The Smn (survival motor neuron) genes (Smn1 in mouse; SMN1 and the nearly identical SMN2 in humans) are found in a 500 kb inverted duplication on human chromosome 5q13. Loss of Smn1 due to exon 7 skipping is associated with spinal muscular atrophy (SMA). Mice carrying allele C (Smn1tm5(Smn1/SMN2)Mrph) develop a mild form of SMA that does not effect lifespan. Tia1 (cytotoxic granule-associated RNA binding protein 1) encodes a member of the RNA binding family that regulates SMN exon 7 splicing. In C+/+/Tia1-/- mice, the knock-in allele, allele C, a hybrid allele consisting of two tandem mouse Smn1/human SMN2 genes, is combined with the Tia1 knock-out allele, double homozygous females develop earlier tail loss with the addition of the Tia1 allele, but develop tail necrosis similar to the C+/+ mice. Reproductive organ development is impaired in double homozygote males. Specifically, testes mass is reduced, degeneration of seimiferous tubules is increased, sperm count is reduced, and spermatogenesis is impaired as compared to C+/+ males Mice homozygous for the Tia1 allele and heterozygous for the Smn1 allele (C+/Tia-/-) are viable and fertile. This mutant mouse strain may be useful in studies of modifiers of a mild mouse model of SMA.

C+/+/Tia1-/- mice carry the knock-in allele, Smn1 (also known as allele C), a hybrid allele consisting of two tandem mouse Smn1/human SMN2 genes and the Tia1 knock-out allele. Female mice develop tail shortening and necrosis. Males exhibit impaired reproductive organ development. This mutant mouse strain may be useful in studies of modifiers of a mild mouse model of SMA.

This strain is hosted by NIH's MMRRC, which partners with JAX for the distribution of this and other strains. For additional information and to purchase, please visit the MMRRC site.