Document Detail

CTG trinucleotide repeat length and clinical expression in a family with myotonic dystrophy.
MedLine Citation:
PMID:  8733904     Owner:  NLM     Status:  MEDLINE    
Unstable expansion of the CTG repeats in the 3' untranslated region encoding a member of the protein kinase family in the q13.3 band on chromosome 19 is a mutation specific for myotonic dystrophy. To examine the correlation between clinical expression and CTG trinucleotide repeat length, we carried out Southern blot analysis in a family with myotonic dystrophy. In this pedigree, the expanded CTG repeats were transmitted maternally. The mother had three female children. The mother had about 200 CTG repeats, and the number of repeats for each child was about 800, 1500 and 1600 in birth order. The mother and the patient with 800 repeats were unaware of muscle weakness or myotonia. Symptoms were present from age 3 years in the patient with 1500 repeats and from birth in the one with 1600 repeats. Although the mother menstruated regularly, the patients with 800 and 1500 repeats both menstruated irregularly, and the one with 1600 repeats has never menstruated. The age of onset and severity of the disease were correlated with the size of the expanded repeats. Endocrinological studies revealed that the basal levels of the gonadotropins, PRL and E2 were within normal range, and a pituitary response to LHRH was observed. These data suggest that the amenorrhea and menstrual irregularities were caused by a suprahypophyseal dysfunction. When expanded CTG repeats are transmitted maternally, abnormal products resulting from the metabolic disturbance in the affected mother may harm the fetus in utero. A heterozygous fetus, who has more CTG repeats, may be unable to metabolize the pathologic products sufficiently and therefore may become more severely affected. This may explain the exclusive maternal transmission of congenital myotonic dystrophy.
S Takahashi; A Miyamoto; J Oki; A Okuno
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Publication Detail:
Type:  Case Reports; Journal Article    
Journal Detail:
Title:  Brain & development     Volume:  18     ISSN:  0387-7604     ISO Abbreviation:  Brain Dev.     Publication Date:    1996 Mar-Apr
Date Detail:
Created Date:  1996-11-05     Completed Date:  1996-11-05     Revised Date:  2004-11-17    
Medline Journal Info:
Nlm Unique ID:  7909235     Medline TA:  Brain Dev     Country:  NETHERLANDS    
Other Details:
Languages:  eng     Pagination:  127-30     Citation Subset:  IM    
Department of Pediatrics, Asahikawa Medical College, Japan.
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MeSH Terms
Blotting, Southern
DNA Mutational Analysis
Dysmenorrhea / blood,  genetics
Gonadal Steroid Hormones / blood
Muscular Dystrophies / blood,  genetics*,  physiopathology
Polymorphism, Restriction Fragment Length
Trinucleotide Repeats*
Reg. No./Substance:
0/Gonadal Steroid Hormones

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