Medical Genetics & Cancer

monozygotic (MZ) twins

Twins that are genetically identical because they were formed from the same sperm and egg.

dizygotic (DZ) twins

Fraternal twins formed from separate pairs of sperm and egg cells.

concordance

The degree to which pairs of individuals (e.g. MZ or DZ twins) exhibit the same trait.

loss of heterogeneity

The phenomenon in which a particular type of disease or trait may be caused by mutations in two or more different genes.

founder

An individual who lived many generations ago and in whom a genetic disease originated.

linkage disequilibrium

The association of alleles and molecular markers with each other at a frequency that is significantly higher than expected by random chance.

GWAS

An examination of a genome-wide set of genetic variants among many individuals to see if any variant is associated with a disease or trait.

genetic testing

The analysis of individuals with regard to their genes or gene products.

genetic screening

The use of testing methods to determine if an individual is a heterozygous carrier or has a genetic disease.

amniocentesis

Method of obtaining cellular material from a fetus for the purpose of genetic testing.

chorionic villus sampling

Method for obtaining cellular material from a fetus for the purpose of genetic testing.

pre-implantation genetic diagnosis (PGD)

A form of genetic testing in which an embryo obtained via in vitro fertilization is tested for genetic abnormalities.

cancer

A disease characterized by uncontrolled cell division.

benign

A tumor that is not invasive and cannot metastasize.

malignant

A tumor that is invasive and can metastasize.

invasive

A tumor that can invade surrounding tissue.

metastatic

Cancer cells that migrate to other parts of the body.

carcinogen

An agent that can cause cancer.

oncogene

A gene that promotes cancer due to a gain-of-function mutation.

proto-oncogene

A normal cellular gene that may incur a gain-of-function mutation and lead to cancer.

growth factors

Protein factors that promote cell division.

transformation

When a normal cell is converted into a malignant cell.

tumor-suppressor genes

A gene that functions to inhibit cancerous growth.

apoptosis

Programmed cell death.

genome maintenance

Cellular mechanisms that prevent mutations from occurring and/or prevent mutant cells from surviving.

loss of heterozygosity

When a heterozygous somatic cell incurs a genetic change that inactivates the single functional allele.

correlation coefficient

A statistic that describes how two factors vary relative to each other, ranging between -1 and 1.

association

A relationship between variables in which changes follow a pattern.

personalized medicine

The application of genetic or molecular data in the treatment of disease.

molecular profiling

Methods that enable researchers to understand molecular changes in diseases such as cancer.

pharmacogenetics

The study or clinical testing of genetic variation that causes differing responses to drugs.