t-Haplotypes of the mouse may involve a change in intercalary DNA.

The naturally occurring t-haplotypes of the mouse exhibit a set of peculiar genetic properties, including strong suppression of crossing over in the segment of chromosome 17 between the loci of T and H--2. Study of the genetics of mutant haplotypes suggests that the observed effects on meiosis and embryonic development may be due to an altered form of intercalary DNA (iDNA) in the relevant chromosomal region (band 17B).