The A SNP at this location results in an alternate splice site and the inclusion of a 138 bp cryptic exon (5'). QRT-PCR confirmed reduced transcript levels, likely due to nonsense mediated decay. Western blot analysis confirmed reduced protein levels in heterozygotes. This variant was identified in C57BL/6J and is present in multiple strains (determined by SNP analysis and confirmed by the lack of modifier of Aarssti phenotype activity in MOLF/Ei, DBA/2J, BALB/cJ and C3H/HeJ crosses).