CDKN2A and melanoma: For a second patient diagnosed with melanoma at the age of 54, and belonging to a different melanoma -prone pedigree, a dosage quotient close to 0.5 was obtained for a 9p probe specific of the 5′ end of the transcription unit of the single exon gene KLHL9 (Kelch-like 9, previously named KIAA1354), suggesting a hemizygous deletion in this gene located about 630 kb telomeric from CDKN2A (Figure 3).