The promoter mutation so far only seen in human and cat, which render them free of lactose intolerance. However, the frequency of such mutation is much higher in Euripean desendent, not very high in Asian (both human can cats).

http://www.ncbi.nlm.nih.gov/entrez/dispomim.cgi?id=223100

I do not know how true the story about cat is. Your cat may just have the mutation.