Investigators at University of Rochester Medical Center, NY; Hopital Archet-CHU de Nice, France; and Albert Einstein College of Medicine, NY, studied the frequency of Coats syndrome and its association with D4Z4 contraction size in 408 patients identified with facioscapulohumeral dystrophy type 1 (FSHD1). Three patients (0.8%) had a history of Coats disease, and 14 patients had FSHD and Coats syndrome confirmed by ophthalmologic examination. Median age at diagnosis of Coats syndrome was 10 years. The median D4Z4 fragment size was 13 kilobases. Close surveillance for retinal complications is recommended in FSHD1 patients with D4Z4 fragments <15kb. [1]

COMMENT. Coats disease, characterized by exudative retinitis and telangiectases of the retina, with slow progression to retinal detachment, may occur alone as an idiopathic form, unilateral, in males with onset at age 1-20 years, or as a syndrome, associated with FSHD1 and high-frequency hearing loss. FSHD1 is caused by a loss of D4Z4 repeat units on chromosome 4q35. Coats disease in the FSHD-associated syndrome is bilateral, it occurs at any age, and most frequently in female patients with FSHD and large contractions (allele size <15 kb). Contraction size (<15 kb) rather than age or FSHD severity should determine the need for annual retinal examinations for retinal vascularinvolvement and possible surgery. An early sign of Coats disease is a yellow-eye in flash photography, a reflection off cholesterol deposits in retinal blood vessels.

Coats disease is named after George Coats [2]. A syndrome characterized by retinal, hearing, muscle and mental disorders was described 60 years later by Robert G. Small. [3]