HPDL and nervous system disorder: In summary, we propose that the evidence for an autosomal recessive spastic cerebral palsy-1 (CPSQ1; OMIM 603513) locus at 2q31.1 resulting from a mutation in the GAD1 gene is insecure and that the single family reported to have a GAD1-related neurological disorder are most likely to have a HPDL-related autosomal recessive disorder.