While it is well known that the genome of one individual can have extensive differences when compared to the genome of another, recent research has found that some coding regions are highly [[Conservedconstrained, sequence|conserved]]or resistant to mutation, between individuals of the same species. ResearchershaveThis is similar to the concept of interspecies constraint in [[Conserved sequence|conserved sequences]]. Researchers termed these highly constrained sequences constrained coding regions (CCRs), and have also discovered that such regions may be involved in [[high purifying selection]]. On average, orthere theis removalapproximately of1 [[Deleteriousprotein-altering mutation|deleterious]]mutationsevery 7 coding bases, resultingbut insome notCCRs evencan ahave singleover occurrence100 of mutationbases in regionssequence rangingwith fromno 7observation codingprotein-altering basesmutations, tosome sometimeswithout even 100synonymous sequential basesmutations.<ref name=":0">Havrilla, J. M., Pedersen, B. S., Layer, R. M., & Quinlan, A. R. (2018). A map of constrained coding regions in the human genome. ''Nature Genetics'', 88–95. doi: 10.1101/220814</ref> These patterns of constraint between genomes may provide clues to the sources of rare [[Developmental disorder|developmental diseases]] or potentially even embryonic lethality. sinceClinically validated variants and [[de novo mutation]]s in CCRs have been previously linked to disorders such as [[infantile epileptic encephalopathy]], developmental delay and severe heart disease.<ref name=":0" />
