Zygosity

Synonyms

Allele similarity

Definition

It describes DNA sequence similarity or origin at a particular genetic locus or between twins. In diploid organisms, where one allele is usually inherited from the mother and one from the father, zygosity describes whether these homologous alleles have identical (homozygous) or different (heterozygous) DNA sequence. A diploid individual may also be missing one (hemizygous) or both (nullizygous) alleles. Alleles are autozygous if they originate from a common ancestor via nonrandom mating or inbreeding; autozygous alleles are homozygous. Alternatively, alleles that coincide via random mating are allozygous and may be homozygous or heterozygous. Twins are described as monozygotic (MZ) when a single egg is fertilized to form one zygote, which later divides into two embryos. Dizygotic(DZ) twins occur when two eggs are fertilized independently, yielding two zygotes; on average, they share 50% of their DNA sequence, similar to nontwin siblings....