null allele

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null allele

A segment of DNA which is not known to encode a protein product.

null allele

a form of a gene whose product is either absent at the molecular level, or is present but has no measurable phenotypic function. For example, in a heterozygote with INCOMPLETE DOMINANCE one gene form is a ‘null allele’ and is inactive, while the other allele is unable to compensate for the null allele and so produces an intermediate phenotype.

allele

one of two or more alternative forms of a gene at the same site or locus in each of a pair of chromosomes, which determine alternative characters in inheritance. Called also allelomorph.

blank allele
an allele which produces an antigen which cannot be detected.
null allele
see silent allele (below).
silent allele
one that produces no detectable effect.
References in periodicals archive ?
This phenomenon may result from inbreeding, natural selection, null alleles, and genetic drift (Lowe et al.
Null alleles were detected only in one locus (Sat 5) in individuals from Santa Maria del Mar.
However, the presence of null alleles was observed only in Bh8, and probably should not have affected genetic variability in this case.
Of the 7 microsatellites analyzed, the locus Obo19TUF consistently showed the presence of null alleles in all sample sites, thus this locus was eliminated from the analyses.
These results are consistent with a previously inferred prevalence of null alleles (Ewers-Saucedo et al.
These mismatches can be ascribed to the presence of allelic drop-out, null alleles or high frequency of mutations resulting in 2-4 bp shifts.
Null alleles were detected at three loci (AV13, MSMM2, and MSMM6), but because they were not consistently detected across all subspecies (Appendix II) we used all loci in subsequent analyses.
Effects of microsatellite null alleles on assignment testing.
Screening of data for large allele dropout, null alleles and scoring errors was carried out using MicroChecker (Van Oosterhout et al.
Three loci displayed significant departure from Hardy-Weinberg equilibrium expectations, likely reflecting occurrence of null alleles.