ITPR1 and ataxic cerebral palsy: In the study presented here, four children were identified who had a working diagnosis of sporadic ataxic cerebral palsy and were found to have de novo mutations in three different genes: KCNC3, which encodes a voltage-gated potassium channel (Kv3.3); ITPR1, which encodes the receptor for inositol 1,4,5-trisphosphate (IP3R); and SPTBN2, which encodes β-III spectrin.