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

• 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 heterogeniety

• 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 different individuals to see if any variant is associated with a disease or other type of 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 for 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

• 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 does not cause cancer but which may incur a gain-of-function mutation or become incorporated into a viral genome and thereby 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

• refers to cellular mechanisms that either prevent mutations from occurring and/or prevent mutant cells from surviving or dividing

loss of heterozygosity

• when a heterozygous somatic cell incurs a genetic change that inactivates the single functional allele

correlation coefficient

• a statistic with a value that ranges between –1 and 1. It describes how two factors vary relative to each other

association

• a relationship between variables in which changes in them 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 the molecular changes that occur in diseases such as cancer

pharmocogenetics

• the study or clinical testing of genetic variation that causes differing responses to drugs