Laura Stobie, 21, is learning to live with a rare medical condition that is proving to be a genetic riddle doctors are so far unable to solve.

Hereditary Spastic Paraparesis (HSP) causes Laura's legs to stiffen, but medical specialists can't say what causes it, or if there will ever be a treatment or cure.

Reporting by LAURA McFADZEAN

Filming by LAURA McFADZEAN