Allelic heterogeneity - different mutations at a single locus
Anticipation - refers to the worsening of the symptoms of disease in succeeding generations
Biologic fitness - ability of an individual to produce children who survive to adult life and reproduce
Chromosomal disorders - involving the lack, excess, or abnormal arrangement of one or more chromosomes
Complex trait - multiple genes and factors are involved
Concordant - share a particular trait
Congenital - simply means present at birth
Discordant - do not share a particular trait
Dominant - genetic trait when only one abnormal gene is present and the corresponding allele on the homologous chromosome is normal
Epigenetic events - changes such as those involving methylation patterns
Expressivity (variability in clinical expression) - describes the range of phenotypic effects in individuals carrying a given mutation
Familial - trait or disorder tends to cluster in families
Genetic disorder - evidence that a gene or chromosome is involved in the susceptibility to the disease
Genetic heterogeneity - single genes have a predominant effect but the gene involved can vary from family to family
Genomic imprinting - different phenotypes according to its parent of origin
Heterozygous - two alleles are different
Homozygous - two alleles are identical
Imprinting - differential expression of the maternal and parental copy of a gene
Inherited - evidence for vertical transmission (e.g. father to daughter)
Lyon hypothesis (lyonization) - one X-chromosome active, the other inactivated; X-inactivation occurs early in embryonic development; inactive X-chromosome can be maternal or paternal in origin, choice of X-chromosome to be inactivated is random with respect to origin and independent of choice of other embryonic cells; X-inactivation is irreversible in somatic cell and remains so
Major gene - one gene dominates but the phenotype is dependent on other genes and factors
Multifactorial (complex disease traits) - involves a combination of environmental and genetic factors
Mutation - stable, heritable change in DNA, implies a change in primary nucleotide sequence
Nonallelic (locus) heterogeneity - mutations at different genetic loci
Nonrandom (skewed) X-inactivation (lyonization) - during early embryonic development in somatic cells of female one X chromosome is nonrandomly inactivated
Pedigree symbols -
Penetrance - the proportion of individuals with a given genotype who present with any phenotypic features of the disorder
Recessive - genetic trait when both alleles at a particular genetic locus are mutant
Sporatic - evidence for vertical transmission or familial clustering is lacking
Single gene (Mendelian) - one gene is responsible for trait with some modifications by other factors (autosomal dominant, autosomal recessive, or X-linked)
Variable expressivity - random variation in severity with succeeding generations
Uniparental disomy - inherit two copies of part or all of a chromosome from one parent and no copy from the other parent
X-inactivation (lyonization) - during early embryonic development in somatic cells of female one X chromosome is randomly inactivated
X-linked - genetic trait associated with X chromosome
Biochemistry
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