Quantifying cancer absolute risk and cancer mortality in the presence of competing events after a myotonic dystrophy diagnosis

Mortality Trends and Causes of Death in Myotonic Dystrophy Type 1 Patients From the UK Clinical Practice Research Datalink

INTRODUCTION/AIM

Patients with myotonic dystrophy type1 (DM1) have reduced lifespan. This study aimed to quantify mortality risks, and evaluate causes and time trends in DM1.

METHODS

We identified 1021 DM1 patients and 15,104 matched DM1-free controls from the United Kingdom (UK) Clinical Practice Research Datalink. We used Cox proportional hazards regression models to assess differences in all-cause or cause-specific mortality between DM1 patients and matched controls, and computed standardized mortality ratios (SMRs) for comparisons of DM1 patients with the UK general population.

RESULTS

DM1 patients were at higher risk of death compared with matched DM1-free controls (hazard ratio [HR] = 2.9, 95% confidence interval [CI] = 2.5-3.4) or the general UK population (SMR = 8.1, 95% CI = 7.3-9.1). The excess risk was primarily attributed to deaths from respiratory failure (HR = 26.7, p < 0.001), aspiration pneumonia (HR = 15.8, p < 0.001), arrythmia, and conduction defects (HR = 15.7, p < 0.001). No mortality risk difference between DM1 patients and matched DM1-free cohort was noted for all cancers combined (p = 0.52). No significant calendar time-related changes in overall survival were seen for DM1 patients (p trend = 0.19). In mortality cause-specific analysis, and compared with patients diagnosed before 1993, death from cancer was on the rise (HR = 2.35, and 5.82 for patients diagnosed 1993-2003, and 2004-2016).

DISCUSSION

Most DM1 patients died of known disease complications. This highlights the need for integrated clinical approaches with more careful and frequent monitoring.

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.

Frequency and type of cancers in myotonic dystrophy: A retrospective cross-sectional study

INTRODUCTION/AIMS

Myotonic dystrophies (DMs) are autosomal dominant diseases in which expression of a mutant expanded repeat mRNA leads to abnormal splicing of downstream effector genes thought to be responsible for their multisystem involvement. Cancer risk and cancer-related deaths are increased in DM patients relative to the general population. We aimed at determining the frequency and type of cancers in both DM1 and DM2 vs a non-DM muscular dystrophy cohort.

METHODS

A retrospective, cross-sectional study was carried out on patients with genetically confirmed DM1, DM2, facioscapulohumeral muscular dystrophy (FSHD), and oculopharyngeal muscular dystrophy (OPMD) at our institutions from 2000 to 2020.

RESULTS

One hundred eighty-five DM1, 67 DM2, 187 FSHD, and 109 OPMD patients were included. Relative to non-DM, DM patients had an increased cancer risk that was independent of age and sex. Specifically, an increased risk of sex-related (ovarian) and non-sex-related (non-melanoma skin, urological, and hematological) cancers was observed in DM1 and DM2, respectively. The length of CTG repeat expansion was not associated with cancer occurrence in the DM1 group.

DISCUSSION

In addition to current consensus-based care recommendations, our findings prompt consideration of screening for skin, urological, and hematological cancers in DM2 patients, and screening of ovarian malignancies in DM1 female patients.

Cancer and Myotonic Dystrophy

Myotonic dystrophy (DM) is the most common muscular dystrophy in adults. Dominantly inherited CTG and CCTG repeat expansions in DMPK and CNBP genes cause DM type 1 (DM1) and 2 (DM2), respectively. These genetic defects lead to the abnormal splicing of different mRNA transcripts, which are thought to be responsible for the multiorgan involvement of these diseases. In ours and others' experience, cancer frequency in patients with DM appears to be higher than in the general population or non-DM muscular dystrophy cohorts. There are no specific guidelines regarding malignancy screening in these patients, and the general consensus is that they should undergo the same cancer screening as the general population. Here, we review the main studies that investigated cancer risk (and cancer type) in DM cohorts and those that researched potential molecular mechanisms accounting for DM carcinogenesis. We propose some evaluations to be considered as malignancy screening in patients with DM, and we discuss DM susceptibility to general anesthesia and sedatives, which are often needed for the management of cancer. This review underscores the importance of monitoring the adherence of patients with DM to malignancy screenings and the need to design studies that determine whether they would benefit from a more intensified cancer screening than the general population.

