Final answer:
Few mutations have been isolated in histones because they are highly conserved proteins critical to DNA structure and function, some mutations in histones can be lethal to the cell, and cells can rapidly repair such changes to maintain genomic stability.
Step-by-step explanation:
The reason why few mutations have been isolated in histones compared to other genes can be attributed to a combination of factors. Firstly, histones are highly conserved proteins which means that they have remained almost unchanged throughout evolution due to their critical role in DNA packaging and regulation. This implies that mutations in histones can be incredibly detrimental to cell function. Secondly, some mutations in histones can be lethal to the cell (Mutations in histones are lethal to the cell), as histones play a crucial role in the structure and function of chromosomes. Lastly, cells possess multiple repair mechanisms to fix mutations in DNA to maintain genomic stability. Therefore, if histones do get mutated, the cell is likely to repair these changes rapidly to prevent adverse effects. It's worth noting that histones are indeed involved in gene regulation through epigenetic mechanisms like acetylation and methylation, which affect chromatin structure and gene expression without altering the DNA sequence itself.