Endocrine Abstracts

Background: The myotonic dystrophy type 1 (DM1) or Steinert disease is the most common inherited, autosomal dominant neuromuscular disorder in adult. The gonadal dysfunction has been known for many years in DM1 men with description of bilateral testicular atrophy but the factors influencing the different profiles of gonadal dysfunction, and their natural evolution are not clearly established. The purpose of this study was to determine the profiles of gonadal function on men affected by DM1 followed in a single reference center and to analyse the factors influencing this gonadal profile.

Results: in the whole population, the mean age of the 75 patients was around 40 years, 57% of them being younger than 40 years old. More than half (53.3%) of these 75 patients had an adult form of the disease. The median number of CTG repeat was 450 (200–650). Forty percent of the patients had normal gonadal status. Sixty percent of patients had alteration of hormonal results. Thirty-seven percent of patients had isolated exocrine testicular lesion and 22% of patients had hypogonadism. This last, hypogonadal patients, had higher BMI and had more metabolic disorders than in patients with exocrine testicular failure or normal gonadal status. They had also more severe disease (evaluated by the number of triplets) and more severe muscular involvement (evaluated by MIRS score) than other patients, regardless of their age. Also paternity was significantly lower in hypogonadic patients than in other patients. Testosterone (t) and testosterone/SBP ratio (t/S) were inversely correlated with the age of patients (t: r = −0.32, P = 0.005; t/S: r = −0.49, P < 0.001) and with the MIRS score (t: r = −0.37, P = 0.001; t/S: r = −0.32, P = 0.006). There was not correlated with paternity and number of CTG repeats.

Conclusion: In this cohort of 75 DM1 patients aged arount 40, we observed a high prevalence of primary testicular failure with one patient out of 5 with hypogonadism. This gonadal dysfunction was significantly correlated to the number of CTG repeats, the severity of muscle involvement assessed with the MIRS score, and the metabolic syndrome regardless of the age of the patients.

The efficacy of androgen therapy on metabolic and muscular syndrome, and its acceptability by patients need to be studied, as well as the effect of an improvement of metabolic status or muscular strength through rehabilitation that might also have beneficial effects.