Treacher-Collins syndrome and co-existing dermatomyositis

Background: Treacher-Collins syndrome, an autosomal dominantly inherited malformation of structures derived from the first and second branchial arch, has an incidence of 1:10,000 newborns. The prevalence of dermatomyositis at less than 24 years of age has been estimated at 1 per 100,000. The occurrence of both Treacher-Collins syndrome and dermatomyositis combined in the same patient should occur once in every 1,000,000,000 subjects. Methods: We report a patient with Treacher-Collins syndrome who developed dermatomyositis at the age of 5 years. Results: No other patient with both Treacher-Collins syndrome and an autoimmune disease has been reported. The thymus originates from the third branchial pouch and is unaffected by the syndrome. In Treacher-Collins syndrome the affected gene has been mapped to the fifth chromosome, while dermatomyositis is related to HLA B8 and DR3, coded on the sixth chromosome. No immunologic alteration has been described in patients with Treacher-Collins syndrome. Conclusion: This is the first report of a patient with Treacher-Collins syndrome and dermatomyositis. There is no genetic or physiopathologic explanation for the concurrence of both conditions.