Outcome and effect of pregnancy in myotonic dystrophy type 2

Maternal health and obstetric complications of genetic neuromuscular disorders in pregnancy: A systematic review

BACKGROUND

Genetic neuromuscular disorders affect muscle function and control by the nervous system, presenting significant clinical challenges, particularly during pregnancy.

OBJECTIVES

To systematically review the literature on the obstetric outcomes and complications in women with genetic neuromuscular disorders.

SEARCH STRATEGY

We searched PubMed/Medline, Scopus, and CINAHL Ultimate from inception till June 2024 using terms like "pregnancy", "genetic neuromuscular disorder", "myotonic dystrophy", "maternal health" etc. SELECTION CRITERIA: Pregnant women with genetic neuromuscular disorders.

DATA COLLECTION AND ANALYSIS

Screening, selection, and data extraction were performed independently by two reviewers.

MAIN RESULTS

A total of 28 studies from 1978 to 2023 examined pregnancy outcomes in women with genetic neuromuscular disorders. The disorders included myotonic dystrophy, spinal muscular atrophy (SMA), Charcot-Marie-Tooth disease (CMT), and others. Common complications were polyhydramnios, preterm labor, miscarriages, and cesarean sections. Myotonic dystrophy type 1 (DM1) showed higher neonatal risks than type 2 (DM2). Women with SMA faced exacerbated muscle weakness, while CMT and limb-girdle muscular dystrophy were associated with preterm labor and cesarean deliveries. Pompe disease exacerbated symptoms, and GNE myopathy showed similar pregnancy outcomes to the general population. Non-dystrophic myotonias had higher fetal distress and postpartum complications.

CONCLUSIONS

Women with genetic neuromuscular disorders face increased pregnancy complications, including preterm labor, cesarean sections, and disease symptom exacerbation. Multidisciplinary care between neurologists and obstetricians is essential in managing these high-risk pregnancies effectively, ensuring better maternal and neonatal outcomes. Further research is needed to develop standardized care protocols and improve clinical management.

International collaboration to improve knowledge on myotonic dystrophy type 2

BACKGROUND

The TREAT-NMD Global Registry Network is a global collaboration of neuromuscular disease registries, including myotonic dystrophy type 2 (DM2), which aims to facilitate collaborative research and clinical trials.

OBJECTIVES

This study aimed to assess DM2 patients included in the network, and to analyse their socio-demographic and clinical features.

METHODS

Data were collected through email surveys sent to 16 TREAT-NMD myotonic dystrophy core member registries. 10 registries enrolled DM2 patients.

RESULTS

The total number of DM2 cases was 1,720, with the Czech, German, and USA registries enrolling the most patients (445, 430, and 339 cases, respectively). The highest rates were seen in Czechia and Serbia (4.2 and 2.0 registered per 100,000 population, respectively). High DM2:DM1 ratios were seen in Central Europe. The median age at registry entry was 51 years. Symptom onset occurred before age 20 in 14% of cases. One fifth of patients used an assistive device to walk, and 4% were non-ambulatory. Insertion of a pacemaker or implantable cardioverter-defibrillator was reported in 4% of subjects, while 7% used non-invasive ventilation.

CONCLUSIONS

This represents the largest DM2 cohort assembled to date, providing demographic and clinical data for future research and trial recruitment, illustrating TREAT-NMD's international reach and the importance of capturing DM2 data.

The current clinical perception of myotonic dystrophy type 2

PURPOSE OF REVIEW

Myotonic dystrophy type 2 (DM2) is a genetic disorder belonging to the spectrum of myotonic dystrophies. DM2 is characterized by progressive muscle weakness, wasting and muscle pain (myalgia), but can also affect many other organ systems. In this review, we provide an updated overview on the research literature on DM2 with a focus on the management of multisystemic involvement and atypical clinical phenotypes.

