Null allele

A null allele is an allele, the effect of either the absence of a gene on the molecular level or the absence of a function on the Phänotypebene.

One example is the human blood groups A, B and 0 The alleles for the A and the B antigen are co-dominant, so both will be expressed when both exist. 0, however, the allele is identical to the A antigen allele, however, a base substitution mutation, probably. The so- encoded protein is dysfunctional, which phenotypically resulting in an absence of any antigen. Consequently, a group -0 allele is a null allele type.

In terms of genetic markers is null alleles at the loss of a marker, such as microsatellites, by mutation during the PCR process. By changing the sequence to which the primer binds, the corresponding portion can not be amplified and from the allele is a null allele. This can lead to misinterpretation eg in paternity analysis.

• Genetics