None of the five neurofibromas had any CNA, but two samples (Cases 99 and 166) from patients with neurofibromatosis type 1 showed LOH at the NF1 locus, possibly representing the somatic event in the functional inactivation of NF1. Two of the patients underwent surgical treatment, and renewed SNP array analysis was performed on one of them (Case 99), now also showing a deletion of CDKN2A in 9p and a deletion in Xq. The gene discussed is CDKN2A; the disease is neurofibromatosis type 1.