Delineation of CTG repeats and clinical features in a Taiwanese myotonic dystrophy family.
Myotonic dystrophy (DM) is an inherited, autosomal dominant muscular disease which is primarily caused by a CTG trinucleotide expansion mutation on chromosome 19q13.3. The size of this trinucleotide repeat is related both to the age of onset and to the severity of the clinical manifestation. This disease is very rare in Taiwan, and clinical and genetic study on DM has not yet been documented in this area. Here, we present both clinical features and degrees of CTG expansion for a Taiwanese DM family. All of the DM patients examined in this family showed obvious clinical manifestations by age 30, which included facial and limb muscle weakness with atrophy, myotonia, and ptosis. In addition, individual DM members also exhibited variable phenotypes, which may reflect the complexity of the pathogenic mechanism. Because the collection of blood specimens was considered to be an invasive procedure, a genetic study on this DM family was performed using buccal cells. Our results confirmed that four members showing classic symptoms of DM had CTG repeat expansion in the DMI locus, and that one member with ptosis and minor muscle weakness in the right foot was a normal homozygote for CTG repeat. These data demonstrate that buccal cells can provide clear and reliable results, and thus, are suitable for a family study of DM.
Department of Neurology, China Medical College Hospital, Taichung, Taiwan, ROC.
S B
SB
Jou
H M
HM
Lin
H
H
Pan
Y L
YL
Chiu
S Y
SY
Li
C C
CC
Lee
K M
KM
Hsiao
D000483:Alleles; D015139:Blotting, Southern; D005260:Female; D005838:Genotype; D006801:Humans; D008297:Male; D009061:Mouth Mucosa / Q000648:ultrastructure; D009223:Myotonic Dystrophy / Q000453:epidemiology / Q000235:genetics*; D010375:Pedigree; D010641:Phenotype; D016133:Polymerase Chain Reaction; D013624:Taiwan / Q000453:epidemiology; D019680:Trinucleotide Repeat Expansion