RECENT FINDINGS

Recent studies have focused on different aspects of multisystemic involvement. Early and severe cardiac involvement can occur in DM2 and needs to be managed appropriately. Diabetes has been shown to be more common in DM2 than in DM1, while a combination of symptoms (cataracts, myotonia, tremor) can be used to raise clinical suspicion and initiate genetic testing for DM2. Autoimmune disease has been shown to occur in up to one-third of DM2 patients, possibly due to altered immune pathways. New evidence also suggests a childhood-onset phenotype presenting with foot deformities.

SUMMARY

The multisystemic aspects of the disease require a multidisciplinary approach for some patients, most likely even including state-of-the-art cardiac and brain imaging to detect and treat complications earlier. Of note, our concept of DM2 as an adult-onset disease is somewhat challenged by evidence suggesting a few pediatric DM2 patients and possibly anticipation, at least in some DM2 families. More studies, including larger cohorts, are needed to better understand this possible early-onset DM2 phenotype variant.

Parent-of-Origin Effect on the Age at Symptom Onset in Myotonic Dystrophy Type 2

Background and Objectives

The existence of clinical anticipation, congenital form, and parent-of-origin effect in myotonic dystrophy type 2 (DM2) remains uncertain. Here, we aimed at investigating whether there is a parent-of-origin effect on the age at the first DM2-related clinical manifestation.

Methods

We identified patients with genetically confirmed DM2 with known parental inheritance from (1) the electronic medical records of our institutions and (2) a systematic review of the literature following the PRISMA 2020 guidelines and recorded their age at and type of first disease-related symptom. We also interrogated the Myotonic Dystrophy Foundation Family Registry (MDFFR) for patients with DM2 who completed a survey including questions about parental inheritance and age at the first medical problem which they related to their DM2 diagnosis.

Results

A total of 26 patients with DM2 from 18 families were identified at our institutions as having maternal (n = 14) or paternal (n = 12) inheritance of the disease, whereas our systematic review of the literature rendered a total of 61 patients with DM2 from 41 families reported by 24 eligible articles as having maternal (n = 40) or paternal (n = 21) inheritance of the disease. Both cohorts were combined for downstream analyses. Up to 61% and 58% of patients had muscle-related symptoms as the first disease manifestation in maternally and paternally inherited DM2 subgroups, respectively. Four patients developed hypotonia at birth and/or delayed motor milestones early in life, and 7 had nonmuscular presentations (2 had cardiac events within the second decade of life and 5 had cataracts), all of them with maternal inheritance. A maternal inheritance was associated with an earlier (within the first 3 decades of life) age at symptom onset relative to a paternal inheritance in this combined cohort, and this association was independent of the patient's sex (OR [95% CI] = 4.245 [1.429-13.820], p = 0.0117). However, this association was not observed in the MDFFR DM2 cohort (n = 127), possibly because age at onset was self-reported, and the information about the type of first symptom or medical problem that patients related to DM2 was lacking.

Discussion

A maternal inheritance may increase the risk of an early DM2 onset and of cataracts and cardiovascular events as first DM2 manifestations.

Pregnancy and myopathies: Reciprocal impacts between pregnancy, delivery, and myopathies and their treatments. A clinical review

During pregnancy, women undergo physical and physiological changes, which can impact the neuromuscular disease course, but also delivery and fetus health. Generally, there is little impact on the disease course, but sometimes an impairment is noticed, which could be attributed to pregnancy and not to disease progression. Cardiac and respiratory functions have to be assessed at the beginning of pregnancy and a close follow-up is mandatory in case of disorder. Labour and delivery are often impacted. Labour is prolonged because of muscle weakness that is an increased risk of instrumental delivery or Cesarean sections. Patients with myotonic dystrophy are at risk of postpartum hemorrhage. Fetal loss can be associated with fetal disease in myotonic dystrophy, and is at high risk for patients with active inflammatory myopathy only.

