- delays in reaching development milestones – for example, not sitting by eight months or not walking by 18 months
- seeming too stiff or too floppy
- weak arms or legs
- fidgety, jerky or clumsy movements
- random, uncontrolled movements
- walking on tip-toes
- a range of other problems – such as swallowing difficulties, speaking problems, vision problems and learning disabilities
The severity of symptoms can vary significantly. Some people only have minor problems, while others may be severely disabled.