[Zallen JA] ky123 recessive, homozygotes exhibit aberrant anterior position of nerve ring, many ring axons misrouted, ventral nerve cord neurons often misrouted, cross midline. Encodes three isoforms, longest 1273 aa with 5 Ig repeats, 3 FNIII repeats, TM domain, large cytoplasmic domain. ky123 deletes signal sequence and first exon, probable null. Predicted gene ZK377.3 + ZK377.2