Type: Inbred Strain TJL Mating System: Sib … Type: Inbred Strain TJL Mating System: Sibling x Sibling (Female x Male) Species: laboratory mouse H2 Haplotype: a Generation: F275 (14-DEC-06) Appearance albino Related Genotype: a/a Tyrp1b/Tyrp1b Tyrc/Tyrc Important Note This strain is homozygous for Cdh23ahl, the age related hearing loss 1 mutation, which on this background results in progressive hearing loss with onset between 3 and 5 months of age. Strain Description Developed by LC Strong in 1921 from a cross between a Cold Spring Harbor albino and a Bagg albino, the A inbred strain is used widely used in cancer and immunology research. It is highly susceptible to cortisone-induced congenital cleft palate by cortisone. It has a high incidence of spontaneous lung adenomas, and lung tumors readily develop in response to carcinogens. A high percentage of mammary adenocarcinomas (a large proportion acinar type) develop in multiparous females. Rare spontaneous myoepitheliomas arising from myoepithelial cells of various exocrine glands have been observed in The Jackson Laboratory substrains. A/J mice, fed an atherogenic diet (1.25% cholesterol, 0.5% cholic acid, and 15% fat), fail to develop atherosclerotic aortic lesions in contrast to several highly susceptible strains of mice (e.g. C57BL/6J, Stock No. 000664; C57L/J, Stock No. 000668, C57BR/cdJ, Stock No. 000667, and SM/J, Stock No. 000687). A/J mice develop cigarette smoke-induced emphysema in approximately half the time when compared with C57BL/6J mice. This inbred strain develops a late onset (4-5 months) progressive muscular dystrophy as a result of a retrotransposon insertion in the dysferlin (Dysf) gene. The Dysfprmd allele, carried by A/J mice, has been shown to result in degeneration and regeneration of myofibers and centrally placed nuclei. Proximal muscles are more severely affected than distal muscles (Ho M, et al. 2004). Sequencing of the mitochondrial genome of A/J revealed 10 adenines in a polymorphic adenine repeat sequence in the mt-Tr sequence. This repeat contains 9 adenines in NOD/LtJ, A/HeJ, A/WySnJ, and SKH2/J and 10 adenines in A/J, and NZB/B1NJ, and likely enhances the hearing loss associated w ith the ahl allele of Cdh23 (Johnson et al., 2001). hl allele of Cdh23 (Johnson et al., 2001).