By contrast,homozygousis when there are two copies of the same allele at the same locus.
The specific pairing of alleles translates to variations in an individuals genetic traits.
An allele can either be dominant or recessive.
Dominant alleles are those that express a trait even if there is only one copy.
Recessive alleles can only express themselves if there are two copies.
This might create a skin tone somewhere in between.
Other factors, such as lifestyle and environment, would also play a part.
Much research is focused on “parent of origin” genetic contributions.
If the mutated allele is recessive, the person will usually not be affected.
Single gene disorders are relatively rare.
The risk will be the same for every birth.
These are typically rare disorders that are often linked to race or ethnicity.
Some combinations translate to childhood disease, while others translate to later onset disease.
This causes seizures, brain disorders, and intellectual disability.
This is a phenomenon referred to as heterozygote advantage.
Among the examples:
Sickle cell anemia
Sickle cell anemia is a genetic disorder due to two recessive alleles.
Having both alleles causes the malformation and rapid self-destruction of red blood cells.
By increasing mucus production, a person is less susceptible to the damaging effect of infectious diarrhea.
Newman DL, Coakley A, Link A, Mills K, Wright LK.Punnett squares or protein production?
The expert-novice divide for conceptions of genes and gene expression.CBE Life Sci Educ.
2021;20(4):ar53.
NIH Genetics Home Reference.Neurofibromatosis bang out 1.
NIH Genetics Home Reference.Tay-Sachs Disease.
NIH Genetics Home Reference.Phenylketonuria.
Centers for Disease Control and Prevention.Protective Effect of Sickle Cell Trait Against Malaria.
NIH Genetics Reference Home.Cystic Fibrosis.