Myotonic dystrophy type 2: the 2020 update

The myotonic dystrophies are the commonest cause of adult-onset muscular dystrophy. Phenotypes of DM1 and DM2 are similar, but there are some important differences, including the presence or absence of congenital form, muscles primarily affected (distal vs proximal), involved muscle fiber types (type 1 vs type 2 fibers), and some associated multisystemic phenotypes. There is currently no cure for the myotonic dystrophies but effective management significantly reduces the morbidity and mortality of patients. For the enormous understanding of the molecular pathogenesis of myotonic dystrophy type 1 and myotonic dystrophy type 2, these diseases are now called "spliceopathies" and are mediated by a primary disorder of RNA rather than proteins. Despite clinical and genetic similarities, myotonic dystrophy type 1 and type 2 are distinct disorders requiring different diagnostic and management strategies. Gene therapy for myotonic dystrophy type 1 and myotonic dystrophy type 2 appears to be very close and the near future is an exciting time for clinicians and patients.

Maternal genetic disorders and fetal development

With improvements in early diagnosis and management of genetic diseases, more women with genetic disorders are reaching reproductive age and becoming pregnant. While pregnancy can have a significant impact on a woman's health when there is an underlying genetic disorder, there can also be fetal effects, including embryopathy, fetal growth restriction, and brain injury. Some maternal genetic disorders are associated with adverse perinatal outcomes, including a high risk of perinatal loss and preterm birth. In this article, we review several maternal genetic disorders associated with fetal risk that are important for clinicians and patients to understand and manage appropriately. These include phenylalanine hydroxylase (PAH) deficiency and other inborn errors of metabolism, tuberous sclerosis complex, myotonic dystrophy, cystic fibrosis, Turner syndrome, sickle cell disease, and connective tissue disorders.

Neuromuscular disorders in pregnancy

Many neuromuscular disorders preexist or occur during pregnancy. In some cases, pregnancy unmasks a latent hereditary disorder. Most available information is based on case reports or series or retrospective clinical experience or patient surveys. Of special interest are pregnancy-induced changes in disease course or severity and likelihood for baseline recovery of function postpartum. Labor and delivery present special challenges in many conditions that affect skeletal but not smooth (uterine) muscle; so labor complications must be anticipated. Anesthesia for cesarean section surgery requires special precautions in many disorders. The types of conditions reviewed are broad and include examples of autoimmune, hereditary, and compressive/mechanical processes. Disorders include carpal tunnel syndrome and other focal neuropathies, Bell palsy, myasthenia gravis, and other neuromuscular junction disorders, acute and chronic inflammatory neuropathy, hereditary and acquired muscle diseases, spinal muscular atrophy, amyotrophic lateral sclerosis, channelopathies, autonomic neuropathy, and dysautonomia. Many commonly used therapies have fetal animal but no proven human toxicity concerns, complicating treatment and risk decisions. Weaning off effective therapeutic agents or preemptive aggressive treatment or surgery prior to planned pregnancy is an option in some conditions.

Obstetrical, maternal and neonatal outcomes in pregnancies affected by muscular dystrophy

Objective:

Pregnancies in women affected by a muscular dystrophy are at an increased risk of adverse maternal and neonatal outcomes due to the effect of the disease on the muscular, cardiac and respiratory systems. We sought to evaluate the risk of adverse outcomes within a large population-based cohort study.

Methods:

We used the data extracted from the Nationwide Inpatient Sample (NIS) to conduct a retrospective population-based cohort study consisting of over 12 million births that occurred in the United States between 1999 and 2013. Births to mothers with muscular dystrophy were identified using the International Classification of Diseases, Ninth Revision (ICD-9) codes and were compared with births to mothers with no maternal muscular dystrophy. Unconditional logistic regression analysis was used to evaluate the adjusted effect of muscular dystrophy on maternal and neonatal outcomes.

Results:

During the 14-year study period, there was an increasing trend in the incidence of muscular dystrophy, with a cumulative incidence of 7.26 in 100,000 births. Women with muscular dystrophy and their neonates were at a significantly increased risk of adverse pregnancy outcomes: specifically, an increased risk of preeclampsia, preterm premature rupture of membranes, preterm labor, venous thromboembolism, cardiac dysrhythmia, requiring a blood transfusion and giving birth by cesarean section. Neonates born to affected mothers were at a significantly higher risk of being born preterm, with a congenital malformation and suffering intrauterine growth restriction.

