“Myotonic Dystrophy type1 (DM1) is a multisystemic disorder due to a CTG expansion resulting in a toxic mRNA causing mis-splicing of several proteins responsible for different clinical manifestations. Cutaneous manifestations of DM1 include frontal alopecia, pilomatricomas, and other benign and malignant skin neoplasms. Nevertheless, the association of psoriasis and DM1 has never been reported.

We investigated the occurrence and characteristics of cutaneous psoriasis in a cohort of 65 DM1 patients. Demographic and genetic DM1 data were collected for all patients. Age at onset, disease duration and treatment strategies were investigated for all patients with psoriasis.

Fifteen patients were affected by psoriasis resulting in a prevalence of 23% in our cohort. Seventy-five% of patients were males and mean age was 50 years. DM1 inheritance was paternal in 78%, maternal in 7% and unknown in 15%. Fifty% of patients had a family history of psoriasis, half showing a concordant DM1 inheritance. Seventy-nine% of patients had E2 expansion class whereas 21% E1. Median age at onset of psoriasis was 33 years while 26 for DM1. Seventy-seven% of patients required treatment for disease control, 90% of which was topical and 10% systemic.

The overall prevalence of psoriasis in DM1 seems to be 10 times higher than in the general population (worldwide prevalence: 2-3%) and 5 times higher than in Lazio region of Italy (4-5%). Psoriasis could be an additional cutaneous manifestation of DM1. Further investigations are needed to assess whether mis-splicing of specific genes could underlie the increased risk of psoriasis in DM1 population.”