Allelic heterogeneity
Encyclopedia
Allelic heterogeneity is the phenomenon in which different mutations at the same locus
(or gene
) cause the same disorder
. For example, β-thalassemia
may be caused by several different mutations in the β-globin gene. It is a type of genetic heterogeneity
.
Locus (genetics)
In the fields of genetics and genetic computation, a locus is the specific location of a gene or DNA sequence on a chromosome. A variant of the DNA sequence at a given locus is called an allele. The ordered list of loci known for a particular genome is called a genetic map...
(or gene
Gene
A gene is a molecular unit of heredity of a living organism. It is a name given to some stretches of DNA and RNA that code for a type of protein or for an RNA chain that has a function in the organism. Living beings depend on genes, as they specify all proteins and functional RNA chains...
) cause the same disorder
Genetic disorder
A genetic disorder is an illness caused by abnormalities in genes or chromosomes, especially a condition that is present from before birth. Most genetic disorders are quite rare and affect one person in every several thousands or millions....
. For example, β-thalassemia
Beta-thalassemia
Beta-thalassemias are a group of inherited blood disorders caused by reduced or absent synthesis of the beta chains of hemoglobin resulting in variable phenotypes ranging from severe anemia to clinically asymptomatic individuals. The total annual incidence of symptomatic individuals is estimated...
may be caused by several different mutations in the β-globin gene. It is a type of genetic heterogeneity
Genetic heterogeneity
Genetic Heterogeneity is a phenomenon in which a single phenotype or genetic disorder may be caused by any one of a multiple number of alleles or non-allele mutations. This is in contrast to pleiotropy, where a single gene may cause multiple phenotypic expressions or disorders...
.