Conclusion:

The risk of several adverse maternal and neonatal outcomes is increased in pregnant women with muscular dystrophy. As such, additional surveillance in order to mitigate the risk of adverse outcomes is warranted in these pregnancies.

Myotonic dystrophy type 2 and modifier genes: an update on clinical and pathomolecular aspects

Myotonic dystrophy (DM) is the most common adult muscular dystrophy, characterized by autosomal dominant progressive myopathy, myotonia, and multiorgan involvement. To date, two distinct forms caused by similar mutations in two different genes have been identified: myotonic dystrophy type 1 (DM1) and myotonic dystrophy type 2 (DM2). Aberrant transcription and mRNA processing of multiple genes due to RNA-mediated toxic gain-of function has been suggested to cause the complex phenotype in DM1 and DM2. However, despite clinical and genetic similarities, DM1 and DM2 may be considered as distinct disorders. This review is an update on the latest findings specific to DM2, including explanations for the differences in clinical manifestations and pathophysiology between the two forms of myotonic dystrophies.

The Impact of Pregnancy on Myotonic Dystrophy: A Registry-Based Study

BACKGROUND

The rate of symptom progression during pregnancy in myotonic dystrophy (DM) is not currently known. Further, there is little data regarding the rate of pregnancy complications and neonatal outcomes in DM.

OBJECTIVE

This study assesses symptom progression and complication rates during pregnancy in women with DM.

METHODS

DM women completed surveys regarding their prior pregnancies. Participants identified complications during their pregnancies and completed the Myotonic Dystrophy Health Index-Short Form (MDHI-SF) to measure their disease burden and identify the severity of select symptoms six-months prior to, during, and six-months after their first pregnancy.

RESULTS

152 women with DM reported on 375 pregnancies. Among these pregnancies, there was a 32.5% miscarriage rate. Some complications were common including: pre-term labor (27.8%), pre-eclampsia (10.4%), and peripartum hemorrhage (13.9%). Participants' perception of their mobility and ability to perform activities, as measured by the MDHI-SF, worsened during pregnancy and did not recover during the post-partum period.

DISCUSSION

Miscarriage, maternal disease progression during pregnancy, and other pregnancy related complications may occur in DM. Women with DM should be counseled on these potential risks prior to considering pregnancy.

Myotonic Dystrophy Type 2: An Update on Clinical Aspects, Genetic and Pathomolecular Mechanism

Myotonic dystrophy (DM) is the most common adult muscular dystrophy, characterized by autosomal dominant progressive myopathy, myotonia and multiorgan involvement. To date two distinct forms caused by similar mutations have been identified. Myotonic dystrophy type 1 (DM1, Steinert's disease) is caused by a (CTG)n expansion in DMPK, while myotonic dystrophy type 2 (DM2) is caused by a (CCTG)n expansion in CNBP. Despite clinical and genetic similarities, DM1 and DM2 are distinct disorders. The pathogenesis of DM is explained by a common RNA gain-of-function mechanism in which the CUG and CCUG repeats alter cellular function, including alternative splicing of various genes. However additional pathogenic mechanism like changes in gene expression, modifier genes, protein translation and micro-RNA metabolism may also contribute to disease pathology and to clarify the phenotypic differences between these two types of myotonic dystrophies.This review is an update on the latest findings specific to DM2, including explanations for the differences in clinical manifestations and pathophysiology between the two forms of myotonic dystrophies.

Pregnancy and delivery in women with Pompe disease

BACKGROUND

The obstetric risk in patients with Pompe disease (glycogen storage disease type II), a mainly skeletal muscle disorder, is unknown.

METHODS

The clinical course and the outcome of pregnancy, and the effect of pregnancy on disease manifestations or clinical signs and symptoms in Pompe disease were analyzed retrospectively using a questionnaire. Participating women with Pompe disease were recruited by the German and the UK sections of the International Pompe Association, and by centers associated within the German Pompe Group. The data was compared with information from the German statistical almanac, perinatal registry, and perinatal quality survey.

