This phenotypic mutant was identified in an ENU mutagenesis screen. The molecular lesion is a T to C substitution in exon 5 of the gene (position 11:80,817,609 (GRCm38/mm10) Assembly). This mutation leads to the substitution of the nonpolar aliphatic amino acid, isoleucine, by the polar amino acid threonine (p.I135T) in the encoded protein. (J:277123)