Myotonic Dystrophy

PURPOSE OF REVIEW

Myotonic dystrophy type 1 (DM1) and myotonic dystrophy type 2 (DM2) are genetic disorders affecting skeletal and smooth muscle, heart, brain, eyes, and other organs. The multisystem involvement and disease variability of myotonic dystrophy have presented challenges for clinical care and research. This article focuses on the diagnosis and management of the disease. In addition, recent advances in characterizing the diverse clinical manifestations and variability of the disease are discussed.

RECENT FINDINGS

Studies of the multisystem involvement of myotonic dystrophy, including the most lethal cardiac and respiratory manifestations and their molecular underpinnings, expand our understanding of the myotonic dystrophy phenotype. Advances have been made in understanding the molecular mechanisms of both types of myotonic dystrophy, providing opportunities for developing targeted therapeutics, some of which have entered clinical trials in DM1.

SUMMARY

Continued efforts focus on advancing our molecular and clinical understanding of DM1 and DM2. Accurately measuring and monitoring the diverse and variable clinical manifestations of myotonic dystrophy in clinic and in research is important to provide adequate care, prevent complications, and find treatments that improve symptoms and life quality.

Nationwide incidence of myotonic dystrophy type 1 and the status of multi-organ involvement

PURPOSE

This study aimed to investigate the incidence of myotonic dystrophy type 1 (DM1) and the status of multi-organ involvement.

METHODS

This was a nationwide, population-based, cohort study using data from the Korean National Health Claims database. All patients with DM1 from the entire population aged ≤ 80 years were included. To identify possible systemic diseases along with DM1, we searched for concurrent codes for systemic diseases. To assess the recent status of systemic evaluation, concurrent codes for various diagnostic and treatment modalities were collected. Cumulative incidence during 2016-2019 was first evaluated then systemic evaluation for those patients was assessed during 2010-2019.

RESULTS

A total of 387 patients (47.8% men) during the recent 4-year study period (2016-2019) were diagnosed with DM1. The cumulative incidence in the general population was 0.77 (95% confidence interval: 0.76-0.77) per 100,000 persons. In newly developed incidental cases, cardiac involvement developed in 51.2%, pneumonia in 30.7%, diabetes in 26.9%, brain involvement in 18.1%, cataract in 13.7%, and cancers in 5.4% of total patients. Electrocardiography was performed in 93.8%, Holter in 33.9%, and echocardiography in 31.3% of the total patients for cardiac evaluation.

CONCLUSIONS

The incidence estimates of DM1 in the Asian population were lower than those of Caucasians. This study provides the real situation of screening and treatment for systemic diseases related to DM1. These detailed estimates could promote an understanding of the current disease status and allow for appropriate planning within the healthcare system.

Current Treatment Options for Patients with Myotonic Dystrophy Type 2

Purpose of the review

Myotonic dystrophy types 1 and 2 are frequent forms of muscular dystrophies in adulthood. Their clinical differences need to be taken into account for the most appropriate treatment of patients. The aim of this article is to provide an overview on the current and upcoming therapeutic options for patients with myotonic dystrophy type 2 (DM2).

Recent findings

At the moment, no disease-modifying therapies are available for DM2; next-generation therapies may however be available in the near future. In the meanwhile, the symptomatic management of patients has greatly improved, thank to the production of consensus-based standards of care and the growing evidence of efficacy of anti-myotonic drugs, promising employment of cannabinoids for symptom’s relief, regular monitoring, and early detection of treatable extra-muscular manifestations.

Summary

The treatment of DM2 is currently symptomatic and relies on the coordinated intervention of a multidisciplinary team. It remains to be determined whether upcoming causal therapies for myotonic dystrophy type 1 will be applicable also in DM2.

New developments in myotonic dystrophies from a multisystemic perspective

PURPOSE OF REVIEW

The multisystemic involvement of myotonic dystrophies (DMs) intricates disease monitoring, patients' care and trial design. This update of the multifaceted comorbidities observed in DMs aims to assist neurologists in the complex management of patients and to encourage further studies for still under-investigated aspects of the disease.

