Facioscapulohumeral muscular dystrophy

Rabi Tawil MD (Dr. Tawil of the University of Rochester School of Medicine and Dentistry received consultation fees from aTyr, Cytokinetics, and Novartis.)
Salvatore DiMauro MD, editor. (Dr. DiMauro, Director Emeritus of H Houston Merritt Clinical Center for the Study of Muscular Dystrophy and Related Diseases at Columbia University, has no relevant financial relationships to disclose.)
Originally released March 9, 1995; last updated January 24, 2017; expires January 24, 2020

This article includes discussion of facioscapulohumeral muscular dystrophy, Landouzy-Dejerine muscular dystrophy, facioscapulohumeral disease, facioscapulohumeral dystrophy, facioscapulohumeral syndrome, FSHD, and FSHMD. The foregoing terms may include synonyms, similar disorders, variations in usage, and abbreviations.

Overview

Facioscapulohumeral muscular dystrophy (FSHD) is a dominantly inherited, clinically recognizable, and relatively common muscular dystrophy. It does not curtail longevity much, but about 20% of patients use a wheelchair after the age of 50. 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 FSHD has, until recently, remained enigmatic. The author explains the recent breakthroughs in our understanding of the molecular mechanism underlying FSHD. To date, medical treatment is not effective, but 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.

 

• 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 longevity is almost normal.

 

• Scapular fixation cannot be subject to a blinded, controlled therapeutic trial, but it is gaining in use. Recently published evidence-based care guidelines provide useful information for managing FSHD and its potential complications

Historical note and terminology

Landouzy and Dejerine described the disease and gained the eponym (Landouzy and Dejerine 1885) even though Duchenne had earlier published a photograph of a patient with typical findings (Duchenne 1862). Justin-Bescanon described 3 later generations in the Landouzy-Dejerine family, including the autopsy of one of the original patients who died at 86 years of age (Justin-Bescanon et al 1964). From the beginning, there have been debates about the neurogenic or myopathic origin of the weakness and wasting. However, the autosomal dominant pattern of inheritance was evident in the original family described by Landouzy and Dejerine, and little has been added to the clinical manifestations, including the mild course of many affected family members. One of their patients had evident facial weakness at 9 years of age but did not have symptomatic limb weakness until 60 years of age.

After World War II, a genetic study was carried out with the aid of Mormon Church records in Salt Lake City, Utah, reaffirming the clinical picture and autosomal dominant inheritance (Tyler and Stephens 1950). In that study, many affected family members showed signs of the disease but had no symptoms. A few years later, Walton and Nattrass included the facioscapulohumeral form as 1 of the 3 major categories of muscular dystrophy (Walton and Nattrass 1954). (The other 2 were X-linked Duchenne dystrophy and limb-girdle muscular dystrophy.) In 2004, Mostacciuolo and colleagues found 40 probands in the province of Padova, population 871,190, for a prevalence of 1:22,000 (Mostacciuolo et al 2009). Upadhyaya and colleagues mapped the gene to 4q35, ending debates about the clinical diagnosis of similar syndromes (Upadhyaya et al 1990). As discussed below, the clinical diagnosis must be confirmed by documenting the mutation in at least 1 family member.

Comprehensive reviews (Tawil and van der Maarel 2006; van der Maarel et al 2007) and a multi-authored monograph (Upadhyaya and Cooper 2004) summarize all of the clinical aspects of facioscapulohumeral muscular dystrophy in detail. AAN guidelines now provide evidence-based guidelines for the management of FSHD, superseding 2 previous consensus-based guidelines. Two expert opinion-based clinical practice recommendations provide guidance for the management of individuals with facioscapulohumeral muscular dystrophy (Tawil et al 2010; Attarian et al 2012). FSHD is the consensus abbreviation.

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