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

Cancer Risk in Patients With Muscular Dystrophy and Myotonic Dystrophy: A Register-Based Cohort Study

BACKGROUND AND OBJECTIVES

Muscular dystrophies and myotonic disorders are genetic disorders characterized by progressive skeletal muscle degeneration and weakness. Epidemiologic studies have found an increased cancer risk in myotonic dystrophy, although the cancer risk spectrum is poorly characterized. In patients with muscular dystrophy, the cancer risk is uncertain. We aimed to determine the overall cancer risk and cancer risk spectrum in patients with muscular dystrophy and myotonic dystrophy using data from the Swedish National registers.

METHODS

We performed a matched cohort study in all patients with muscular dystrophy or myotonic dystrophy born in Sweden 1950-2017 and 50 matched comparisons by sex, year of birth, and birth county per individual. The association with cancer overall and specific malignancies was estimated using stratified Cox proportional hazard models.

RESULTS

We identified 2,355 and 1,968 individuals with muscular dystrophy and myotonic dystrophy, respectively. No increased overall cancer risk was found in muscular dystrophy. However, we observed an increased risk of astrocytomas and other gliomas during childhood (hazard ratio [HR] 8.70, 95% CI 3.57-21.20) and nonthyroid endocrine cancer (HR 2.35, 95% CI 1.03-5.34) and pancreatic cancer (HR 4.33, 95% CI 1.55-12.11) in adulthood. In myotonic dystrophy, we found an increased risk of pediatric brain tumors (HR 3.23, 95% CI 1.16-9.01) and an increased overall cancer risk in adults (HR 2.26, CI 1.92.2.66), specifically brain tumors (HR 10.44, 95% CI 7.30-14.95), thyroid (HR 3.92, 95% CI 1.70-9.03), and nonthyroid endocrine cancer (HR 7.49, 95% CI 4.47-12.56), endometrial (HR 8.32, 95% CI 4.22-16.40), ovarian (HR 4.00, 95% CI 1.60-10.01), and nonmelanoma skin cancer (HR 3.27, 95% CI 1.32-8.13).

DISCUSSION

Here, we analyze the cancer risk spectrum of patients with muscular dystrophy and myotonic dystrophy. To the best of our knowledge, this is the first report of an increased risk for CNS tumors in childhood and adult nonthyroid endocrine and pancreatic cancer in muscular dystrophy. Furthermore, for myotonic dystrophy, we confirmed previously reported associations with cancer and expanded the cancer spectrum, finding an unreported increased risk for nonthyroid endocrine cancer. Additional studies confirming the cancer risk and delineating the cancer spectrum in different genetic subtypes of muscular dystrophies are warranted before considering altered cancer screening recommendations than for the general population.

An Unusual Case of Hybrid Odontogenic Tumor in Type 1 Myotonic Dystrophy Patient

Myotonic dystrophy, also referred myotonic muscular dystrophy, is an autosomal dominant, slowly progressive, multisystem disease characterized by skeletal muscle weakness, wasting, and myotonia. A hybrid tumor of odontogenic apparatus is a lesion showing combined histopathological characteristics of two or more previously recognized odontogenic tumors and/or cysts of different categories. We, therefore, report a case of hybrid tumor (adenomatoid odontogenic tumor associated with calcifying cystic odontogenic tumor) in a myotonic dystrophic patient.

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.

Intergenerational Influence of Gender and the DM1 Phenotype of the Transmitting Parent in Korean Myotonic Dystrophy Type 1

Myotonic dystrophy type 1 (DM1) is the most common autosomal-dominant disorder caused by the CTG repeat expansion of the DMPK, and it has been categorized into three phenotypes: mild, classic, and congenital DM1. Here, we reviewed the intergenerational influence of gender and phenotype of the transmitting parent on the occurrence of Korean DM1. A total of 44 parent–child pairs matched for the gender of the transmitting parent and the affected child and 29 parent–child pairs matched for the gender and DM1 phenotype of the transmitting parent were reviewed. The CTG repeat size of the DMPK in the affected child was found to be significantly greater when transmitted by a female parent to a female child (DM1-FF) (median, 1309 repeats; range, 400–2083) than when transmitted by a male parent to a male child (650; 160–1030; p = 0.038 and 0.048 using the Tukey HSD and the Bonferroni test) or by a male parent to a female child (480; 94–1140; p = 0.003). The difference in the CTG repeat size of the DMPK between the transmitting parent and the affected child was also lower when transmitted from a male parent with classic DM1 (−235; −280 to 0) compared to when it was transmitted from a female parent with mild DM1 (866; 612–905; p = 0.015 and 0.019) or from a female parent with classic DM1 (DM1-FC) (605; 10–1393; p = 0.005). This study highlights that gender and the DM1 phenotype of the transmitting parent had an impact on the CTG repeat size of the DMPK in the affected child, with greater increases being inherited from the DM1-FF or DM1-FC situations in Korean DM1.

