Facio-scapulo-humeral myopathy (FSH) is a genetic disorder that affects about 3,000 persons in France, it is one of the most common muscular dystrophies in adults. There are two types (FSHD1 in 95% of cases, and FSHD2) genetically distinct but both due to the aberrant expression of the DUX4 gene, toxic to skeletal muscle. Selective muscle damage (face, shoulders, etc.) can be associated with retinal vasculopathy that slowly progresses and is generally asymptomatic.
From eye to gene
A team from the Netherlands carried out a study of retinal involvement in 33 patients registered with the National Reference Center for FSH and 24 control subjects. All underwent a clinical examination (ophthalmologic and neurologic), genetic tests, fundus photographs, structural optical coherence tomography (OCT-SD), and angiographic OCT (OCT-A ) which allows the retinal blood vessels to be studied quickly and non-invasively. The Dutch researchers conclude that:
- retinal abnormalities are frequent in patients with FSH in this cohort, but most often subclinical;
- they consist mainly of foveal anomalies (7/33) and tortuosity of the retinal arterioles (25 out of 33 cases, i.e. nearly 76%), detected by non-invasive imaging (OCT-A);
- vascular tortuosity is inversely correlated with the size of the D4Z4 repeats on chromosome 4; however, there is no correlation with muscle weakness;
- retinal involvement remained stable in a subgroup of 6 patients, followed for 2 years, where other studies had shown the possibility of progression.
These findings provide, non-invasively, clinical evidence of an underlying genetic link between the retina and facioscapulohumeral dystrophy.
