Cappuccino is a defect in a novel protein. (A) A C3H/HeJ-cno/cno mouse (foreground) showing its characteristic severe albinism with a normal littermate (background). (B) Southern blot showing a TaqI polymorphism in cno. gDNA was cut with TaqI, blotted, and probed with a 403-bp fragment (bp 314-716) of BC019169 amplified from normal gDNA with forward primer 5′-AGTTCGTGGGCATGCTGGACATGAT-3′ and reverse primer ACAAGAGTCTCGCTGGAGTCCTCAT-3′. In normal (+/+) DNA, the probe detects a 0.4-kb fragment. In cno/cno DNA, deletion of a TaqI site leaves a larger, 0.8-kb fragment. (C) Direct sequencing reveals an 11-bp deletion (underlined bases) in the cno/cno gene that eliminates a TaqI restriction site (dashed line). (D) Amplification with the above primers and TaqI digestion of gDNA from wild-type littermates (C3H/HeJ-+/+) produces the expected fragments (280 and 120 bp), whereas the cno/cno fragment is not cut. Note the presence of both the wild-type and mutant fragments in heterozygous +/cno DNA. Notably, all other inbred strains tested show the wild-type pattern.