The server from MSKCC predicts the functional impact (high, medium, low, or neutral) of amino-acid substitutions in proteins, such as mutations discovered in cancer or nonsynonymous polymorphisms. The functional impact is assessed based on evolutionary conservation of the affected amino acid in protein homologs. MutationAssessor looks at conservation across all the homologs of a protein and also it takes into account the conservation within just the closest homologs, which is called “specificity.” This gives the tool an advantage in predicting mutations that have a functional impact, particularly those that lead to a change in function rather than a loss or gain of function Registration not required.