Harley's have a few main issues that are known to their lines, including aggression, lactation issues and skin issues.
My Harley rats have been adopted from GBR and she has informed me that there are no aggression or lactation issues in her line, but the Harley's do have skin flareups after their first moult and during pregnancy.
Due to this, when you bring your Harley baby home, you may notice that their skin is delicate and prone to scratching and scabbing. The best way known to help out with this is to coat their skin with coconut oil, and to add fish oil supplements to their diet. Much like a naked rat, this will help their skin stay moisturized and strong when they are young.
This issue, according to GBR, should fade a few weeks after the first moult and is nothing to worry about. Just be aware that your harley baby may require some extra care post moult!