null allele


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Related to null allele: Null mutation

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.
References in periodicals archive ?
It may be due to the presence of low frequency null alleles segregating at these loci as described by Peter 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.
The molecular basis of a microsatellite null allele from the White Sands pupfish.
The null alleles affect population parameters which are estimated based on the proportion of heterozygotes.
Genetic parameters at the eight microsatellite loci, number of alleles per locus (N), percentage of polymorphic loci (P), observed ([H.sub.o]) and expected ([H.sub.e]) heterozygosity, estimated frequencies of null alleles (r) and polymorphic information content (PIC), calculated by grouping all of the cultivars into one group.
Comparing these data and our results using a population of 60 Mexicans with chronic periodontitis, an increase in the frequency of the GSTM1 null allele to 55% is observed and our data indicate that the GSTT1 null allele is present at a frequency of 65%.
Taken together, the observations from the genetic crosses described above and the cuticle analyses suggest that the [hth.sup.CPTI000378] allele is not a null allele and support the view that the [hth.sup.CPTI000378] lethality is likely due to a second site mutation.
All apparently homozygous undisputed mothers who had a different STR phenotype to their apparently homozygous children were counted as probable null allele carriers.
Allelic frequencies of esterase loci determined for populations and clones of Schizaphis graminum Region Null Allele Allele 1 Allele 2 Allele 3 A 0 0.5 0.5 0 B 0.28 0.71 0 0 C 0.24 0.34 0.34 0.08 D 0.24 0.16 0.28 0.16 E 0.23 0.19 0.41 0.16 E1 0 0.5 0.5 0 F 0.25 0.26 0.40 0 F1 0.74 0.2338 0.024 0 G 0 0.015 0.09 0.22 Region Allele 4 Allele 5 Allele 6 Allele 7 A 0 0 0 0 B 0 0 0 0 C 0 0 0 0 D 0.16 0 0 0 E 0 0 0 0 E1 0 0 0 0 F 0 0 0 0 F1 0 0 0 0 G 0.22 0.317 0.015 0.11 Table III.
When Shriver, who considers himself to be white, analyzed his own DNA, he found that it contained the Duffy null allele, found only in descendants of sub-Saharan Africans.