Cutaneous findings in myotonic dystrophy

Myotonic dystrophy types 1 and 2 are a group of complex genetic disorders resulting from the expansion of (CTG)_n nucleotide repeats in the DMPK gene. In addition to the hallmark manifestations of myotonia and skeletal muscle atrophy, myotonic dystrophy also affects a myriad of other organs including the heart, lungs, as well as the skin. The most common cutaneous manifestations of myotonic dystrophy are early male frontal alopecia and adult-onset pilomatricomas. Myotonic dystrophy also increases the risk of developing malignant skin diseases such as basal cell carcinoma and melanoma. To aid in the diagnosis and treatment of myotonic dystrophy related skin conditions, it is important for the dermatologist to become cognizant of the common and rare cutaneous manifestations of this genetic disorder. We performed a PubMed search using the key terms “myotonic dystrophy” AND “cutaneous” OR “skin” OR “dermatologic” AND “manifestation” OR “finding.” The resulting publications were manually reviewed for additional relevant publications, and subsequent additional searches were performed as needed, especially regarding the molecular mechanisms of pathogenesis. In this review, we aim to provide an overview of myotonic dystrophy types 1 and 2 and summarize their cutaneous manifestations as well as potential mechanisms of pathogenesis.

High Prevalence and Gender-Related Differences of Gastrointestinal Manifestations in a Cohort of DM1 Patients: A Perspective, Cross-Sectional Study

Myotonic dystrophy type 1 (DM1, MIM #160900), the most common muscular dystrophy among adults, is a multisystem disorder, which affects, besides the skeletal muscle, several other tissues and/or organs, including the gastrointestinal apparatus, with manifestations that frequently affect the quality of life of DM1 patients. So far, only few, mainly retrospective studies evaluated this specific topic in DM1, so we performed a perspective study, enrolling 61 DM1 patients who underwent an extensive diagnostic protocol, including administration of the Gastrointestinal Symptom Rating Scale (GSRS), a validated patient-reported questionnaire about GI symptoms, laboratory tests, liver US scan, and an intestinal permeability assay, in order to characterize frequency and assess correlations regarding specific gastrointestinal manifestations with demographic or other DM1-related features. Our results in our DM1 cohort confirm the high frequency of various gastrointestinal manifestations, with the most frequent being constipation (45.9%). γGT levels were pathologically increased in 65% of DM1 patients and GPT in 29.82%; liver ultrasound studies showed steatosis in 34.4% of patients. Significantly, 91.22% of DM1 patients showed signs of altered intestinal permeability at the specific assay. We documented a gender-related prevalence and severity of gastrointestinal manifestations in DM1 females compared to DM1 males, while males showed higher serum GPT and γGT levels than females. Correlation studies documented a direct correlation between severity of muscle weakness estimated by MIRS score and γGT and alkaline phosphatase levels, suggesting their potential use as biomarkers of muscle disease severity in DM1.

Mutation analysis of multiple pilomatricomas in a patient with myotonic dystrophy type 1 suggests a DM1-associated hypermutation phenotype

