Despite the more recent genetic classification of the novel myotonic dystrophies into at least two distinct myotome dystrophy (DM) loci (DM1, DM2/PROMM/PDM), the clinical characteristics of these dominant myotonic syndromes often blur. The multisystemic nature of these disorders leads to a spectrum of symptoms and signs th.it emphasize the similarities and differences between these diseases. This review focuses en the clinical, laboratory, and genetic findings in 3q-linked and unlinked Italian families with proximal myotonic myopathy (PROMM). From a neuromuscular and cardiac point of view, we present follow-up data fom 25 patients studied serially over a 6-year period. We also present data on central nervous system involvement following neuropsychologic arid neuroimaging studies in this same period of time.