A FAMILY WITH AN UNUSUAL MYOTONIC AND MYOPATHIC PHENOTYPE AND NO CTG EXPANSION (PROXIMAL MYOTONIC MYOPATHY SYNDROME) - A CHALLENGE FOR FUTURE MOLECULAR STUDIES
G. Meola et al., A FAMILY WITH AN UNUSUAL MYOTONIC AND MYOPATHIC PHENOTYPE AND NO CTG EXPANSION (PROXIMAL MYOTONIC MYOPATHY SYNDROME) - A CHALLENGE FOR FUTURE MOLECULAR STUDIES, Neuromuscular disorders, 6(3), 1996, pp. 143-150
Myotonic dystrophy (DM) is a well-defined autosomal dominant disorder
characterized by myotonia, muscle weakness, cardiac conduction defects
, cataracts, and endocrine abnormalities. Recently a newly recognized
disorder, similar to but distinct from DM, has been observed with mult
isystem findings including intermittent myotonia, proximal myopathy, a
nd occasional cardiac conduction disturbances. This disorder has been
called proximal myotonic myopathy (PROMM). No history of anticipation
is present and there is no linkage to the gene locus for DM or to the
loci for the muscle sodium or chloride channels. This report describes
a family with a normal size of the CTG trinucleotide repeat expansion
of the DM gene in which affected individuals have myotonia (intermitt
ent, exacerbated by cold), bilateral cataracts, mild hypogonadism and
mild temporal atrophy. Affected individuals also have proximal muscle
weakness, facial involvement, nonspecific abnormalities on muscle biop
sy, normal cardiac conduction, and no glucose intolerance. The absence
of trinucleotide repeat expansion in the DM gene is consistent with t
his family being affected by a disorder distinct from DM, possibly a f
orm of PROMM. Copyright (C) 1996 Elsevier Science Ltd.