Decrease in the size of the myotonic dystrophy CTG repeat during transmission from parent to child: Implications for genetic counselling and genetic anticipation

Abstract Myotonic dystrophy (DM) is an autosomal dominant genetic disease caused by an unstable CTG repeat sequence in the 3' untranslated region of the myotonin protein kinase gene. The CTG repeat is present 5-30 times in the normal population, whereas DM patients have CTG expansions of 50 to several thousand repeats. The age of onset of the disorder and the severity of the phenotype is roughly correlated with the size of the CTG expansion. We developed a molecular protocol for the diagnosis of DM based on an initial polymerase chain reaction screen to detect normal-sized alleles and small expansions, followed by an improved Southern protocol to detect larger expansions.

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Presymptomatic testing in myotonic dystrophy: genetic counselling approaches

Journal of Medical Genetics ◽

10.1136/jmg.38.12.846 ◽

2001 ◽

Vol 38 (12) ◽

pp. 846-850 ◽

Cited By ~ 15

Author(s):

S. Fokstuen

Keyword(s):

Myotonic Dystrophy ◽

Genetic Counselling ◽

Presymptomatic Testing

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Impact of prematurity and the CTG repeat length on outcomes in congenital myotonic dystrophy

BMC Research Notes ◽

10.1186/s13104-020-05186-z ◽

2020 ◽

Vol 13 (1) ◽

Author(s):

Yu Saito ◽

Kenta Matsumura ◽

Misao Kageyama ◽

Yuichi Kato ◽

Eiji Ohta ◽

...

Keyword(s):

Myotonic Dystrophy ◽

Repeat Length ◽

Congenital Myotonic Dystrophy ◽

Ctg Repeat

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Relation of cardiac abnormalities and CTG-repeat size in myotonic dystrophy

Clinical Genetics ◽

10.1034/j.1399-0004.2001.590509.x ◽

2002 ◽

Vol 59 (5) ◽

pp. 350-355 ◽

Cited By ~ 31

Author(s):

J Finsterer ◽

E Gharehbaghi-Schnell ◽

C Stöllberger ◽

K Fheodoroff ◽

A Seiser

Keyword(s):

Myotonic Dystrophy ◽

Cardiac Abnormalities ◽

Repeat Size ◽

Ctg Repeat

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Partial Syndrome of Myotonic Dystrophy: Clinical Presentation and Follow-up

Canadian Journal of Neurological Sciences / Journal Canadien des Sciences Neurologiques ◽

10.1017/s0317167100028614 ◽

1989 ◽

Vol 16 (1) ◽

pp. 99-103 ◽

Cited By ~ 6

Author(s):

Jean Mathieu ◽

Marcel Simard ◽

Marc De Braekeleer ◽

Camil Boily ◽

Aurèle Deschênes

Keyword(s):

Myotonic Dystrophy ◽

Genetic Counselling ◽

Clinical Presentation ◽

Dna Probes ◽

Average Period ◽

Reliable Identification ◽

Follow Up Study ◽

Gene Carriers ◽

Typical Form

ABSTRACT:The neurological and ophthalmological investigation of 602 members of 88 Saguenay kindreds affected by myotonic dystrophy (MyD) revealed 130 persons with a partial syndrome. These patients, whose average age was 34.1 years, showed different abnormalities such as particular ophthalmic and/or neuro-muscular signs, suggesting MyD in the absence of myotonia or typical lens abnormalities. After an average period of 2,4 years, 44 of these 130 patients were reassessed by the same neurologists and ophthalmologists. Thirty still had a partial syndrome, 8 showed a typical form of MyD and 6 no longer presented any identifiable anomaly. This preliminary follow-up study of the partial MyD syndrome did not allow us to identify any clinical anomaly from which the presence of the MyD gene could be predicted in a significant way. It furthermore suggested that the identification of equivocal or unspecific signs among these patients can sometimes lead to misdiagnosis. This must be taken into account when providing genetic counselling. It furthermore indicates that the use of DNA probes is essential for a reliable identification of asymptomatic MyD gene carriers.

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