Polymorphism or variant

any heritable DNA sequence variation

Single nucleotide polymorphism (SNP)

the simplest type of DNA variant

Non-synonymous SNP

a SNP that changes the coding region of a gene  resulting in an amino acid substitution

Synonymous SNP

a SNP within a protein-coding region that does not  result in an amino acid substitution

Mutation

any heritable DNA sequence variation that  causes disease or disease susceptibility

Benign variant

a DNA sequence variation that does not  cause disease or disease susceptibility

Common variant

a polymorphism found in > 1% of a population

Alleles

alternative forms of a DNA sequence

Penetrance

the proportion of individuals carrying a genetic variation  who exhibit an associated trait or disease