Multiple families, predominantly of German descent and with clinically variable presentation that included proximal myotonic myopathy (PROMM) and type 2 DM (DM2) but without the DM1 mutation, showed linkage to the 3q21 region and were recently shown to segregate a (CCTG)(n) expansion mutation in intron 1 of ZNF9.
Proximal myotonic myopathy/myotonic dystrophy type 2 (PROMM/DM 2) is caused by an expansion of the (TG)n(TCTG)n(CCTG)n repeat tract in intron 1 of the ZNF9 gene located on chromosome 3q21.
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.
The majority of proximal myotonic myopathy syndromes reported so far have been related to the myotonic dystrophy (DM) type 2 (DM2) mutation, an expanded (CCTG)n repeat in the ZNF9 gene.
Myotonic dystrophy type 2 (DM2) is caused by a dominantly transmitted CCTG repeat expansion in intron 1 of the zinc finger protein 9 (ZNF9) gene on chromosome 3q.
Characterization of a single nucleotide polymorphism in the ZNF9 gene and analysis of association with myotonic dystrophy type II (DM2) in the Italian population.
Myotonic dystrophy type 2 (DM2) is a dominantly inherited disorder with multisystemic clinical features, caused by a CCTG repeat expansion in intron 1 of the zinc finger protein 9 (ZNF9) gene.
To address the issue of ZNF9 role in DM2, we have analyzed the effects of (CCTG)n expansion on ZNF9 expression in lymphoblastoid cell lines (n=4) from DM2 patients.
These disorders are distinguished from myotonic dystrophy type 1 (DM-1), the more recently described proximal myotonic myopathy/myotonic dystrophy type 2 (PROMM/DM-2), and proximal myotonic dystrophy (a variant of DM-2) by characteristic clinical features, lack of abnormal nucleotide repeat expansions in the DM-1 and DM-2 genes, lack of cataracts and endocrine disturbances, and absence of significant histopathology in the muscle biopsy.
Proximal myotonic myopathy (DM2, PROMM) has not been reported in patients younger than 18 years, and apparent lack of congenital and childhood forms is thought to be one of the distinctive clinical characteristics of this trait.
Myotonic dystrophy type 2 (DM2) is an autosomal dominant multisystemic disorder caused by a CCTG repeat expansion in intron 1 of the zinc finger protein 9 (ZNF9) gene.
This finding suggests that the Z-DNA-forming sequence in the DM2 gene locus may have a protective effect of reducing the potential for slipped-strand DNA formation in (CCTG)(n) x (CAGG)(n) repeats.
Myotonic dystrophy type 2 (DM2) is an autosomal dominant multisystemic disorder caused by a CCTG expansion in intron 1 of the zinc finger protein 9 gene on chromosome 3.