Genetics Flashcards
What three factors can cause disease?
Genetics, Multifactorial or Enviromental
What is a Autosome?
Any chromosome, other than the sex chromosomes (X or Y), that occurs in pairs in diploid cells
What is a recessive gene?
Phenotype manifest only in homozygotes
What is an Allele?
One or more alternative forms of a gene at a given location (locus)
What is homozygous?
Presence of identical alleles at a given locus
What is heterozygous?
alleles at a locus are different
What is allelic heterogeneity?
The situation where different mutations within the same gene result in the same clinical condition
What is consanguinity?
Reproductive union between two relatives
What is autozygosity?
Homozygosity by descent, i.e. inheritance of the same altered allele through two branches of the same family.
What is penetrance?
The percentage of individuals with a specific genotype showing the expected phenotype
What is expressivity?
Refers to the range of phenotypes expressed by a specific genotype
What is anticipation?
Whereby genetic disorder affects successive generations earlier or more severely, usually due to expansion of unstable triplet repeat sequences
What is Somatic Mosaicism?
Genetic fault present in only some tissues in body.
What is Gonadal (germline) Mosaicism?
Genetic fault present in gonadal tissue
What is Late-onset?
Condition not manifest at birth (congenital), classically adult-onset
What is sex-limited?
Condition inherited in AD pattern that seems to affect one sex more than another
What is predictive testing?
Testing for a condition in a pre-symptomatic individual to predict their chance of developing condition
What is Lyonization?
Generally only one of two X chromosomes active in each female cell. Can be skewed (X inactivation)
Where is mitochondrial DNA inherited from?
The Mother
What is homoplasmy?
a eukaryotic cell whose copies of mitochondrial DNA are all identical (identically normal or have identical mutations)
What is heteroplasmy?
there are multiple copies of mtDNA in each cell
What is genotype?
genetic constitution of an individual
What is phenotype?
appearance of an individual (physical, biochemical, physiological) which results from the interaction of the environment and the genotype
What is polymorphism?
Frequent hereditary variations at a locus
What is hemizygous?
only one allele refers to a locus on an X chromosome in a male
What is Autosomal Dominance Inheritance?
Disease which is manifest in the heterozygous state
What is Autosomal Recessive Inheritance?
Disease which is manifest in the homozygous state
What is X-Linked Recessive Inheritance?
Caused by pathogenic variants in genes on the X chromosome
What is Multifactorial conditions?
Diseases that are due to a combination of genetic and environmental factors
