Human Biological Variation

locus

any position in the genome including one or more

nucleotides that can harbor one or more alleles.

Sometime used only to refer to protein coding genes

allele

a specific variant in a locus (e.g. A versus a). May

represent a SNP, a structural variant, or something else

mutation

a change in allelic state (typically during

production of germ cells)

mutation rate

the rate of introduction of new alleles per

time unit (year, generations) per genetic unit (nucleotide,

genome, gene)

haploid

one copy of the DNA

diploid

two copies of the DNA

polymorphism

locus that is genetically variable in the

population

genotype

the combination of alleles in an individual in a

locus (e.g., Aa)

homozygous

AA or aa

heterozygous

Aa

SNP

single nucleotide polymorphism,

i.e. mutation affecting a single site. Synonymous with a

'segregating site'

site

a particular single nucleotide position in the genome

haplotype

a specific (haploid) DNA sequence found in

one or more individuals, e.g. 'AGGTCGAATA'

recombination

exchange of DNA between

maternally and paternally inherited copies of DNA

during meiosis

mtDNA

the DNA located in the mitochondria (which

doesn't recombine and is effectively haploid)