RESULTS

66 of 136 women responded to the questionnaire (median age: 47 years, range: 18-74). In 10 of 52 women who had been pregnant, the symptoms of Pompe disease were present during pregnancy (n=7 1st, n=1 2nd, n=1 3rd pregnancy). Muscle weakness worsened in 3 women, and first presented in 3 others during the first pregnancy (4.5% each). Respiratory problems deteriorated in 2/10 women during pregnancy. These 10 symptomatic women had 17 pregnancies (15 deliveries, 2 miscarriages, no abortions). The 42 asymptomatic women (63.6%) had 109 pregnancies (72.4% deliveries, 19.3% miscarriages, 7.3% abortions). There were no significant differences between the mean duration of pregnancies or the mean birth weight in symptomatic and asymptomatic women, or compared to the data from the general population. The same was true of pregnancy and delivery complications (including Cesarean section).

CONCLUSIONS

Our data show that women with Pompe disease do not appear to have an increased risk of pregnancy or delivery complications. However, muscle weakness and respiratory complications might manifest or worsen during pregnancy in some women.

Neurology of pregnancy

Pregnancy creates alterations in maternal physiology which predispose to unique neurologic disorders. Pre-eclampsia, eclampsia, certain types of ischemic and hemorrhagic stroke, reversible cerebral vasoconstriction syndrome, posterior reversible encephalopathy syndrome, and thunderclap headache all appear to share a common origin from vascular endothelial dysfunction, with overlapping clinical presentations. Multiple sclerosis often improves during pregnancy. Compression mononeuropathies may occur in the extremities. Myasthenia gravis may affect second stage labor. Various inflammatory peripheral neuropathies, dystrophies, myopathies may occur during pregnancy. The safety of specific immune suppressants is reviewed. Epilepsy does not have a significant effect upon the course of pregnancy, albeit there is a modest increase in the need for cesarean section. Certain antiepileptic drugs may produce fetal malformations, most notably valproic acid. Brain tumors are rare during pregnancy, but may increase in size due to activation of hormonal receptors on tumor cells surfaces, water retention, and engorged blood vessels.

The genetics and implications of neuromuscular diseases in pregnancy

Neuromuscular diseases can have a tremendous impact on pregnant women and affect offspring. Healthcare providers need to have a firm understanding of the genetics involved as well as the potential complications that can arise when treating pregnant women who have been diagnosed with a neuromuscular disease or have an increased risk for delivering an infant affected by one of these disorders. This article provides a comprehensive synopsis of genetics, including the strategies for obtaining a detailed patient and family genetic history through construction of a pedigree, as well as imparting some key knowledge for providing appropriate counseling and treatment to affected individuals and families. It addresses the genetic testing, diagnosis, impact, and medical considerations for both patients and offspring affected by myotonic dystrophy, Duchenne and Becker muscular dystrophies, limb-girdle muscular dystrophy, Charcot-Marie-Tooth disease, and spinal muscular atrophy.

Couples at risk for spinocerebellar ataxia type 2: the Cuban prenatal diagnosis experience

Cuba reports the highest worldwide prevalence of spinocerebellar ataxia type 2 (SCA2) and the greatest number of descendants at risk. A protocol for genetic counseling, presymptomatic testing, and prenatal diagnosis of hereditary ataxias has been under development since 2001. Considering that the revision of the experience with prenatal diagnosis for SCA2 in Cuba would enable comparison of ours with international findings, we designed a descriptive study, based on the retrospective revision of the medical records belonging to the 58 couples that requested their inclusion in the program, during an 11-year period (2001-2011). Most of the participants in the prenatal diagnosis program were known presymptomatic carriers, diagnosed through the presymptomatic testing in the same period of study, for an uptake among them of 22.87 % (51 out of 223). In 28 cases, the fetuses were carriers, 20 of these couples (71.43 %) decided to terminate the pregnancy; the rest continued the pregnancy to term, this resulting in a predictive test for their unborn children. A predominance of females as the at-risk progenitor was observed. Except for a slightly lower average age, the results attained in the Cuban SCA2 prenatal diagnosis program resulted similar to the ones reported for Huntington disease in other countries. It is necessary to have easy access to the Cuban program through its expansion to other genetic centers along the island. Future research is needed to evaluate the long-term impact of both the predictive testing in unborn children and the selection of other reproductive options by the at-risk couples.

