Muscular dystrophies are a group of muscle diseases caused by mutations in different genes which cause loss of function, reduction or absence of protein necessary for muscular stability. The consequences are gradual weakening of muscular tissue and strength deficit that can vary on seriousness, distribution and moment of appearance.

Facio-Scapulo-Humeral Dystrophy (FSHD) is the most frequent genetic muscular disease after Duchenne muscular dystrophy and Steinert myotonic dystrophy: 1 in 8,000 individuals, or 870,000 people worldwide. FSHD strikes men, women, and children of all races and ethnicities. Ten percent develop symptoms before age 10. The condition is inherited and can affect many family members across generations.

Typically beginning in early teenage years with the loss of muscles in the face (facio), shoulders (scapula), upper arms (humerus), legs or core, FSHD can spread to any muscle. The disease has been associated to a particular structure, in the final region of the chromosome 4, established by a reduced number of DNA elements repeated in sequence. Differently from other diseases, an alteration/absence of whichever protein does not correspond to the reduced size of that particular zone of the chromosome 4, since that region does not codify for any protein, generally.