Molecular characterization of beta-thalassemia in Taiwan and the identification of two new mutations.
Polymerase chain reaction-based techniques were used to study the molecular defects of 480 unrelated beta-thalassemia heterozygotes in Taiwan. Analysis of artificially created restriction sites and gap-polymerase chain reaction were performed to detect four common mutations, i.e. IVS-II-654 (C-->T), codons 41/42 (-TCTT), codon 17 (A-->T), -28 (A-->G), and a deletional form of delta beta-thalassemia in the Chinese population. In cases with negative or ambiguous results with the aforementioned methods, direct DNA cycle sequencing using either S35-dATP or a fluorescent dye terminator, was carried out to determine the defects. A total of 14 different mutations have been found in this series. The IVS-II-654 mutation was the most common (39.6%), followed by the codons 41/42 mutation (37.9%). The four common genotypes accounted for 92.3% of defects. Two new mutations were detected: codon 31 (-C) and codons 40/41 (+T). Both defects resulted in a frameshift and a premature terminator, the former at codon 60, the latter at codon 43. Although we have studied our cases extensively, the molecular defects in seven alleles are still unknown.
Ko
T M
TM
Department of Medical Genetics, National Taiwan University Hospital, College of Medicine, Taipei.
Tseng
L H
LH
Hsu
P M
PM
Guu
I J
IJ
Lin
Y W
YW
Li
S F
SF
Lee
T Y
TY
Chuang
S M
SM
D000328:Adult; D001483:Base Sequence; D004252:DNA Mutational Analysis; D017931:DNA Primers / Q000737:chemistry / Q000378:metabolism; D005260:Female; D006580:Genetic Carrier Screening; D006801:Humans; D008297:Male; D008969:Molecular Sequence Data; D009154:Mutation; D016376:Oligonucleotides, Antisense / Q000737:chemistry; D016133:Polymerase Chain Reaction / Q000379:methods; D011247:Pregnancy; D011296:Prenatal Diagnosis; D017086:beta-Thalassemia / Q000175:diagnosis / Q000235:genetics*
D017931:DNA Primers; D016376:Oligonucleotides, Antisense