Genetical control of the anaphylactoid reaction in rats

A recessive autosomal gene, dx , preventing the anaphylactoid reaction has been discovered in a stock of Wistar albino rats from the Agricultural Research Council, Compton. 2. Segregation occurred in the F2 generation derived from crossing pure-bred reactor rats and pure-bred non-reactor rats. 3. Non-reactivity was outbred into non-albino stocks and was shown to segregate independently of the albino gene c and not to be closely linked to the colour genes, P and A . 4. The mutation from Dx to dx may have arisen a few years ago in one of the Wistar colonies before it was split into sub-lines. 5. The dx gene is fixed in several brother-sister mated sub-lines and appears to be in equilibrium with Dx in some less inbred closed-populations.