Phenotypic features and genetic findings in 2 chinese families with Miyoshi distal myopathy.
BACKGROUND
Miyoshi distal myopathy (MM) and limb girdle muscular dystrophy type 2B (LGMD2B) were found to map to the same mutant gene encoding for dysferlin on chromosome 2p13. Most reported cases were large inbred kindreds whose members demonstrated both MM and LGMD2B phenotypes.


OBJECTIVE
To investigate the clinical, neurophysiological, histopathological, and genetic features in 4 patients with MM from 2 unrelated Chinese families demonstrating linkage to the dysferlin locus.


RESULTS
All patients were characterized by early adult onset, preferential atrophy, and weakness of calf muscles, marked elevation of serum creatine kinase levels, and absence of dysferlin staining. Magnetic resonance imaging showed fatty and fibrotic tissue signals in the affected muscles. Genetic analysis revealed novel compound heterozygous mutations, 1310+1G to A and GGG to GTC transition at nucleotide 1650 (G426V ) in one family and another novel compound heterozygous mutation, a deletion of C at nucleotide 477 and a CCG to CTG transition at nucleotide 6576 (P2068L), in the other family.


CONCLUSIONS
Miyoshi distal myopathy in these 2 Chinese families demonstrated a homogenous phenotype and compound heterozygous mutations. Among the 4 mutations, 3 were novel mutations that, to our knowledge, have not been reported previously.
Ro
Long-Sun
LS
Department of Neurology, Chang Gung Memorial Hospital, Taipei 10591, Taiwan. cgrols@adm.cgmh.org.tw
Lee-Chen
Guey-Jen
GJ
Lin
Tzu-Ching
TC
Wu
Yih-Ru
YR
Chen
Chiung-Mei
CM
Lin
Cheng-Yueh
CY
Chen
Sien-Tsong
ST
D000293:Adolescent; D000328:Adult; D044466:Asian People; D004252:DNA Mutational Analysis / Q000379:methods; D049310:Distal Myopathies / Q000235:genetics* / Q000473:pathology; D000073939:Dysferlin; D005091:Exons; D005192:Family Health; D005260:Female; D008040:Genetic Linkage; D005838:Genotype; D005998:Glycine / Q000235:genetics; D006801:Humans; D007150:Immunohistochemistry / Q000379:methods; D007930:Leucine / Q000235:genetics; D008279:Magnetic Resonance Imaging / Q000379:methods; D008297:Male; D008565:Membrane Proteins / Q000235:genetics*; D009124:Muscle Proteins / Q000235:genetics* / Q000378:metabolism; D018482:Muscle, Skeletal / Q000473:pathology; D009135:Muscular Diseases / Q000235:genetics / Q000473:pathology; D009154:Mutation / Q000235:genetics; D010375:Pedigree; D010641:Phenotype; D018807:Polymorphism, Single-Stranded Conformational; D011392:Proline / Q000235:genetics; D014633:Valine / Q000235:genetics
C114839:DYSF protein, human; D000073939:Dysferlin; D008565:Membrane Proteins; D009124:Muscle Proteins; D011392:Proline; D007930:Leucine; D014633:Valine; D005998:Glycine