ADHD patients with the 4.7 allele also tend to have better cognitive performance and long term outcomes compared to ADHD patients without the 4.7 allele, suggesting that the allele is associated with a more benign form of ADHD.

The D4.7 allele has suppressed gene expression compared to other variants.

Only those cells losing this remaining functional allele of the BRCA1 or BRCA2 gene will become tumors.

30 to 50 of people of Chinese and Japanese ancestry have at least one ALDH 2 allele.

The TCF7L2 allele, for example, increases the risk of developing diabetes by 1.5 times and is the greatest risk of the common genetic variants.

When there are few copies of an allele, the effect of genetic drift is larger, and when there are many copies the effect is smaller.

The blue Doberman has the color gene with at least one dominant allele and the dilution gene with both recessive alleles (i.e., BBdd or Bbdd).

The normal cells of women carrying the BRCA1 or BRCA2 mutations can still recombine, because they retain one functional allele or alternative form of the gene.

The reason is simple cells that have recently lost the functional BRCA1 or BRCA2 allele and that will later grow into tumors will also be unable to undergo recombination.

According to the analysis by HapMap Project, the rs671 allele of the ALDH2 gene responsible for the flush reaction is rare among Europeans and Africans, and it is very rare among Mexican Americans.

At that time when dietary iron may have been scarcer than today, the presence of the mutant allele may have provided an evolutionary or natural selection reproductive advantage by maintaining higher iron levels in the blood.

In population genetics, fixation is the change in a gene pool from a situation where there exists at least two variants of a particular gene (allele) to a situation where only one of the alleles remains.