Which type of mutation would not contribute to the inactivation of a tumor suppressor gene?

The type of mutation that would not contribute to the inactivation of a tumor suppressor gene is a duplication of the gene. When a tumor suppressor gene is duplicated, it results in an increased amount of the gene product, which can lead to enhanced function rather than inactivation. Tumor suppressor genes typically function to regulate cell growth and division, and having more of the gene product can potentially enhance its role in suppressing tumors. This contrasts with the other types of mutations, such as silencing by epigenetic changes, loss-of-function mutations, or chromosomal deletions, which all lead to a reduction or complete loss of the gene's normal function, contributing to tumorigenesis.