Myotonic dystrophy is a relatively common type of muscular dystrophy, associated with a variety of systemic complications. Long term follow-up is difficult because of the slow progression. The objective of this study was to determine survival, age at death and causes of death in patients with the adult-onset type of myotonic dystrophy. A register of myotonic dystrophy patients was set up in Southern Limburg (the Netherlands), using data longitudinally collected over a 47-year period (1950-97). Survival for 180 patients (from the register) with adult-onset type myotonic dystrophy was established by the Kaplan-Meier method. The median survival was 60 years for males and 59 years for females. Survival of the patients was also estimated from the age of 15 years to the ages of 25, 45 and 65 years and compared with the expected survival of age- and sex-matched birth cohorts from the normal Dutch population. The observed survival to the ages of 25, 45 and 65 years was 99%, 88% and 18% compared with an expected survival of 99%, 95% and 78%, respectively. Thus, survival to the age of 65 in patients with adult-onset myotonic dystrophy is markedly reduced. A weak positive correlation between the CTG repeat length and younger age at death was found in the 13 patients studied (r = 0.50, P = 0.08). The cause of death could be determined in 70 of the 83 deceased patients. Pneumonia and cardiac arrhythmias were the most frequent primary causes of death, each occurring in approximately 30%, which was far more than expected for the general Dutch population. In addition, we assessed mobility in the years before death in a subgroup of 18 patients, as a reflection of the long-term physical handicap in myotonic dystrophy patients. Half of the patients studied were either partially or totally wheelchair-bound shortly before their death.

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BackgroundNeuropathic pain is common in peripheral neuropathy. Recent genetic studies have linked pathogenic voltage-gated sodium channel (VGSC) variants to human pain disorders. Our aims are to determine the frequency of SCN9A, SCN10A and SCN11A variants in patients with pure small fibre neuropathy (SFN), analyse their clinical features and provide a rationale for genetic screening.MethodsBetween September 2009 and January 2017, 1139 patients diagnosed with pure SFN at our reference centre were screened for SCN9A, SCN10A and SCN11A variants. Pathogenicity of variants was classified according to established guidelines of the Association for Clinical Genetic Science and frequencies were determined. Patients with SFN were grouped according to the VGSC variants detected, and clinical features were compared.ResultsAmong 1139 patients with SFN, 132 (11.6%) patients harboured 73 different (potentially) pathogenic VGSC variants, of which 50 were novel and 22 were found in ≥ 1 patient. The frequency of (potentially) pathogenic variants was 5.1% (n=58/1139) for SCN9A, 3.7% (n=42/1139) for SCN10A and 2.9% (n=33/1139) for SCN11A. Only erythromelalgia-like symptoms and warmth-induced pain were significantly more common in patients harbouring VGSC variants.Conclusion(Potentially) pathogenic VGSC variants are present in 11.6% of patients with pure SFN. Therefore, genetic screening of SCN9A, SCN10A and SCN11A should be considered in patients with pure SFN, independently of clinical features or underlying conditions.

From a series of 107 females with Rett syndrome (RTT), we describe the long-term history of ten females with a deletion in the C-terminus of the MECP2 gene. We observed that their disorder profile is clinically recognizable with time and different from other atypical and milder RTT phenotypes. In females with hot spot deletions in the C-terminus, dystonia is present from childhood and results in a serious spine deformation in spite of preventive measures. Their adaptive behavior is surprisingly better preserved and in contrast with the typical decline in motor functioning. The delineation of disorder profiles by long-term clinical observation can teach us about genotype/phenotype relationships and eventually about the effect of epigenetic phenomena on the final phenotype.

Our data show, for the first time, that carriers of heteroplasmic mtDNA mutations will have a fair chance of having healthy offspring, by applying PGD. Nevertheless, our conclusions are partly based on estimations and, as indicated, do not provide absolute certainty. Carriers of mtDNA should be informed about these constraints.