RECENT FINDINGS

We reviewed the most recent studies covering pathogenesis and clinical aspects of extra-muscular involvement in DM1 and DM2. The largest body of evidence regards the cardiac and respiratory features, for which experts' recommendations have been produced. Gastrointestinal symptoms emerge as one of the most prevalent complaints in DMs. The alteration of insulin signaling pathways, involved in gastrointestinal manifestations, carcinogenesis, muscle function, cognitive and endocrinological aspects, gain further relevance in the light of recent evidence of metformin efficacy in DM1. Still, too few studies are performed on large DM2 cohorts, so that current recommendations mainly rely on data gathered in DM1 that cannot be fully translated to DM2.

SUMMARY

Extra-muscular manifestations greatly contribute to the overall disease burden. A multidisciplinary approach is the key for the management of patients. Consensus-based recommendations for DM1 and DM2 allow high standards of care but further evidence are needed to implement these recommendations.

Myotonic Muscular Dystrophies

PURPOSE OF REVIEW

This article describes the clinical features, pathogenesis, prevalence, diagnosis, and management of myotonic dystrophy type 1 and myotonic dystrophy type 2.

RECENT FINDINGS

The prevalence of myotonic dystrophy type 1 is better understood than the prevalence of myotonic dystrophy type 2, and new evidence indicates that the risk of cancer is increased in patients with the myotonic dystrophies. In addition, descriptions of the clinical symptoms and relative risks of comorbidities such as cardiac arrhythmias associated with myotonic dystrophy type 1 have been improved.

SUMMARY

Myotonic dystrophy type 1 and myotonic dystrophy type 2 are both characterized by progressive muscle weakness, early-onset cataracts, and myotonia. However, both disorders have multisystem manifestations that require a comprehensive management plan. While no disease-modifying therapies have yet been identified, advances in therapeutic development have a promising future.

Diabetes, metformin and cancer risk in myotonic dystrophy type I

Myotonic dystrophy type I (DM1) is an autosomal dominant multisystem disorder characterized by myotonia and muscle weakness. Type 2 diabetes (T2D) and cancer have been shown to be part of the DM1 phenotype. Metformin, a well-established agent for the management of T2D, is thought to have cancer-preventive effects in the general population. In our study, we aimed to assess the association between T2D, metformin use and the risk of cancer in DM1 patients. We identified a cohort of 913 DM1 patients and an age-, sex- and clinic-matched cohort of 12,318 DM1-free controls from the UK Clinical Practice Research Datalink, a large primary care records database. We used Cox regression models to assess cancer risk in T2D patients who were metformin users or nonusers compared to patients without T2D. Separate analyses were conducted for DM1 patients and controls. T2D was more prevalent in DM1 than in controls (8% vs. 3%, p < 0.0001). DM1 patients with T2D, compared to those without T2D, were more likely to develop cancer (hazard ratio [HR] = 3.60, 95% confidence interval [CI] = 1.18-10.97; p = 0.02), but not if they were treated with metformin (HR = 0.43, 95% CI = 0.06-3.35; p = 0.42). Among controls, we observed no significant associations between T2D and cancer risk in either users or nonusers of Metformin (HR = 1.28, 95% CI = 0.91-1.79; p = 0.16 and HR = 1.13, 95% CI = 0.72-1.79; p = 0.59, respectively). These results show an association between T2D and cancer risk in DM1 patients and may provide new insights into the possible benefits of Metformin use in DM1.

Uveal Melanoma Associated With Myotonic Dystrophy: A Report of 6 Cases

Importance

Patients with myotonic dystrophy (MD) have an increased risk of malignancy including uveal melanoma. This case series further explores the association between these 2 diseases.

Objective

To describe a cohort of patients with uveal melanoma associated with MD, including a case of iris melanoma, and MD-associated uveal melanoma in relatives.

Design, Setting, and Participants

Retrospective case series at 3 tertiary referral centers (Wills Eye Hospital, Philadelphia, Pennsylvania; Mayo Clinic, Rochester, Minnesota; and Moorfields Eye Hospital, London, England), between January 1, 2000, and August 31, 2017. The study included 6 patients with MD and uveal melanoma.

Main Outcomes and Measures

Melanoma response to treatment and development of metastatic disease.

