Origin of a regressed myotonic dystrophy allele.

Giordano, Mara; Angelis, M. S. De; Mutani, Roberto; Richiardi, P.

doi:10.1136/jmg.31.2.130

Cited by 7 publications

(2 citation statements)

References 11 publications

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“…The largest contraction seen in our families studied ( -2.5 kb) was associated with very little changes in the clinical phenotype even taking into account the age of the affected offspring. These findings are in accordance with previous observations in other groups of patients (20,(38)(39)(40)(41)(42)(43)(44)(45)(46). We observed, however, no reverse mutation to a normal-sized allele in our DM-patients as has been reported previously (38,41,42,47).…”

Section: Discussionsupporting

confidence: 94%

Genotype ‐phenotype correlation in myotonic dystrophy

Gharehbaghi-Schneli¹,

Finsterei²,

Korschineck³

et al. 1998

Clinical Genetics

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Myotonic dystrophy (DM) is caused by a mutation in the length of a trinucleotide (CTG) repeat in the 3' untranslated region of the my‐otonin protein kinase gene located on chromosome 19q13.3. The normal gene has between 5 and 36 CTG trinucleotide repeats, whereas minimally affected individuals have 50 copies and severely affected DM‐patients have several thousands of such repeats. Since no information on a genotype‐phenotype correlation in Austrian DM‐patients is available, we examined a small group of these patients for the unstable trinucleotide repeat. Molecular analysis was used to clarify equivocal clinical diagnoses and confirm clinical findings. We studied eight DM‐families, a total of 57 individuals, of whom 18 were diagnosed with a trinucleotide repeat expansion. Twenty‐six unrelated individuals served as a control. Clinical assessment was based on the muscular disability rating scale (MDRS) and a sum of symptoms score (SSS). There was a significant correlation between the clinical scores (MDRS: Spearman r = 0.51: p = 0.029; SSS: Spearman r = 0.538; p = 0.0259) used and the size of the amplification of the trinucleotide repeat. The largest expansion found in our group of patients was 6 kb. Furthermore, we observed both expansion and contraction of the enlarged fragment during transmission from one generation to the next.

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Section: Discussionsupporting

confidence: 94%

Genotype ‐phenotype correlation in myotonic dystrophy

Gharehbaghi-Schneli¹,

Finsterei²,

Korschineck³

et al. 1998

Clinical Genetics

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“…Subject 11-1 requested genetic counselling for his 7-year-old son who was negative at neurological examination and had normal serum creatine kinase. Southern blot analysis of all family B members (Giordano et al 1994) detected an expanded fragment of about 100 triplet repeats at the DM locus in subjects 11-1 and 11-3. In subjects 1-1 and 111-1 PCR-amplified DNA showed the presence of a 60-repeat fragment, allowing a preclinical diagnosis of DM in both these individuals.…”

Section: I1mentioning

confidence: 99%

Problems arising in correlating clinical and molecular data in myotonic dystrophy

et al. 1995

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The number of copies of CTG trinucleotide repeats in the myotonic dystrophy gene correlates to a certain degree with the clinical symptoms in the patient. Routine molecular analysis of myotonic dystrophy is performed on peripheral blood cells, detecting the size of the expansion in leukocytes. However, in some cases somatic mosaicism is responsible for the presence of differently sized myotonic dystrophy alleles in different tissues of the same affected individual, complicating diagnosis and prognosis. Here we report two cases in which the correlation between molecular and clinical analysis performed with standard procedures posed some interpretative problems. The first individual was affected by an atypical clinical picture of myotonic dystrophy, the severity of which was not correlated with the low number of triplet repeats detected in his leukocyte DNA. The second case illustrates a prognostic problem in the presence of a low degree expansion in leukocytes. These examples outline the limits of standard molecular and clinical analysis in myotonic dystrophy.

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Myotonic Dystrophy

Waring¹,

Korneluk²

1998

Trinucleotide Diseases and Instability

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Origin of a regressed myotonic dystrophy allele.

Cited by 7 publications

References 11 publications

Genotype ‐phenotype correlation in myotonic dystrophy

Genotype ‐phenotype correlation in myotonic dystrophy

Problems arising in correlating clinical and molecular data in myotonic dystrophy

Myotonic Dystrophy

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