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The knowledge of the effects of single-nucleotide polymorphisms (SNPs) in the human genome greatly contributes to better comprehension of the relation between genetic factors and diseases. Sequence analysis of genomic DNA in different individuals reveals positions where variations that involve individual base substitutions can occur. Single-nucleotide polymorphisms are highly abundant and can have different consequences at phenotypic level. Several attempts were made to apply atomic force microscopy (AFM) to detect and map SNP sites in DNA strands. The most promising approach is the study of DNA mutations producing heteroduplex DNA strands and identifying the mismatches by means of a protein that labels the mismatches. MutS is a protein that is part of a well-known complex of mismatch repair, which initiates the process of repairing when the MutS binds to the mismatched DNA filament. The position of MutS on the DNA filament can be easily recorded by means of AFM imaging.