Myotonic dystrophy type 1 (DM1) is an inherited neuromuscular disease which results from an expansion of repetitive DNA elements within the 3' untranslated region of the DMPK gene. Some patients develop multiple pilomatricomas as well as malignant tumors in other tissues. Mutations of the catenin-β gene (CTNNB1) could be demonstrated in most non-syndromic pilomatricomas. In order to gain insight into the molecular mechanisms which might be responsible for the occurrence of multiple pilomatricomas and cancers in patients with DM1, we have sequenced the CTNNB1 gene of four pilomatricomas and of one pilomatrical carcinoma which developed in one patient with molecularly proven DM1 within 4 years. We further analyzed the pilomatrical tumors for microsatellite instability as well as by NGS for mutations in 161 cancer-associated genes. Somatic and independent point-mutations were detected at typical hotspot regions of CTNNB1 (S33C, S33F, G34V, T41I) while one mutation within CTNNB1 represented a duplication mutation (G34dup.). Pilomatricoma samples were analyzed for microsatellite instability and expression of mismatch repair proteins but no mutated microsatellites could be detected and expression of mismatch repair proteins MLH1, MSH2, MSH6, PMS2 was not perturbed. NGS analysis only revealed one heterozygous germline mutation c.8494C>T; p.(Arg2832Cys) within the ataxia telangiectasia mutated gene (ATM) which remained heterozygous in the pilomatrical tumors. The detection of different somatic mutations in different pilomatricomas and in the pilomatrical carcinoma as well as the observation that the patient developed multiple pilomatricomas and one pilomatrical carcinoma over a short time period strongly suggest that the patient displays a hypermutation phenotype. This hypermutability seems to be tissue and gene restricted. Simultaneous transcription of the mutated DMPK gene and the CTNNB1 gene in cycling hair follicles might constitute an explanation for the observed tissue and gene specificity of hypermutability observed in DM1 patients. Elucidation of putative mechanisms responsible for hypermutability in DM1 patients requires further research.

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.

Reproductive Cancer Risk Factors in Women With Myotonic Dystrophy (DM): Survey Data From the US and UK DM Registries

Introduction: Recent evidence demonstrates that women with myotonic dystrophy type 1 are at increased risk of reproductive organ tumors. However, studies of reproductive cancer risk factors in those patients are lacking.

Methods: Using questionnaires, we collected and analyzed personal history information related to cancer risk factors from women enrolled in a UK and US registry for myotonic dystrophy (dystrophia myotonica; DM) patients.

Results: The survey was completed by 242 DM type 1 (DM1) and 44 DM type 2 (DM2) women enrolled in the UK Registry (N = 124) and the US National Registry (N = 162). The mean age at DM1 diagnosis was 33.8 years (standard deviation, SD = 13.2) and for DM2 was 49.2 (SD = 13.0). Mean age at survey was 48.7 (SD = 12.8) and 59.1 years (SD = 12.8) for DM1 and DM2, respectively. There were no statistically significant differences between DM1 and DM2 regarding menstrual history or fertility-related factors. Yet, women with DM2 were more likely to have used menopausal hormone therapy (HT) than women with DM1 (52.3 vs. 22.1%, p < 0.0001), and more women with DM2 had a hysterectomy (53.5 vs. 29.5%, p < 0.01). These differences were not statistically significant after age adjustment (OR = 2.00, p = 0.08, and OR = 1.40, p = 0.38, respectively). The frequency of self-reported reproductive organ tumors was not significantly different comparing DM1 to DM2 (p = 0.28). However, the data suggested that women with DM2 appear to have a lower risk of malignant tumors compared to those with DM1 (OR = 0.72, p = 0.69).

Discussion: Our study is the first to characterize a wide range of reproductive risk factors in women with DM. We observed no significant differences between DM1 and DM2 in the factors that were evaluated, which suggests that the known excesses of ovarian and endometrial cancer previously reported in women with DM1 cannot be attributed to greater prevalence of standard cancer-related reproductive risk factors. Larger studies evaluating the possible link between reproductive cancer risk factors and risk of tumors in women with DM are needed.

Benign tumors in myotonic dystrophy type I target disease-related cancer sites

Objectives

Recent evidence showed that myotonic dystrophy type I (DM1) patients are at increased risk of certain cancers, but the risk of benign tumors is unknown. We compared the risk of benign tumors in DM1 patients with matched DM1‐free individuals and assessed the association between benign tumors and subsequent cancers.

Methods

We identified 927 DM1 patients and 13,085 DM1‐free individuals matched on gender, birth‐year, clinic, and clinic‐registration year from the UK Clinical Practice Research Datalink, a primary care records database. We used Cox regression models for statistical analyses.

