When he was 18 he was diagnosed with a neurological disease called hereditary spastic paraparesis, or HSP.
From the kansas.com
Exome sequencing and disease-network analysis of a single family implicate a mutation in KIF1A in hereditary spastic paraparesis.
From the sciencedaily.com
Little did not have any spasticity himself, but he suffered childhood poliomyelitis with residual left lower-extremity paraparesis, complicated by severe talipes.