Deletions of 9p21-22, that frequently include theα-,β-andω-IFN gene cluster, are common in malignant diseases such as acute lymphocytic leukemia, malignant melanoma and malignant glioma. There is also evidence to support the role of a gene(s) on chromosome 9p21 in predisposition for familial malignant melanoma.Although initial studies implicated that the IFN genes could serve as tumor suppressor genes, there is now data, mainly based on estimations of minimum region of overlap for the deletions, indicating that the relevant tumor suppressor gene is located centromeric of theα-,β-,ω-IFN gene cluster.