Results

DM1 patients had elevated risks of thyroid nodules (Hazard Ratio [HR] = 10.4; 95% Confidence Interval [CI] = 3.91–27.52; P < 0.001), benign tumors of the brain or nervous system (HR = 8.4; 95% CI = 2.48–28.47; P < 0.001), colorectal polyps (HR = 4.3; 95% CI = 1.76–10.41; P = 0.001), and possibly uterine fibroids (HR = 2.7; 95% CI = 1.22–5.88; P = 0.01). Pilomatricomas and salivary gland adenomas occurred almost exclusively in DM1 patients (Fisher's exact P < 0.001). The HR for colorectal polyps was elevated in DM1 males but not in females (HR = 8.2 vs. 1.3, respectively; P‐heterogeneity < 0.001), whereas endocrine and brain tumors occurred exclusively in females. The data suggested an association between benign tumors and subsequent cancer in classic DM1 patients (HR = 2.7; 95% CI = 0.93–7.59; P = 0.07).

Interpretation

Our study showed a similar site‐specific benign tumor profile to that previously reported for DM1‐associated cancers. The possible association between benign tumors and subsequent cancer in classic DM1 patients warrants further investigation as it may guide identifying patients at elevated risk of cancer. Our findings underscore the importance of following population‐based screening recommendations in DM1 patients, for example, for colorectal cancer.

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.

Systematic thyroid screening in myotonic dystrophy: link between thyroid volume and insulin resistance

Background

Myotonic dystrophy (DM1), a neuromuscular disease related to DMPK gene mutations, is associated to endocrine disorders and cancer. A routine endocrine work-up, including thyroid ultrasound (US), was conducted in 115 genetically-proven DM1 patients in a neuromuscular reference center. The aim of this study was to determine the prevalence and the causes of US thyroid abnormalities in DM1.

Results

In the whole population (age 45.1 ± 12.2 years, 61.7% female), palpable nodules or goiters were present in 29.2%. The percentage of US goiter (thyroid volume > 18 mL) and US nodules were, respectively, 38.3 and 60.9%. Sixteen of the 115 patients had a thyroidectomy, after 22 fine-needle aspiration cytology guided by thyroid imaging reporting and data system (TIRADS) classification. Six micro- (1/6 pT3) and 3 macro-papillary thyroid carcinoma (PTCs) (2/3 intermediate risk) were diagnosed (7.9% of 115). Thyroid US led to the diagnosis of 4 multifocal and 2 unifocal (including 1 macro-PTC) non-palpable PTCs. Ultrasound thyroid volume was positively correlated to body mass index (BMI) (p = 0.015) and parity (p = 0.036), and was inversely correlated to TSH (p < 0.001) and vitamin D levels (p = 0.023). The BMI, the frequencies of glucose intolerance and PTC were significantly higher in UsGoiter versus non-UsGoiter groups.

Conclusion

In this systematically screened DM1 cohort, the frequency of UsGoiter, mainly associated to BMI, was about 40%, US nodules 60%, thyroidectomies 13–14%, and PTCs 8%, two-thirds of them being micro-PTCs with good prognosis. Therefore, a systematic screening remains debatable. A targeted US screening in case of clinical abnormality or high BMI seems more appropriate.

Electronic supplementary material

The online version of this article (10.1186/s13023-019-1019-3) contains supplementary material, which is available to authorized users.

Cancer Risk in Myotonic Dystrophy Type I: Evidence of a Role for Disease Severity

Background

Myotonic dystrophy type 1 (DM1) is an inherited trinucleotide repeat disorder in which specific cancers have been implicated as part of the disease phenotype. This study aimed to assess whether cancer risk in DM1 patients is modified by disease severity.

Methods

Using the United Kingdom Clinical Practice Research Datalink (primary care electronic medical records), we identified a cohort of 927 DM1 and a matched cohort of 13 085 DM1-free individuals between January 1, 1988 and February 29, 2016. We used Cox regression models to calculate the hazard ratios (HRs) and 95% confidence intervals (CIs) of organ-specific cancer risks. Analyses were stratified by age at DM1 diagnosis as a surrogate for disease severity. Statistical tests were two-sided.

Results

Patients with classic DM1 (age at diagnosis: 11-40 years) were at elevated risk of cancer overall (HR = 1.81; 95% CI = 1.12 to 2.93); cancers of the thyroid (HR = 15.93; 95% CI = 2.45 to 103.64), uterus (HR = 26.76; 95% CI = 2.32 to 309.26), and cutaneous melanoma (HR = 5.98; 95% CI = 1.24 to 28.79) accounted for the excess. In late-onset DM1 patients (age at diagnosis >40 years), a reduced overall cancer risk was observed (HR = 0.53; 95% CI = 0.32 to 0.85), possibly driven by the deficit in hematological malignancies (DM1 = 0 cases, DM1-free = 54 cases; P = .02). The difference between the observed HR for classic and late-onset DM1 was statistically significant (P < .001).

