The unstable repeat expansions of (CTG)n or (CCTG)n in the DMPK and ZNF9 genes cause the two known subtypes of myotonic dystrophy: (i) myotonic dystrophy type 1 (DM1) and (ii) myotonic dystrophy type 2 (DM2) respectively.
Both DM1 and DM2 are caused by unstable DNA repeats in untranslated regions of different genes: A (CTG)n repeat in the 3'-UTR of the DMPK gene and a (CCTG)n repeat in intron 1 of the CNBP (formerly ZNF9) gene, respectively.
The commonly recognized RNA gain-of-function mechanism of DM1 and DM2 suggests that the mutant CUG and CCUG RNAs play a critical role in myotonic dystrophies (DMs) without a significant role of DMPK and ZNF9.
The mutation responsible for DM1 is a CTG repeat in the 3' UTR of the dystrophia myotonica protein kinase gene (DMPK) on chromosome 19q13.3, while DM2 is caused by an unstable CCTG expansion in intron 1 of the zinc finger protein 9 gene (ZNF9) on chromosome 3q21.3.
Myotonic dystrophy type 1 is caused by a (CTG)n expansion in the 3' untranslated region of the DMPK gene in 19q13.3 and myotonic dystrophy type 2 by a (CCTG)n expansion in intron 1 of ZNF9 in 3q21.3.
Proximal myotonic myopathy (PROMM) was first described in 1994 as a multisystem disorder with similarity to myotonic dystrophy (DM), but without the abnormal (CTG)n expansion in the DM protein kinase (DMPK) gene.
Among them, the thermodynamically less stable TTTA and CCTG MDBs have been proposed to be the structural intermediates that cause TTTA and CCTG repeat expansions during DNA replication in <i>Staphylococcus aureus</i> pathogen and myotonic dystrophy type 2 patients, respectively.
Myotonic dystrophy type 2 (DM2) is an autosomal dominant muscular dystrophy caused by the expansion of an intronic tetranucleotide CCTG repeat in CNBP on chromosome 3.
These results show that [CCTG]n repeat expansion, differently from the DM1 mutation, does not influence the methylation status of the CNBP gene and suggest that other molecular mechanisms are involved in the pathogenesis of DM2.
Myotonic dystrophy type 2 (DM2) is a neuromuscular disease caused by an expansion of intronic CCTG repeats in the <i>CNBP</i> gene, which encodes a protein regulating translation and transcription.
The Genea066 human embryonic stem cell line was derived from a donated, fully commercially consented ART blastocyst, carrying expansion of CCTG repeats in exon 1 of the ZNF9 gene, indicative of Myotonic Dystrophy Type 2 (DM2).
Here, we report a patient with an 8 kb CCTG expansion in intron 1 of the CNBP gene, a mutation characteristic of myotonic dystrophy type 2 (DM2), whose first manifestation was "idiopathic" eosinophilic myositis.
Myotonic dystrophy type 2 (DM2) is an autosomal dominant, multisystem disorder caused by a CCTG tetranucleotide repeat expansion located in intron 1 of the zinc finger protein 9 gene (ZNF9 gene) on chromosome 3q 21.3.
Myotonic dystrophy type 2 (DM2) is an autosomal dominant multisystem disorder caused by CCTG repeat expansions within intron 1 of the ZNF9 gene on chromosome 3q.
Expansion of non-coding CTG and CCTG repeats in the 3' UTR of the myotonin protein kinase (DMPK) gene in Myotonic Dystrophy type 1 (DM1) and in the intron 1 of Zinc Finger Protein 9 (ZNF9) in Myotonic Dystrophy type 2 (DM2) represent typical non-coding mutations that cause the diseases mainly through transdominant effect on the RNA metabolism (splicing, translation and RNA stability).
Myotonic dystrophy type 2 (DM2, OMIM #602688) is a multisystemic hereditary degenerative disease caused by a tetranucleotide CCTG expansion in the ZNF9 gene.