Results

There were 6 patients, 4 men and 2 women, with MD and uveal melanoma. The mean patient age at melanoma diagnosis was 47 years (median, 43 years; range, 30-67 years), and the tumor involved the choroid in 5 patients (83%) and iris in 1 patient (17%). The diagnosis of MD was known since young adulthood in 2 patients (33%) and was discovered in adulthood in 4 patients (67%). The main clinical features of MD included muscle weakness (n = 5; 83%), myotonia (n = 4; 67%), polychromatic cataract (n = 4; 67%), complications with general anesthesia (n = 4; 67%), myalgia (n = 3; 50%), cardiac arrhythmia (n = 2; 33%), and frontal baldness (n = 2; 33%). Genetic testing revealed MD type 1 (4 of 4 tested patients), and 2 patients demonstrated positive family history of MD with classic clinical features and preferred no testing. Melanoma treatment included plaque radiotherapy (n = 4; 67%), photodynamic therapy (n = 1; 17%), and declined treatment (n = 1; 17%). At follow-up of 6, 6, 41, 42, and 87 months (5 patients), findings included melanoma regression (4 of 5 tumors), melanoma recurrence (1 of 5 tumors), and no metastatic disease (5 of 5 patients).

Conclusions and Relevance

Six adult patients with MD demonstrated uveal melanoma involving the choroid or iris, emphasizing the association between these 2 diseases. Further research seems warranted to explore the pathogenesis of uveal melanoma in MD. These findings support the consideration of ophthalmic examination for uveal melanoma in patients with MD.

Cancer phenotype in myotonic dystrophy patients: Results from a meta-analysis

INTRODUCTION

Recent studies have provided evidence that patients with myotonic dystrophy (DM) are at excess risk of cancer. However, inconsistencies regarding affected anatomic sites persist.

METHODS

We performed a meta-analysis of cancer risk in DM, searching among studies published between January 1, 1990 and December 31, 2016. Eligible studies were full reports of DM cohorts with site-specific risks.

RESULTS

The analysis included 5 studies, comprising 2,779 patients. Risk estimates for cancers of the endometrium and cutaneous melanoma were reported in all studies. The pooled standardized incidence ratio (pSIRs) for endometrial cancer was 7.48 (95% confidence interval [CI] 4.72-11.8) and for cutaneous melanoma was 2.45 (95% CI 1.31-4.58). Among cancers reported in 4 of 5 studies, elevated risks were observed for thyroid (pSIR = 8.52, 95% CI 3.62-20.1), ovarian (pSIR = 5.56, 95% CI 2.99-10.3), testicular (pSIR = 5.95, 95% CI 2.34-15.1), and colorectal (pSIR = 2.2, 95% CI 1.39-3.49) cancers.

DISCUSSION

Our data refine the DM cancer phenotype, which may guide patient clinical management and inform plans for molecular investigations to understand DM-related carcinogenesis. Muscle Nerve 58: 517-522, 2018.

RARE POMC MUTATION IN A PATIENT WITH MYOTONIC DYSTROPHY TYPE 1 AND ADRENOCORTICOTROPIN HYPERRESPONSE TO CORTICOTROPIN-RELEASING HORMONE

Objective

Myotonic dystrophy (DM) is a monogenic disorder. It is caused by expansion of a cytosine-thymineguanine triplet in the DMPK gene which encodes for myotonic dystrophy protein kinase (DMPK).

Methods

A 24-year-old man with DM and the DMPK mutation presented with elevated adrenocorticotropic hormone (ACTH) levels twice (152 and 185 pg/mL; normal value is 10 to 52 pg/mL) with normal cortisol levels (134.6 and 113.0 ng/mL, or 371.3 and 311.7 nmol/L; normal values are 67 to 226 ng/mL or 184.8 to 623.5 nmol/L). ACTH, corticotropin-releasing hormone (CRH) and insulin tolerance test (ITT) demonstrated normal cortisol response to ACTH and partial response to CRH and ITT tests, and ACTH hyperresponse to CRH and ITT. We suspected ACTH and/or ACTH receptor (ACTHR) mutations and evaluated the genetic profile for pro-opiomelanocortin (POMC), melanocortin 2 receptor (MC2R) and follicle-stimulating hormone receptor (FSHR) genes.

