Types of DM
Two well-defined, but overlapping types of myotonic dystrophy have been identified:
- DM1. The first type (also known as Steinert’s disease) is the most prevalent form of the condition and generally the most severe. This form affects at least 1 in 8,000 people worldwide, although the number may be far greater. There are three categories of DM1, categorized by when symptoms of the disease first appear:
- DM2. Myotonic dystrophy type 2, also known as proximal myotonic myopathy (PROMM), is a milder form of myotonic dystrophy in which transient muscle pain is the most common complaint. Only adult onset forms of DM2 have been recognized. To date, there have been few large scale or definitive studies to determine the prevalence of DM2. Other possible types, caused by different genetic mutations, are currently being investigated.
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