified fragment of the beta-globin gene. A polymorphic locus around the mutation site within the haploid DNA that lacked the codon 17 mutation was identified. This result suggests that when reverse dot-blot is used for the genetic diagnosis of beta-globin, polymorphic loci around the mutation site should be taken into consideration, and more allele specific oligonucleotide probes should be designed according to the polymorphic loci.
Yi
Ping
P
Department of Obstetrics and Gynecology, Research Institute of Surgery, Daping Hospital, Third Military Medical University, Chongqing, People's Republic of China.
Guo
Jianxin
J
Chen
Zhuqin
Z
Liu
Qiang
Q
Yu
Lili
L
Xie
Haichang
H
Yan
Yaohua
Y
Zhong
Xiaolin
X
Li
Li
L
D001483:Base Sequence; D002675:Child, Preschool; D003062:Codon / Q000235:genetics; D004252:DNA Mutational Analysis / Q000379:methods; D017931:DNA Primers; D006579:Heterozygote; D006801:Humans; D015151:Immunoblotting / Q000379:methods*; D008969:Molecular Sequence Data; D016133:Polymerase Chain Reaction / Q000379:methods*; D011110:Polymorphism, Genetic; D012680:Sensitivity and Specificity; D017422:Sequence Analysis, DNA; D055544:beta-Globins / Q000235:genetics*; D017086:beta-Thalassemia / Q000175:diagnosis* / Q000235:genetics
D003062:Codon; D017931:DNA Primers; D055544:beta-Globins