Linkage analysis of the tuft mutation

Abstract

A spontaneous mouse mutant, tuft, exhibits a large intracranial lipoma, the development of which is consistent with a neural tube defect. The purpose of this study was to identify the tuft locus, appraise possible candidate genes, and evaluate two different methods of DNA electrophoresis, one of which was used in previous work. Linkage analysis mapped the tuft mutation to two candidate regions on chromosome 10 within 16Mb distal and proximal to D10MIT115, at 60Mb and 80Mb respectively. Primers designed by the author for microsatellites in these regions were non informative. A literature survey showed the tuft mutation shares a similar phenotype with only one known mutation on chromosome 10 affecting the Apafl gene. A primer designed by the author, WD5, for a micro satellite 2kb from the Apafl gene showed a recombination percentage of 35%. A microsatellite marker within 1cM of the gene containing the tuft mutation would be expected to show a near zero recombination percentage. PCR products for two primers designed by the author for microsatellites on chromosome 10 were analyzed using the 4% metaphor gel method, which was previously used, and a Beckman/Coulter CEQ 8000 capillary based method. All samples which showed a result in both methods showed the same result, with a single exception which is likely due to the greater sensitivity of the CEQ. These data suggest that tuft maps to chromosome 10 within 16Mb of the microsatellite marker D10MIT115, that the tuft mutation is not likely located within the Apafl gene, and that the genotypic methods used are reliable.