Phenotype may predict the clinical course of facioscapolohumeral muscular dystrophy

The correct phenotypic classification of patients with facioscapulohumeral muscular dystrophy (FSHD) is crucial for directing genetic diagnosis and for the definition of outcome measures in clinical trials.

Our objective was to ascertain the utility of the Comprehensive Clinical Evaluation Form (CCEF), the clinical classification proposed by the Italian Clinical Network for FSHD, in an independent FSHD patient population from the UK FSHD Patient Registry. We subdivided the patients into group 1, classic FSHD phenotype/category A of CCEF, and group 2, facial sparing phenotypes/category B1 of CCEF.

Among 642 patients with FSHD1, 68.1% reported facial and shoulder weakness, whereas 24.1% reported shoulder weakness without facial impairment. The phenotype in group 2 was milder, with a higher mean age at onset (P < 0.0001) and less severe motor disability.

Patients with different FSHD phenotypes may have different disease courses. Muscle Nerve 59:711-713, 2019.