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Cataracts have been associated with many mutations. In a large-scale high-throughput ENU mutagenesis screen we analyzed the offspring of paternally treated C3HeB/FeJ mice for obvious ocular dysmorphologies. We identified a mutant suffering from rough coat and small eyes only in homozygotes; homozygous females turned out to be sterile. The mutation was mapped to chromosome 7 between the markers 116J6.1 and D7Mit294. The critical interval (8.6 Mb) contains 3 candidate genes ( Apoe, Six5, Opa3); none of them showed a mutation. Using exome sequencing, we identified a c.2209T>C mutation in the Xpd/ Ercc2 gene leading to a Ser737Pro exchange. During embryonic development, the mutant eyes did not show major changes. Postnatal histological analyses demonstrated small cortical vacuoles; later, cortical cataracts developed. Since XPD/ ERCC2 is involved in DNA repair, we checked also for the presence of the repair-associated histone γH2 AX in the lens. During the time, when primary lens fiber cell nuclei are degraded, γH2 AX was strongly expressed in the cell nuclei; later, it demarcates clearly the border of the lens cortex to the organelle-free zone. These findings demonstrate the importance of XPD/ ERCC2 for lens fiber cell differentiation. [ABSTRACT FROM AUTHOR]

Purpose The mouse mutant KTA48 was identified within the recessive Munich ENU Project among offspring of treated C3HeB/FeJ mice. It is characterized by a kinky tail, white belly spot and small dull eyes. Methods Linkage analysis was performed using SNP‐based technology and microsatellite markers. Sequence analysis, histology and in‐situ hybridization were performed according to standard techniques. Results The genome‐wide linkage analysis mapped the KTA48 mutation on chromosome 12; positional candidate gene analysis detected a mutation in the Pxdn gene (encoding peroxidasin) co‐segregating with the mutation. The Pxdn‐mRNA of the KTA48 mutants contains a T‐>A mutation at pos. 3816 (T3816A) creating a new Alw26I restriction site; the mutation converts the Cys at codon 1272 into a stop codon (Cys1272X). The mutation co‐segregates with the phenotype in the breeding colony; it is not present in several wild‐type strains. The lens phenotype is slightly variable. During an early stage of eye development (E12.5), Pxdn is expressed in the posterior part of the lens and in the central part of the retina without obvious changes. At the end of embryonic development (E17.5), we observed small lenses outside the optical axis and rupture of the lens capsule. Later, microphagia is accompanied by deformed cornea and multilayered retina. At P21, the small lens is attached to the cornea, and in some cases, the eye is completely disorganized.. Conclusion The recessive mouse mutation KTA48 is caused by a premature stop codon of the Pxdn gene. The function of Peroxidasin is still unknown; there is no mutation known neither in humans nor in mice. [ABSTRACT FROM AUTHOR]