The mutant mouse line yeti was isolated in a recessive ENU mutagenesis screen for genes affecting embryonic development. The locus was mapped to a 3.5 Mb interval between rs6278243 and rs29154438 on chromosome 12. A single G>A mutation was identified in the splice acceptor site of exon 22. RT-PCR analysis of cDNA confirmed aberrant splicing of the Wdr35 mRNA in heterozygous and homozygous embryos. Sequencing of these mutant splice variants revealed frameshifts in all transcripts. Noncomplementation of this allele with an embryonic stem cell derived targeted null allele proves that the mutant phenotype is due to this point mutation.