Conclusions

The observed difference in relative cancer risk between classic and late-onset DM1 patients compared with their DM1-free counterparts provides the first evidence that disease severity modifies DM1-related cancer susceptibility. This novel finding may guide clinical management and scientific investigations for the underlying molecular mechanisms in DM-related carcinogenesis.

Risk of skin cancer among patients with myotonic dystrophy type 1 based on primary care physician data from the U.K. Clinical Practice Research Datalink

Myotonic dystrophy type 1 (DM1) is an inherited multisystem neuromuscular disorder caused by a CTG trinucleotide repeat expansion in the DMPK gene. Recent evidence documents that DM1 patients have an increased risk of certain cancers, but whether skin cancer risks are elevated is unclear. Using the U.K. Clinical Practice Research Datalink (CPRD), we identified 1,061 DM1 patients and 15,119 DM1-free individuals matched on gender, birth year (±2 years), attending practice and registration year (±1 year). We calculated the hazard ratios (HRs) and 95% confidence intervals (CIs) for the association of DM1 diagnosis with skin cancer risk using Cox proportional hazards models, for all skin cancers combined and by histological subtype. Follow-up started at the latest of the age at practice registration, DM1 diagnosis/control selection or January 1st 1988, and ended at the earliest of the age at first skin cancer diagnosis, death, transfer out of the practice, last date of data collection or the end of the CPRD record (October 31, 2016). During a median follow-up of 3.6 years, 35 DM1 patients and 108 matched DM1-free individuals developed a skin cancer. DM1 patients had an increased risk of skin cancer overall (HR = 5.44, 95% CI = 3.33-8.89, p < 0.0001), and basal cell carcinoma (BCC) (HR = 5.78, 95% CI = 3.36-9.92, p < 0.0001). Risks did not differ by gender, or age at DM1 diagnosis (p-heterogeneity > 0.5). Our data confirm suggested associations between DM1 and skin neoplasms with the highest risk seen for BCC. Patients are advised to minimize ultraviolet light exposure and seek medical advice for suspicious lesions.

Imaging of the thymus in myotonic dystrophy type 1

The occurrence of thymoma in myotonic dystrophy type 1 (DM1) has been occasionally reported, and an increased risk of tumors has been observed. We performed imaging of the thymus in 22 patients carrying DMPK expansion. Clinical examination and routine instrumental exams were performed at the same time. We observed no thymic abnormalities in 13 subjects, thymic hyperplasia in eight patients, and an invasive thymoma in one case. Subjects with thymic abnormalities did not show peculiarities as regards clinical and electrophysiological features. We observed thymoma in one patient with an expansion in the higher range. Abnormalities of the thymus including hyperplasia and thymoma can be present in DM1, but do not seem to play a major role in DM1 pathogenesis. Further studies are needed to understand if some RNA splicing factors involved in DM1 and influenced by CTG expansion size could have a role in thymocytes proliferation.

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.

Cutaneous features of myotonic dystrophy types 1 and 2: Implication of premature aging and vitamin D homeostasis

Skin changes have been described in myotonic dystrophy type 1 (DM1). However, whether and in which way skin is a target of specific disease alterations in DM1 and DM2 has not been yet clarified. This study aims to explore cutaneous features of DM1 and DM2 patients. Skin examination was performed in 60 DM1, 15 DM2, and 103 control, unselected patients by means of dermoscopy. It revealed quantitative and qualitative abnormalities of nevi and typical signs of premature aging in both DM1 and DM2 patients, with a significantly higher frequency of dysplastic nevi, alopecia, xerosis and seborrheic dermatitis. Twenty-eight nevi were excised in DM patients and none showed histological features of melanoma, although 12 of them were diagnosed as dysplastic and the remaining 16 presented histological irregularity in melanin distribution. In DM1 patients, the number of nevi correlated with CTG expansion size, whereas the presence of dysplastic nevi and xerosis inversely correlated with vitamin D levels. DM1 and DM2 patients display a high frequency of skin abnormalities, the most common of which correlate with genotype severity and serum vitamin D levels. Skin examination is highly informative in these patients and reveals features suggestive of premature aging and impaired vitamin D homeostasis.