World FSHD Day, 20 June

July 18th, 2023

World FSHD Day took place on 20 June. This global initiative aims to raise awareness of Facioscapulohumeral muscular dystrophy (FSHD), one of the most common forms of muscular dystrophy, affecting over one million people worldwide.

What is FSHD?

FSHD is a progressive muscle wasting condition that affects men, women, and children from all walks of life. Despite being considered one of the most common forms of muscular dystrophy in adults and children, there are no treatments and no cure.

FSHD is named for those areas where muscle weakness is usually noticeable: facio (face), scapula (back/shoulder), humeral (upper arm). The condition progresses slowly over time, can lead to weakness in other parts of the body and can impact walking, talking, smiling, and eating.

Causes

FSHD is a complex genetic condition, that involves a complicated interplay between genes and proteins in the muscle cell. While a massive amount of progress has occurred resulting in an improved understanding of the genetic mechanism for FSHD, researchers are still trying to completely understand how the genetic mutation causes the range of symptoms experienced by people with FSHD. There are two known types of FSHD: FSHD1 and FSHD2. However, it is likely that more subtypes of FSHD will be identified as our knowledge of FSHD improves.

FSHD is unlike most genetic conditions where a mutation causes changes in a particular gene and protein. FSHD is caused by mutations that actually increase the expression of a toxic protein.

Nearly all cases of FSHD are associated with a mutation on chromosome 4. Chromosome 4 contains a series of repeated pieces of DNA, called D4Z4 units. People without FSHD1 have 11 to 100 D4Z4 units. In people with FSHD 1 (95 per cent of cases) the D4Z4 array is shortened to 1 to 10 units. With fewer units (repeats), a gene embedded in this region called DUX4 is expressed. The unwanted production of the DUX4 protein sets in motion a cascade of events that leads to loss of muscle function.

Research

Currently, there are no approved drugs for FSHD, and the disease is managed with supportive therapy such as exercise, maintaining bone health, pain management and surgery. Researchers are looking for other ways to help people with FSHD by studying experimental drugs that may improve the functioning of the muscles.

As mentioned in the last newsletter, Fulcrum Therapeutics Inc., a biopharmaceutical company, is investigating the efficacy and safety of Losmapimod for the treatment of FSHD in a phase 3 clinical trial across multiple sites in Europe and USA. If successful, this treatment could have the potential to be the first condition-modifying therapy for FSHD.

Hoffmann-La Roche pharmaceuticals’ clinical trial MANOEUVRE is a Phase 2 study of a medicine called RO7204239 (also called GYM329). Myostatin is a protein that the body produces naturally to control muscle growth. This experimental drug GYM329 has been shown to block myostatin activity. Researchers want to find out if this drug may be an effective way to increase muscle size and strength in people with FSHD. The purpose of this Phase 2 trial is to test if this drug can help muscles grow and, importantly, to assess how safe it is and what the side effects of taking the drug might be.

FSHD Society (USA) have published a pamphlet “You Are Not Alone. A Guide for the Newly Diagnosed”. This resource has quotes from young people, adults, parents, and partners of a person recently diagnosed with FSHD. It describes the range of emotions people may be feeling upon receiving a diagnosis of FSHD.

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