Pregnancy course and outcome in women with hereditary neuromuscular disorders: comparison of obstetric risks in 178 patients

OBJECTIVE

Information about pregnancy and delivery in hereditary neuromuscular disorders (NMD) is limited and largely restricted to small case series and single case reports. Further data of obstetric histories in clinically and genetically defined subgroups are required.

STUDY DESIGN

We reviewed the obstetric histories of 178 patients with myotonic dystrophy type 1 (DM1) and 2 (DM2), Charcot-Marie-Tooth disease (CMT), spinal muscular atrophy (SMA), limb-girdle muscular dystrophy (LGMD), facioscapulohumeral muscular dystrophy (FSHD), and congenital myopathy (CM) by means of questionnaires and medical reports. Patients were recruited in the period 1992-2010 after they had at least completed one pregnancy. A total of 380 pregnancies resulting in 315 children were documented.

RESULTS

Compared to the normal German population, the number of miscarriages and hypertensive diseases in pregnancy was not increased in the cohort. Patients with NMD delivered more frequently by vaginal operations (8.9-18.2%) and by cesarean births with significantly high rates in DM1 (36.7%) and SMA (42.4%). Preterm deliveries were recorded in 30.7% of DM1, 12.6% of DM2, and 29.4% of SMA gestations. Abnormal fetal presentation occurred significantly more frequently in DM1 (34.6%) and LGMD (26.7%) deliveries and was a feature of chairbound patients. Considering a possible influence of pregnancy on the disease course, about half of LGMD, one-third of SMA, and one fifth of CMT patients reported a deterioration of symptoms in pregnancy. Neonatal outcome was favorable in all NMD but DM1, where infantile morbidity and mortality is often but not exclusively related to congenitally affected children.

CONCLUSION

Our data are important for obstetric care and genetic counseling of women with NMD who are contemplating pregnancy.

Myotonic dystrophy types 1 and 2

Myotonic dystrophies (dystrophia myotonica, or DM) are inherited disorders characterized by myotonia and progressive muscle degeneration, which are variably associated with a multisystemic phenotype. To date, two types of myotonic dystrophy, type 1 (DM1) and type 2 (DM2), are known to exist; both are autosomal dominant disorders caused by expansion of an untranslated short tandem repeat DNA sequence (CTG)(n) and (CCTG)(n), respectively. These expanded repeats in DM1 and DM2 show different patterns of repeat-size instability. Phenotypes of DM1 and DM2 are similar but there are some important differences, most conspicuously in the severity of the disease (including the presence or absence of the congenital form), muscles primarily affected (distal versus proximal), involved muscle fiber types (type 1 versus type 2 fibers), and some associated multisystemic phenotypes. The pathogenic mechanism of DM1 and DM2 is thought to be mediated by the mutant RNA transcripts containing expanded CUG and CCUG repeats. Strong evidence supports the hypothesis that sequestration of muscle-blind like (MBNL) proteins by these expanded repeats leads to misregulated splicing of many gene transcripts in corroboration with the raised level of CUG-binding protein 1. However, additional mechanisms, such as changes in the chromatin structure involving CTCN-binding site and gene expression dysregulations, are emerging. Although treatment of DM1 and DM2 is currently limited to supportive therapies, new therapeutic approaches based on pathogenic mechanisms may become feasible in the near future.

