Birth Defect Terms and Definitions

Centromere
A specialized chromosome region to which spindle fibers attach during cell division.

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

Single-gene disorder
Hereditary disorder caused by a mutant allele of a single gene.

Mutation
Any heritable change in DNA sequence.

Deletion.
A loss of part of the DNA from a chromosome; can lead to a disease or abnormality.

Phenotype
The physical characteristics of an organism or the presence of a disease that may or may not be genetic.

Cancer
Diseases in which abnormal cells divide and grow unchecked.

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.

Hybrid
The offspring of genetically different parents.

Risk communication
In genetics, a process in which a genetic counselor or other medical professional interprets genetic test results and advises patients of the consequences for them and their offspring.