Itpr3 Is Responsible for the Mouse Tufted (tf)  Locus

The tf (tufted) locus is responsible for a classic phenotype of hair loss and regrowth in mice. It is a characteristic of the BTBR strain. Here, we use a combination of positional cloning methods and complementation mapping to identify Itpr3, the inositol triphosphate receptor type 3, as the gene responsible for the tf locus. Key words: BTBR mouse, hair, inosine triphosphate receptor type 3 When a tufted mouse is 4 weeks old, lines of hair loss begin to spread in waves from its snout to its tail. The first wave takes about a week, the second about 18 days, and subse-quent waves take a month or longer (Figure 1). The tufted (tf) locus was recognized as a spontaneous mutation in the year 1956 (Lyon, 1956) and early work located it near the kinky/fused (Fu) and brachyury (T) loci (Dobrovolskaia