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Clinical and genetic analysis of the first known Asian family with myotonic dystrophy type 2.

Nakayama T, Nakamura H, Oya Y, Kimura T, Imahuku I, Ohno K, Nishino I, Abe K, Matsuura T - J. Hum. Genet. (2014)

Bottom Line: Repeat-primed PCR across the DM2 repeat revealed a characteristic ladder pattern of a CCTG expansion in all siblings.Southern blotting analysis identified the presence of 3400 repeats.Further DM2 studies in Asian populations are needed to define the clinical presentation of Asian DM2 and as yet unidentified phenotypic differences from Caucasian patients.

View Article: PubMed Central - PubMed

Affiliation: Department of Neurology, Yokohama Rosai Hospital, Yokohama, Japan.

ABSTRACT
Myotonic dystrophy type 2 (DM2) is more common than DM1 in Europe and is considered a rare cause of myotonic dystrophies in Asia. Its clinical course is also milder with more phenotypic variability than DM1. We herein describe the first known Asian family (three affected siblings) with DM2 based on clinical and genetic analyses. Notably, two of the affected siblings were previously diagnosed with limb-girdle muscular dystrophy. Myotonia (the inability of the muscle to relax) was absent or only faintly present in these individuals. The third sibling had grip myotonia and is the first known Asian DM2 patient. The three DM2 siblings share several systemic characteristics, including late-onset, proximal-dominant muscle weakness, diabetes, cataracts and asthma. Repeat-primed PCR across the DM2 repeat revealed a characteristic ladder pattern of a CCTG expansion in all siblings. Southern blotting analysis identified the presence of 3400 repeats. Further DM2 studies in Asian populations are needed to define the clinical presentation of Asian DM2 and as yet unidentified phenotypic differences from Caucasian patients.

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Related in: MedlinePlus

Repeat-primed PCR analysis specific for the DM2 expansion. Negative results from normal control (NC) are shown in the upper panel, whereas a characteristic continuous ladder from Case 2 (II2 in Figure 1), indicating the CCTG expansion, is detected in the lower panel. A full color version of this figure is available at the Journal of Human Genetics journal online.
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fig2: Repeat-primed PCR analysis specific for the DM2 expansion. Negative results from normal control (NC) are shown in the upper panel, whereas a characteristic continuous ladder from Case 2 (II2 in Figure 1), indicating the CCTG expansion, is detected in the lower panel. A full color version of this figure is available at the Journal of Human Genetics journal online.

Mentions: Three patients with DM2 CCTG expansion were identified in this pedigree. Case 3 has been reported previously.7 All cases showed one peak following PCR of the DM2 repeat and a characteristic ladder pattern by repeat-primed PCR,3, 7 confirming the presence of the CCTG expansion (Figure 2). DNA extracted from the Case 2 individual was degraded, so Southern blotting hybridization analysis was performed on the remaining two patients (Cases 1 and 3). This showed the presence of an 18.1 kb expanded DM2 allele, corresponding to 3400 CCTG repeats (Figure 3).


Clinical and genetic analysis of the first known Asian family with myotonic dystrophy type 2.

Nakayama T, Nakamura H, Oya Y, Kimura T, Imahuku I, Ohno K, Nishino I, Abe K, Matsuura T - J. Hum. Genet. (2014)

Repeat-primed PCR analysis specific for the DM2 expansion. Negative results from normal control (NC) are shown in the upper panel, whereas a characteristic continuous ladder from Case 2 (II2 in Figure 1), indicating the CCTG expansion, is detected in the lower panel. A full color version of this figure is available at the Journal of Human Genetics journal online.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC3973124&req=5

fig2: Repeat-primed PCR analysis specific for the DM2 expansion. Negative results from normal control (NC) are shown in the upper panel, whereas a characteristic continuous ladder from Case 2 (II2 in Figure 1), indicating the CCTG expansion, is detected in the lower panel. A full color version of this figure is available at the Journal of Human Genetics journal online.
Mentions: Three patients with DM2 CCTG expansion were identified in this pedigree. Case 3 has been reported previously.7 All cases showed one peak following PCR of the DM2 repeat and a characteristic ladder pattern by repeat-primed PCR,3, 7 confirming the presence of the CCTG expansion (Figure 2). DNA extracted from the Case 2 individual was degraded, so Southern blotting hybridization analysis was performed on the remaining two patients (Cases 1 and 3). This showed the presence of an 18.1 kb expanded DM2 allele, corresponding to 3400 CCTG repeats (Figure 3).

Bottom Line: Repeat-primed PCR across the DM2 repeat revealed a characteristic ladder pattern of a CCTG expansion in all siblings.Southern blotting analysis identified the presence of 3400 repeats.Further DM2 studies in Asian populations are needed to define the clinical presentation of Asian DM2 and as yet unidentified phenotypic differences from Caucasian patients.

View Article: PubMed Central - PubMed

Affiliation: Department of Neurology, Yokohama Rosai Hospital, Yokohama, Japan.

ABSTRACT
Myotonic dystrophy type 2 (DM2) is more common than DM1 in Europe and is considered a rare cause of myotonic dystrophies in Asia. Its clinical course is also milder with more phenotypic variability than DM1. We herein describe the first known Asian family (three affected siblings) with DM2 based on clinical and genetic analyses. Notably, two of the affected siblings were previously diagnosed with limb-girdle muscular dystrophy. Myotonia (the inability of the muscle to relax) was absent or only faintly present in these individuals. The third sibling had grip myotonia and is the first known Asian DM2 patient. The three DM2 siblings share several systemic characteristics, including late-onset, proximal-dominant muscle weakness, diabetes, cataracts and asthma. Repeat-primed PCR across the DM2 repeat revealed a characteristic ladder pattern of a CCTG expansion in all siblings. Southern blotting analysis identified the presence of 3400 repeats. Further DM2 studies in Asian populations are needed to define the clinical presentation of Asian DM2 and as yet unidentified phenotypic differences from Caucasian patients.

Show MeSH
Related in: MedlinePlus