Results

No mutations were found in either the MC2R or FSHR genes. The patient was heterozygous for the c.614A>G mutation corresponding to a p.53D>G substitution with a glycine instead of an aspartate in position 53 in POMC gene. This mutation was outside the sequence for ACTH (which spans amino acids 138 to 176) but was included in the part originating the N-terminal peptide of pro-opiomelanocortin (also called pro-γ-melanocyte stimulating hormone) which spans amino acids 27 to 102 and is involved in the regulation of adrenal steroidogenesis.

Conclusion

The pathologic expansion of the cytosine-thymine-guanine triplet repeat in the 3' noncoding region of DMPK could explain the hyperresponse of ACTH typical of DM. The mutation of pro-γ-melanocyte-stimulating hormone could be associated with the abnormal response of cortisol, compatible with a partial adrenal insufficiency. Other studies are necessary to demonstrate this hypothesis.

Survival patterns and cancer determinants in families with myotonic dystrophy type 1

BACKGROUND AND PURPOSE

Research indicates that patients with myotonic dystrophy type 1 (DM1) are at increased risk of cancer and early death. Family data may provide insights given DM1 phenotypic heterogeneity, the broad range of non-muscular manifestations and the usual delays in the diagnosis of DM1.

METHOD

Family history data were collected from 397 genetically and/or clinically confirmed DM1 patients (respondents) enrolled in the US or UK myotonic dystrophy registries. Standardized mortality ratios were calculated for DM1 first-degree relatives (parents, siblings and offspring) by their reported DM1 status (affected, unaffected or unknown). For cancer-related analyses, mixed effects logistic regression models were used to evaluate factors associated with cancer development in DM1 families, including familial clustering.

RESULTS

A total of 467 deaths and 337 cancers were reported amongst 1737 first-degree DM1 relatives. Mortality risk amongst relatives reported as DM1-unaffected was comparable to that of the general population [standardized mortality ratio (SMR) 0.82, P = 0.06], whilst significantly higher mortality risks were noted in DM1-affected relatives (SMR = 2.47, P < 0.0001) and in those whose DM1 status was unknown (SMR = 1.60, P < 0.0001). In cancer risk analyses, risk was higher amongst families in which the DM1 respondent had cancer (odds ratio 1.95, P = 0.0001). Unknown DM1 status in the siblings (odds ratio 2.59, P = 0.004) was associated with higher cancer risk.

CONCLUSION

There is an increased risk of death, and probably cancer, in relatives with DM1 and in those whose DM1 status is unknown. This suggests a need to perform a careful history and physical examination, supplemented by genetic testing, to identify family members at risk for DM1 and who might benefit from disease-specific clinical care and surveillance.

Benign and malignant tumors in the UK myotonic dystrophy patient registry

INTRODUCTION

In light of recent evidence indicating that cancer is part of the myotonic dystrophy (DM) phenotype, we assessed the prevalence of benign and malignant tumors among 220 patients enrolled in the UK Myotonic Dystrophy Patient Registry and evaluated factors associated with their development.

METHODS

A survey was distributed to collect tumor history and lifestyle information. We used multinomial logistic regression for the analysis.

RESULTS

Thirty-nine benign (30 patients), and 16 malignant (15 patients) tumors were reported. Increasing age (odds ratio [OR] = 1.13, 95% confidence interval [CI] = 1.05-1.21, P = 0.001) and earlier age at DM diagnosis (OR = 1.06, 95% CI = 1.00-1.13, P = 0.04) were associated with benign and malignant tumors (OR = 1.20, 95% CI = 1.10-1.30, P < 0.001 and OR = 1.08, 95% CI = 1.01-1.15, P = 0.02, respectively). Female gender was associated with benign tumors only (OR = 6.43, 95% CI = 1.79-23.04, P = 0.004). No associations were observed between tumors and smoking (P = 0.24), alcohol consumption (P = 0.50), or body mass index (P = 0.21).

DISCUSSION

Our results confirm previous findings suggesting a limited role for common lifestyle factors and a potential genetic contribution in DM tumor predisposition. Muscle Nerve 57: 316-320, 2018.

Pigmentation phenotype, photosensitivity and skin neoplasms in patients with myotonic dystrophy

BACKGROUND AND PURPOSE

Recent studies have suggested a possible excess risk of skin neoplasms in patients with myotonic dystrophy (DM). Risk factors related to this observation have not been defined.

