SPINAL muscular atrophy (SMA) is a genetic disorder that affects nerves responsible for muscle function.

It causes the muscles to waste away over time, which can lead to skeletal deformities, such as abnormal curvature of the spine, and problems walking, eating, drinking and even breathing.

It is a rare disorder, affecting around one in 6000 babies born in the UK.

There are three forms of SMA, with the most common, type 1, being the most severe, and usually proving fatal in a child's first year.

Children with milder forms of the disorder can live to adulthood.