Homozygosis


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The following article is from The Great Soviet Encyclopedia (1979). It might be outdated or ideologically biased.

Homozygosis

 

the state of the genetic apparatus of an organism in which homologous chromosomes have the identical form of a given gene. The transition of a gene into the homozygous state leads to the manifestation in the organism’s structure and function (phenotype) of recessive alleles, whose effect in heterozygosis is suppressed by the dominant alleles. A test for homozygosis is the absence of splitting in certain forms of crossbreeding. A homozygous organism produces only one form of gamete for a given gene.

The Great Soviet Encyclopedia, 3rd Edition (1970-1979). © 2010 The Gale Group, Inc. All rights reserved.
References in periodicals archive ?
Indeed, recent studies have suggested that residual enzymatic activity exists in patients homozygous for the Q188R mutation (the classic form of the disease), whereas in patients with GALT gene deletion in homozygosis, an extremely rare mutation, the existence of residual GALT activity would be impossible.
Table 6 - Estimates of heterozygosis and homozygosis in the population studied
Our results show that the TT homozygosis is unfavorable from acognitive point of view.
With the loss of the p53 homozygosis, the damage DNA is not repaired and there is marked proliferation of the mutation, genomic instability and loss of important cell cycle control mechanisms, being the cell led to malignant transformation (SANCHEZSERVIN et al., 2009).
It is important to note that homozygosis on rare allele genotype A/A was not detected in any group of observed patients.
In order to maintain healthy laboratory rearing regimes, a number of factors should be taken into consideration, including deterioration, excessive homozygosis, or other divergences from the original population (Joslyn 1984).
Relation between yielding ability and homozygosis in barley crosses.
One triplet expansion [[(GCC).sub.7]] acts as a modifier of the dominant disease phenotype caused by expansion of more than 1 triplet [[(GCC).sub.7]/ [(GCC).sub.>7]] or, in homozygosis [[(GCC).sub.7]/[(GCC).sub.7]], as a mutation.
The ApoE ?4 allele in both homozygosis and heterozygosis increases the risk of developing AD.[45] The ?4 allele is associated with a higher risk of atherosclerosis and higher plasma levels of total cholesterol and LDL-C.[34] In addition, several other genes involved in cholesterol metabolism have been reported to be associated with AD including adenosine triphosphate-binding cassette subfamily A member 7,[46] clusterin, and sortilin-related receptor (SORL1).[34]
The mutations identified were homozygosis for p.Pro341Ser in one patient and compound heterozygosis for p.Arg229Gln and p.Ala284Val in six patients [42, 51].
Homozygosis for the MnSOD Val allele contributed to development of DN in Finnish and Swedish patients with type 1 diabetes (73).