The DNA mutation causing FSHD can be recognised from a blood sample in most cases.
The sample will need to be forwarded to one of a few molecular genetic laboratories able to analyse it for this mutation.
Unlike most inherited muscle-wasting conditions, which are usually caused by a mutation of an important muscle gene, the genetics of FSHD is very complex. FSHD is caused by the production of a protein called DUX4 – which is not normally made in muscle.
There are two types of FSHD (FSHD 1 & 2). Both forms are caused by production of DUX4, but the underlying mechanisms that lead to its activity are different. DUX4 is a so-called transcription factor that switches on genes that are normally not active in the muscle cell. This is toxic for the cell and can lead to its death – resulting in muscle wasting and weakness.