Birth Defect Terms and Definitions

Junk DNA
Stretches of DNA that do not code for genes; most of the genome consists of so-called junk DNA which may have regulatory and other functions.

Gene
The fundamental physical and functional unit of heredity. A gene is an ordered sequence of nucleotides located in a particular position on a particular chromosome that encodes a specific functional product

Genetic illness
Sickness, physical disability, or other disorder resulting from the inheritance of one or more deleterious alleles.

Embryonic stem (ES) cells
An embryonic cell that can replicate indefinitely, transform into other types of cells, and serve as a continuous source of new cells.

Mutation
Any heritable change in DNA sequence.

Acquired genetic mutation
A change in the genetic structure that is neither inherited nor passed to offspring. Also called acquired mutations.

Mitosis
The process of nuclear division in cells that produces daughter cells that are genetically identical to each other and to the parent cell.

Syndrome
The group or recognizable pattern of symptoms or abnormalities that indicate a particular trait or disease.

Birth defect
Any harmful trait, physical or biochemical, present at birth, whether a result of a genetic mutation or some other nongenetic factor.

Amino acid
Any of a class of 20 molecules that are combined to form proteins in living things.