Dr. Palmer gives talk for Rat Genome meeting

Dr. Palmer gave an online presentation titled "The surprise appearance of an XY female, characterizing a spontaneous mutation in the HS rat colony" during the monthly Rat Genome meeting in April 2026 organized by Dr. Hao Chen (on behalf of the International Rat Omics Consortium (IROC).

Here is a bit of background about our HS West rat colony and the rat Y Chromosome:

Palmer Lab maintains a large outbred rat colony that was derived from 8 inbred strains about 110 generations ago.

Currently we have ~70 breeding pairs and we produce ~500 pups every 3 months. We use ~0.25x whole genome sequencing to impute millions of SNP genotypes. As a QC step, we examine the proportion of reads mapping to the X and Y Chromosomes.

We recently noticed some anomalous results: fertile XY females, and XXY and XYY individuals that were part of a multigenerational pedigree.

We strongly suspect this is due to a spontaneous mutation on the Y chromosome (we’re calling it Y') that somehow lacks SRY activity.  We're still trying to identify the causal mutation. We have T2T assemblies of the 8 founders and have generated a lot of sequence on Y’, including both deep short and ONT ultra-long reads.