Effects of genomic imprinting on quantitative traits

Abstract

Standard Mendelian genetic processes incorporate several symmetries, one of which is that the level of expression of a gene inherited from an organism's mother is identical to the level should that gene have been inherited paternally. For a small number of loci in a variety of taxa, this symmetry does not hold; such genes are said to be "genomically imprinted" (or simply "imprinted"). The best known examples of imprinted loci come from mammals and angiosperms, although there are also cases from several insects and some data suggesting that imprinting exists in zebra fish. Imprinting means that reciprocal heterozygotes need not be, on average, phenotypically identical. When this difference is incorporated into the standard quantitative-genetic model for two alleles at a single locus, a number of standard expressions are altered in fundamental ways. Most importantly, in contrast to the case with euMendelian expression, the additive and dominance deviations are correlated. It would clearly be of interest to be able to separate imprinting effects from maternal genetic effects, but when the latter are added to the model, the well-known generalized least-squares approach to deriving breeding values cannot be applied. Distinguishing these two types of parent-of-origin effects is not a simple problem and requires further research.

Paternal Genetic Contribution Influences Fetal Vulnerability to Maternal Alcohol Consumption in a Rat Model of Fetal Alcohol Spectrum Disorder

“…If so, this would indicate that the fetus remains epigenetically sensitive to alcohol beyond the early stages marked by preconception, implantation and gastrulation, as previously shown [26], [27]. While imprinting effects can often be confounded by maternal genetic effects on the intrauterine environment [28], [29], the alcohol-exposed BN/BN fetuses of this study shared the same intrauterine environment as the most vulnerable BN/SD but unlike BN/SD, exhibited the mildest bodyweight deficit. The possibility that imprinted loci contributing to bodyweight may influence the long-term effects of alcohol could be tested using novel candidate imprinted loci regulating bodyweight [24], [25].…”

Parent-of-origin effects on voluntary exercise levels and body composition in mice

“…Potential sources of variation underlying the distribution of complex traits include the inherited genetic contributions and/or environmental stimuli (acting at any time after formation of the zygote, or in some cases even before). In particular, parent-of-origin effects are defined by cases in which a phenotype follows either a maternal or paternal line, as opposed to standard Mendelian inheritance patterns (73,87).…”

One- and Two-Locus Population Models With Differential Viability Between Sexes: Parallels Between Haploid Parental Selection and Genomic Imprinting

“…While there has been much progress in understanding the evolution of genomic imprinting (Hunter 2007), including advances in modeling (Spencer 2000(Spencer , 2008, the population genetics theory of parental effects received less attention. Existing major-locus effect models of parental selection are single-locus, two-allele, and mostly concern uniparental (maternal) selection (Wright 1969;Spencer 2003;Gavrilets and Rice 2006;Santure and Spencer 2006), with only one specific case where the fitness effects of both parents interact studied by Gavrilets and Rice (2006).…”