Uncommon features in Cuban families affected with Friedreich ataxia

This report describes two families who presented with autosomal recessive ataxia. By means of Polymerase Chain Reaction (PCR) molecular testing we identified expansions in the gene encoding Frataxin (FTX) that is diagnostic of Friedreich ataxia. A history of reproductive loss in the two families, prominent scoliosis deformity preceding the onset of ataxic gait, the presence of a sensitive axonal neuropathy, as well as the common origin of ancestors are unusual features of these families. These cases illustrate the importance of molecular diagnosis in patients with a recessive ataxia. The origin of the expanded gene and the GAA repeat size in the normal population are issues to be further investigated. The molecular diagnosis of Friedreich ataxia is now established in Cuba.

Myotone Dystrophien – und ihre Differenzialdiagnosen

1909 wurde die klassische myotone Dystrophie (DM1) von Steinert erstmals beschrieben, 1994 entdeckte Ricker eine 2. Form (DM2). Als genetische Ursache der DM1 wurde 1992 ein abnorm expandiertes CTG(Cytosin-Thymin-Guanin)-Triplett-Repeat im 3’-UTR des Dystrophia-myotonica-Proteinkinase-Gens (DMPK-Gen) auf Chromosom 19 entdeckt, während 2001 die DM2 auf ein abnorm expandiertes Tetranukleotid-CCTG-Repeat im Intron 1 des Zinkfinger-9-Gens (ZNF-9) auf Chromosom 3q zurückgeführt werden konnte. Multisystemische Symptome betreffen Skelettmuskulatur, Gehirn, Auge, Herz und Endokrinium. Der heterogenen Ätiologie mit 2 genetischen Loci liegt pathogenetisch eine RNA-Prozessierungsstörung mit Fehlregulation und alternativem Spleißen von organspezifisch exprimierter Genen zugrunde (so genanntes Konzept der Spleißopathie). Zusätzliche Störungen des RNA-Metabolismus sind inzwischen evident. Unsere Übersicht umfasst aktuelle Aspekte des Phänotyps, der Differenzialdiagnose, der molekularen Diagnostik, der RNA-Pathogenese sowie symptomatischer und molekularer Therapieoptionen.

RNA-dominant diseases

Several examples have come to light in which mutations in non-protein-coding regions give rise to a deleterious gain-of-function by non-coding RNA. Expression of the toxic RNA is associated with formation of nuclear inclusions and late-onset degenerative changes in brain, heart or skeletal muscle. In the best studied example, myotonic dystrophy, it appears that the main pathogenic effect of the toxic RNA is to sequester binding proteins and compromise the regulation of alternative splicing. This review describes some of the recent advances in understanding the pathophysiology of RNA-dominant diseases.

Myotonic dystrophies type 1 and 2: a summary on current aspects

Myotonic dystrophies (DMs) encompass at least 2 forms: myotonic dystrophy type 1 and 2. In general, DMs are late-onset autosomal dominant disorders characterized by a variety of multisystemic features including myotonia, muscular dystrophy, cardiac conduction defects, dilated cardiomyopathy, posterior iridescent cataracts, frontal balding, insulin-resistance and disease-specific serological abnormalities such as gamma-glutamyltransferase and creatine kinase elevations, hyperglycemia, hypotestosteronism, and reduced immunoglobulin (Ig) G and IgM levels. Beyond the adult forms, in the classic DM1, a congenital form and an early-onset form is recognized. Here we summarize current aspects of the myotonic dystrophy pathogenesis and review the core features of both types of myotonic dystrophies, including the congenital DM1.

Neuromuscular disorders in pregnancy

Many neuromuscular conditions occur more frequently during pregnancy and include carpal tunnel syndrome, Bell's palsy, lumbosacral radiculopathy, meralgia paresthetica, intercostal neuralgia, and other compression neuropathies. Preexisting or coincident neuromuscular diseases, including demyelinating polyneuropathies, inflammatory muscle disease, myasthenia gravis, and inherited nerve and muscle disease present specific problems during pregnancy. We review management of neuromuscular disorders during pregnancy, labor, delivery, and the early postpartum period.