Supraventricular and Ventricular Arrhythmias Are Related to the Type of Myotonic Dystrophy but Not to Disease Duration or Neurological Status

Life Expectancy and Causes of Death in Patients with Myotonic Dystrophy Type 2

Background

Myotonic Dystrophy type 2 (DM2) is a dominantly inherited multisystem disease caused by a CCTG repeat expansion in intron 1 of the CNBP gene. Although in the last two decades over 1500 patients with DM2 have been diagnosed worldwide, our clinical impression of a reduced life expectancy in DM2 has not been investigated previously.

Objective

The aim of this observational study was to determine the life expectancy and the causes of death in patients with genetically confirmed DM2.

Methods

We identified the data of all deceased patients with DM2 in the Dutch neuromuscular database between 2000 and 2023. Ages and causes of death and the patients' clinical features during lifetime were determined. Age of death in DM2 was compared to the general population by using life tables with prognostic cohort life expectancy (CLE) and period life expectancy (PLE) data of the Dutch electronic database of statistics (CBS StatLine).

Results

Twenty-six deceased patients were identified in the Dutch DM2 cohort (n = 125). Median age of death in DM2 (70.9 years) was significantly lower compared to sex- and age-matched CLE (78.1 years) and PLE (82.1 years) in the Netherlands. Main causes of death were cardiac diseases (31%) and pneumonia (27%). Seven patients (27%) had a malignancy at the time of death.

Conclusion

These results provide new insights into the phenotype of DM2. Life expectancy in patients with DM2 is reduced, possibly attributable to multiple causes including increased risk of cardiac disease, pneumonia, and malignancies. The occurrence of a significantly reduced life expectancy has implications for clinical practice and may form a basis for advanced care planning, including end-of-life care, to optimize quality of life for patients with DM2 and their family. Research in larger cohorts should be done to confirm these findings and to ascertain more about the natural course in DM2.

Outcome measures frequently used to assess muscle strength in patients with myotonic dystrophy type 1: a systematic review

Measurement of muscle strength is fundamental for the management of patients with myotonic dystrophy type 1 (DM1). Nevertheless, guidance on this topic is somewhat limited due to heterogeneous outcome measures used. This systematic literature review aimed to summarize the most frequent outcome measures to assess muscle strength in patients with DM1. We searched on Pubmed, Web of Science and Embase databases. Observational studies using measures of muscle strength assessment in adult patients with DM1 were included. From a total of 80 included studies, 24 measured cardiac, 45 skeletal and 23 respiratory muscle strength. The most common method and outcome measures used to assess cardiac muscle strength were echocardiography and ejection fraction, for skeletal muscle strength were quantitative muscle test, manual muscle test and maximum isometric torque and medical research council and for respiratory muscle strength were manometry and maximal inspiratory and expiratory pressure. We successfully gathered the more consensual methods and measures to evaluate muscle strength in future clinical studies, particularly to test muscle strength response to treatments in patients with DM1. Future consensus on a set of measures to evaluate muscle strength (core outcome set), is important for these patients.

WITHDRAWN: Evidence for a relatively high proportion of DM2 mutations in a large group of Polish patients

The Publisher regrets that this article is an accidental duplication of an article that has already been published, 10.1016/j.pjnns.2018.02.008. The duplicate article has therefore been withdrawn. The full Elsevier Policy on Article Withdrawal can be found at https://www.elsevier.com/about/our-business/policies/article-withdrawal.

Evidence for a relatively high proportion of DM2 mutations in a large group of Polish patients

INTRODUCTION

Myotonic dystrophies (DMs) type 1 (DM1) and type 2 (DM2) are autosomal dominant, multisystem disorders, considered the most common dystrophies in adults. DM1 and DM2 are caused by dynamic mutations in the DMPK and CNBP genes, respectively.

METHODS

Molecular analyses were performed by PCR and the modified RP-PCR in patients, in their at-risk relatives and prenatal cases.

RESULTS

The analysis of Polish controls revealed the range of 5-31 CTG repeats for DM1 and 110-228 bp alleles for DM2. Among 318 confirmed probands - 196 (62%) were DM1 and 122 (38%) - DM2. Within DM1families, 10 subjects carried a low expanded CTG tract (< 100 repeats), which resulted in a full mutation in subsequent generations. Two related individuals had unstable alleles-188 bp and 196 bp without common interruptions.

CONCLUSION

The relative frequencies of DM1/DM2 among Polish patients were 68% and 32%, respectively, with a relatively high proportion of DM2 mutations (1.6:1).

Low-symptomatic skeletal muscle disease in patients with a cardiac disease - Diagnostic approach in skeletal muscle laminopathies

Mild skeletal muscle symptoms might be accompanied with severe cardiac disease, sometimes indicating a serious inherited disorder. Very often it is a cardiologist who refers a patient with cardiomyopathy and/or cardiac arrhythmia and discrete muscle disease for neurological consultation, which helps to establish a proper diagnosis. Here we present three families in which a diagnosis of skeletal muscle laminopathy was made after careful examination of the members, who presented with cardiac arrhythmia and/or heart failure and a mild skeletal muscle disease, which together with positive family history allowed to direct the molecular diagnostics and then provide appropriate treatment and counseling.