Myotonic Dystrophy Associated With Hereditary Motor and Sensory Neuropathy

Abstract

Thirteen members of a large family presented with a hereditary motor and sensory neuropathy (HMSN); 8 of them also showed more or less prominent signs of myotonic dystrophy (MyD). There were no cases with MyD alone. The disorder showed segregation with genetic markers for the MyD gene on chromosome 19. This was also true for the 5 subjects in which clinically only HMSN had been detected, 3 of whom were young children. This is the first time that a form of HMSN has been found to be coded for by a gene localized on chromosome 19. The syndrome could be caused by an allelic form of the 'common' MyD gene or by two closely linked genes on chromosome 19.

Abnormalities of nerve conduction studies in myotonic dystrophy type 1: Primary involvement of nerves or incidental coexistence?

“…At the same time, controversy continues about whether PN in DM1 is primary or secondary to other causes such as diabetes or drugs. 3,4,[10][11][12] Patient 18 in this study was evaluated carefully to check for other possible causes of PN, such as metabolic, nutritional, or genetic factors, but we found no other causes of PN. An oral glucose tolerance test involving a 75 g glucose load showed normal fasting and postprandial serum glucose concentrations.…”

“…Until recently, it was thought that PN may coexist with DM1. 3,4,12 Some authors have insisted that PN is not uncommon and exists in 20%-30% of patients with DM1. [18][19][20][21] This thesis is supported by electrophysiological, 18,21,22 pathological, 20 and clinical findings.…”

“…8,9 Given the assumption that PN exists in patients with DM1, there is disagreement about whether the PN is primary or secondary to other causes such as diabetes or the effects of drugs. 3,4,[10][11][12] The aims of this study were to evaluate the frequency and characteristics of abnormal nerve conduction in patients with DM1 and to assess the association between nerve conduction and the clinical features of DM1. We also analyzed a calculated index of early polyneuropathy to study the existence of early-stage PN in patients with DM1.…”

Combination of myotonic dystrophy and hereditary motor and sensory neuropathy

“…In the literature there are controversial results for the involvement of the peripheral nervous system in DM. Axonopathy was reported, involving both the motor and the sensory nerves, rather than demyelination in electrophysiological investigation of DM patients [4][5][6][7][8][9]. However, morphological and morphometric analyses of DM1 transgenic mice, carrying 300 CTG repeats, did not reveal axonal degeneration, sensory and motor neuropathy and a significant demyelination [10].…”

Encephalopathic attacks in a family co-segregating myotonic dystrophy type 1, an intermediate Charcot-Marie-Tooth neuropathy and early hearing loss

“…In 1986, we described 13 family members with clinical and electromyographic features of hereditary motor and sensory neuropathy, eight of them also exhibiting clinical or electromyographic signs of myotonic dystrophy. Genetic linkage studies with markers for chromosomes 1 and 19 strongly suggested that the disorder was caused by a single mutation at the DM1 locus, or by two closely linked mutations, on chromosome 19 3. In a follow-up study, 10 patients (nine from the original study and one additional patient) and 25 clinically unaffected relatives were investigated using recombinant DNA technology.…”