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  • Updated 12.28.2020
  • Released 03.09.1995
  • Expires For CME 12.28.2023

Facioscapulohumeral muscular dystrophy

Introduction

Overview

Facioscapulohumeral muscular dystrophy (FSHD) is a dominantly inherited, clinically recognizable, and relatively common muscular dystrophy. It does not generally curtail longevity much, but about 20% of patients use a wheelchair after the age of 50 and are wheelchair dependent. The differential diagnosis is confined to few other conditions, including some limb-girdle dystrophies, a neurogenic form, a scapuloperoneal myopathy, and rare mitochondrial myopathies. The molecular genetic mechanism of facioscapulohumeral muscular dystrophy is unusual, resulting in the expression of a gene, DUX4, which is normally silenced in somatic cells. It has, until recently, remained enigmatic. The authors explain the recent breakthroughs in the understanding of the clinical features and the molecular mechanism underlying facioscapulohumeral muscular dystrophy. To date, there is no effective medical treatment, but the first targeted treatment trial is underway, and many affected people continue to work.

Key points

• Facioscapulohumeral muscular dystrophy (FSHD) can be recognized by inspection and clinical examination; the diagnosis can be confirmed by genetic testing.

• Differential diagnosis is limited to few other conditions. Restrictive lung disease is infrequent but can result in significant morbidity. Regular monitoring of respiratory signs and symptoms is crucial.

• Inheritance is autosomal dominant in most with a high incidence of sporadic cases due to de novo mutations.

• Although genetically distinct, both FSHD1 and FSHD2 result from expression of a normally silenced gene, DUX4.

• Drug treatment is not available, but the first target treatment trial is underway. However, longevity is almost normal.

• Scapular fixation cannot be subject to a blinded, controlled therapeutic trial, but it is gaining in use.

• Published evidence-based care guidelines provide useful information for managing facioscapulohumeral muscular dystrophy and its potential complications.

Historical note and terminology

Landouzy and Dejerine described the disease and gained the eponym (39) even though Duchenne had earlier published a photograph of a patient with typical findings (15). Justin-Bescanon described 3 later generations in the Landouzy-Dejerine family, including the autopsy of 1 of the original patients who died at 86 years of age (33). These original reports remain astute descriptions of the disease, describing the autosomal dominant pattern of inheritance, the protean clinical manifestation, including the mild course of many affected family members, with 1 of their patients having evident facial weakness at 9 years of age but did not have symptomatic limb weakness until 60 years of age.

Comprehensive reviews (80; 93; 97) and a multi-authored monograph (90) summarize all of the clinical aspects of facioscapulohumeral muscular dystrophy in detail. AAN guidelines now provide evidence-based guidelines for the management of FSHD (78). Two expert opinion-based clinical practice recommendations provide guidance for the management of individuals with facioscapulohumeral muscular dystrophy (81; 02). FSHD is the consensus abbreviation.

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