Clinical features of facioscapulohumeral muscular dystrophy 1 in childhood

To explore the clinical course of patients presenting with facioscapulohumeral dystrophy type 1 (FSHD1) in childhood, with a view to identifying areas where they differed from older patients and where extra support or monitoring might be required.

A retrospective case-notes review of children with FSHD1 seen at a tertiary paediatric neuromuscular centre between 2002 and 2016 was performed. Data collected included age at and nature of presentation, path to diagnosis, genetic testing results, motor function, and occurrence of extramuscular features and complications.

Eighteen children (11 females, seven males; mean [SD] age at latest review 13y 10mo [3y 9mo], range 8-19y) from 16 families were identified. Age at onset of FSHD1 correlated with the size of deletion (r=0.81) and most presentations were in children either younger than 5 years or older than 10 years. Children with onset before 5 years were more likely to present with non-muscular symptoms and to develop extramuscular pathology, including developmental and psychiatric issues, hearing or visual impairments, and problems involving respiratory function and nutrition. No cases of epilepsy or cardiac arrhythmia were identified but two children died.

The complexity and severity of FSHD1 presenting in early childhood underlines the importance of a multidisciplinary approach to the disorder.

Young children often present with non-muscular pathology in facioscapulohumeral dystrophy type 1 (FSHD1), especially hearing loss. Age at onset in paediatric FSHD1 appears bimodal: under 5 years or in adolescence. Prolonged delays to diagnosis are common. Children with very early-onset FSHD1 may require nutritional and/or respiratory support. Developmental and psychiatric comorbidities are common.