METHOD

Information regarding personal history of skin tumors, pigmentation phenotype, and skin reaction to sun exposure were collected from 266 DM patients who were enrolled in the US National Institutes of Health National Registry of Myotonic Dystrophy and Facioscapulohumeral Muscular Dystrophy Patients and Family Members.

RESULTS

Seventy-seven subjects reported having skin tumors that were either benign (n = 31), malignant (n = 32) or both (n = 14). Female gender [odds ratio (OR) = 2.27, 95% confidence interval (CI) 1.02-5.05, P = 0.04], older age (OR = 1.10, 95% CI 1.05-1.16, P < 0.001) and DM1 subtype (OR = 3.42, 95% CI 1.27-9.26, P = 0.02) were associated with a malignant skin tumor. The associations between malignant skin tumors and known risk factors [light eye color (OR = 1.62, 95% CI 0.78-3.39, P = 0.20), light skin complexion (OR = 1.31, 95% CI 0.63-2.73, P = 0.48) and moderate/extensive face freckles (OR = 1.47, 95% CI 0.50-4.34, P = 0.49)] were modest. Strong, but not statistically significant, associations were noted with sunburn reactions when exposed to sunlight (OR = 4.28, 95% CI 0.91-19.95, P = 0.06, and OR = 2.19, 95% CI 0.67-7.09, P = 0.19, for sunburn with and without blistering, respectively).

CONCLUSIONS

Although our study was limited by small sample size, the risk factors for malignant skin tumors in DM strongly resemble the general population. It is recommended that DM patients adhere to sun exposure protective behavior.

A population-based survey of risk for cancer in individuals diagnosed with myotonic dystrophy

INTRODUCTION

The risk of cancer in patients diagnosed with myotonic dystrophy (DM) is reported for the homogeneous Utah population.

METHODS

Clinical data accessed from the largest Utah healthcare providers have been record-linked to the Utah Population Database, a population-based resource also linked to the Utah Cancer Registry. Relative risks were estimated for 36 cancers of different types in 281 DM patients.

RESULTS

Testicular cancer (relative risk [RR] = 10.74; 95% confidence interval [CI], 1.91-38.79), endometrial cancer (RR = 6.98; 95% CI, 1.24-25.22), and non-Hodgkin lymphoma (RR = 4.25; 95% CI, 1.16-12.43) were all observed at significant excess in DM patients.

CONCLUSIONS

This study confirms an overall increased risk of cancer in DM. Individuals diagnosed with DM might benefit from risk counseling. Muscle Nerve 54: 783-785, 2016.

Increased risk of tumor in DM1 is not related to exposure to common lifestyle risk factors

Recent studies documented an increased risk of neoplasm in patients with myotonic dystrophies (DM). Yet, none of these studies evaluated the contribution of common cancer risk factors in such observation. In this study, we included a cohort of patients (n = 255) with an established molecular diagnosis of DM type 1 (DM1), and who receives their treatment in one of the four centers with recognized expertise in neuromuscular disorders in Rome. We estimated the prevalence of benign and malignant tumors, and assessed if lifestyle factors and/or specific disease features would be associated to their occurrence. Overall, 59 benign tumors in 54 patients and 19 malignant tumors in 17 patients were diagnosed. The most common malignant neoplasms were cancers of the skin (31.6%), thyroid (21.0%), ovary (10.5%), and breast (10.5%). Uterine fibroid was the most common benign tumor (37.6%) in women, while pilomatricoma was the most common in men (28.6%). Age at enrollment (OR = 1.02, 95% CI 1.00-1.05), and female gender (OR = 5.71, 95% CI 2.90-11.22) were associated with tumor development in DM1 patients, while thyroid disorders was associated with malignant tumors only in women (OR = 5.12, 95% CI 1.35-19.37). There was no association between tumor development and evaluated lifestyle factors. In conclusion, the lack of association between common cancer risk factors and tumor development in DM1 support a pathogenic link between tumors and DM1 itself, emphasizing the need for a systematic surveillance. Our observation of an association between thyroid diseases in women and cancer development needs confirmation.

