An Age-Standardized Prevalence Estimate and a Sex and Age Distribution of Myotonic Dystrophy Types 1 and 2 in the Rome Province, Italy

Abstract

Background: Prevalence estimates for the 2 forms of myotonic dystrophy types 1 and 2 (DM1 and DM2) are not exhaustive or non-available. Our aim was to estimate the minimum prevalence of DM1 and DM2 in Italy in the Rome province, applying standards of descriptive epidemiology. Methods: All patients with a molecular diagnosis of DM1/DM2 and residents in the Rome province in 2013 have been enrolled, and the age-standardized prevalence has been calculated, assuming a Poisson distribution and adjusting for age. Results: We identified 395 DM1 patients: the age-standardized prevalence for total, females and males was 9.65, 8.35 and 11.07/100,000, respectively. The mean age of subjects differed considerably according to CTG repeat length (p = 0.001). Forty DM2 patients were identified. The age-standardized prevalence for total, females and males was 0.99, 1.07 and 0.90/100,000, respectively. The mean age was 57.05. Conclusions: We estimated for the first time the age-standardized prevalence and the sex and age distribution of DM1 and DM2 in a general population. A higher prevalence of males in DM1 and females in DM2 and a higher mean age of DM2 patients (+8 years) were ascertained. Prevalence of DM2 was 10% that of DM1. These prevalence values are probably lower than mutational rates due to the incomplete penetrance of DM1 mutations and to the clinical elusiveness of DM2. Our findings will be useful in designing cohort studies and for developing a disease registry.

Distribution and Structure of DM2 Repeat Tract Alleles in the German Population

“…The estimation of DM2 prevalence in Germany of about 9 in 100,000 people is equivalent to findings in the Italian population ( 12 ). For the German population it is quite clear from routine DM diagnostics that DM1 and DM2 have the same prevalence, but this varies in other countries.…”

“…There are no well-documented prevalence data for DM2 except of the reports from Finland ( 11 ) and Rome Province in Italy ( 12 ), respectively. We are running one of the main diagnostic labs for neuromuscular diseases performing an estimated proportion of 75% of all tests for DM1/DM2 in Germany.…”

DM1 Phenotype Variability and Triplet Repeat Instability: Challenges in the Development of New Therapies

“…Since then, various laboratories have attempted to correlate, more or less successfully, CTG repeat length, symptoms severity, clinical features, and the classification of clinical forms. The recent developments of registries and cohort studies have made it possible to better characterize the variability of symptoms in populations, and they are valuable tools for correlation studies [5][6][7][8][9][10][11][12][13][14][15]. A recent systematic study performed by the French DM-scope registry has carefully revisited the classification of the disease forms and identified five subtypes in the broad clinical spectrum ( Figure 1 and Table 1) [6,7].…”

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

“…Myotonic dystrophy type 1 or Steinert's disease (DM1, MIM #160900) is the most common form of adult-onset muscular dystrophy, with an estimated prevalence of about 1:8000 among Caucasians; recently, an epidemiological study conducted in the Rome province estimated a total age-standardized prevalence of 9.65/100,000 for DM1 (1).…”