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Polymerase chain reaction


A tool used to diagram genetic relationships in a family. Standard symbols are used to record the medical history and trace the inheritance of a disease or trait in a family.


The proportion of individuals with a genotype who express the clinical symptoms of the disorder. Complete penetrance indicates all individuals with the genotype display symptoms of the disorder. Incomplete penetrance indicates only some of the individuals with the genotype display symptoms of the disorder. Applies to autosomal dominant conditions. Contrast with Expressivity.

Personalized Genomic Medicine (PGM):

The tailoring of medical treatment and health decisions based on an individual’s genetic makeup.

Pharmacogenetics (PGx):

The study of how genetics impacts an individual’s response to medication. Often used interchangeably with “pharmacogenomics.”


A trait or phenotype which mimics a trait or phenotype, but is caused by another gene or environmental factor.


The observable physical , biochemical, and physiological traits of an individual which may or may not be determined by genes and/or environmental factors. Examples of phenotype include eye color, height, blood type, and hearing loss.

Point mutation:

The alteration of a single nucleotide in the DNA sequence.


DNA sequence alterations which result in differences among individuals within a population. These DNA variants are common in the general population and result in natural variations in genes. In general, polymorphisms are considered to be common and have no adverse effect on an individual. Polymorphisms are useful for creating genetic maps of populations.

Private mutation:

A rare DNA alteration which may be exclusively found in a single family or population.


The affected individual by which a family with a genetic disorder is ascertained (in a family to present to medical attention). Also called the propositus or index case.