Brain tumors in patients with myotonic dystrophy: a population-based study

BACKGROUND AND PURPOSE

Patients with myotonic dystrophy (DM) are at high risk of brain cancer. This study describes the spectrum of brain neoplasms in DM patients.

METHODS

Data from 1119 DM patients identified from the National Swedish Patient Register between 1987 and 2007 were linked to the National Cancer and the Cause of Death Registers. Standardized incidence ratios (SIRs) and cumulative incidence to quantify the relative and absolute risks of brain neoplasms were calculated and the Kaplan-Meier estimator was used for survival analysis. Patient follow-up started at birth or the age at the start of Swedish cancer registration (1 January 1958) and ended at the age of brain neoplasm diagnosis, death or on 31 December 2007.

RESULTS

Twenty patients developed brain neoplasm during follow-up {median age 53, range 2-76 years, accounting for a five-fold excess risk of brain tumors during the patient lifetime [SIR = 5.4, 95% confidence interval (CI) 3.4-8.1, P = 1 × 10(-5) ]}. Astrocytoma was the most common histological subtype (n = 16, 80%), and almost all cases (n = 19) developed after age 20. No statistically significant differences in gender-specific risks (SIR in men 6.3 and in women 3.8, P-heterogeneity 0.46) were observed. After accounting for competing mortality related to DM, the cumulative incidence of brain neoplasms reached 2.9% (95% CI 1.8%-4.7%) by age 70. Five-year survival after brain tumor diagnosis was 52% (95%CI 29%-75%) overall (number at risk 8) and 34% (95% CI 26%-47%) for malignant neoplasms (number at risk 5).

CONCLUSION

Despite the high relative risk of DM-related brain tumors, the absolute risk is modest. Nonetheless, careful evaluation of DM patients with new central nervous system symptoms is warranted.

Muscle wasting in myotonic dystrophies: a model of premature aging

Myotonic dystrophy type 1 (DM1 or Steinert’s disease) and type 2 (DM2) are multisystem disorders of genetic origin. Progressive muscular weakness, atrophy and myotonia are the most prominent neuromuscular features of these diseases, while other clinical manifestations such as cardiomyopathy, insulin resistance and cataracts are also common. From a clinical perspective, most DM symptoms are interpreted as a result of an accelerated aging (cataracts, muscular weakness and atrophy, cognitive decline, metabolic dysfunction, etc.), including an increased risk of developing tumors. From this point of view, DM1 could be described as a progeroid syndrome since a notable age-dependent dysfunction of all systems occurs. The underlying molecular disorder in DM1 consists of the existence of a pathological (CTG) triplet expansion in the 3′ untranslated region (UTR) of the Dystrophia Myotonica Protein Kinase (DMPK) gene, whereas (CCTG)n repeats in the first intron of the Cellular Nucleic acid Binding Protein/Zinc Finger Protein 9(CNBP/ZNF9) gene cause DM2. The expansions are transcribed into (CUG)n and (CCUG)n-containing RNA, respectively, which form secondary structures and sequester RNA-binding proteins, such as the splicing factor muscleblind-like protein (MBNL), forming nuclear aggregates known as foci. Other splicing factors, such as CUGBP, are also disrupted, leading to a spliceopathy of a large number of downstream genes linked to the clinical features of these diseases. Skeletal muscle regeneration relies on muscle progenitor cells, known as satellite cells, which are activated after muscle damage, and which proliferate and differentiate to muscle cells, thus regenerating the damaged tissue. Satellite cell dysfunction seems to be a common feature of both age-dependent muscle degeneration (sarcopenia) and muscle wasting in DM and other muscle degenerative diseases. This review aims to describe the cellular, molecular and macrostructural processes involved in the muscular degeneration seen in DM patients, highlighting the similarities found with muscle aging.

Myotonic dystrophy

Myotonic dystrophy (dystrophia myotonica, DM) is one of the most common lethal monogenic disorders in populations of European descent. DM type 1 was first described over a century ago. More recently, a second form of the disease, DM type 2 was recognized, which results from repeat expansion in a different gene. Both disorders have autosomal dominant inheritance and multisystem features, including myotonic myopathy, cataract, and cardiac conduction disease. This article reviews the clinical presentation and pathophysiology of DM and discusses current management and future potential for developing targeted therapies.