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's 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.