• Contact Us

    Newborn Screening Unit
    Genetic Services
    PO Box 149347, MC-1918
    Austin, Texas 78714-9347

    Fax: 512-776-7593
    Toll-free: 800-252-8023


Genetics Definitions

  • Allele - Different versions of a trait, like brown or blue for eye color.
  • Benign - A type of tumor where the growth is controlled and eventually stops. This results in an encased pile of cells like a wart.
  • Carrier - A type of genetic makeup when one person has two different alleles, a dominant and a recessive. For albinism, if someone has the albino trait and the skin pigment trait, they will have skin pigment, but "carry" the albino trait so that they may pass it on to their children.
  • Chromosome - A very tight package of DNA inside cells. Humans have two pairs (or sisters) of 23 of these packages of DNA that will tell a cell how to make all the proteins it needs.
  • DNA (Deoxyribonucleic Acid) - A molecule made out of two strands that are tied together by hydrogen bonds. Each strand is made up of a sugar, a phosphate group and one of four bases (adenine, guanine, cytosine or thymine). The organization of these bases down the strand code for the synthesis of a cell's proteins.
  • Dominant - When one allele will ALWAYS show up if it is inherited, regardless of the other allele a person receives from sister chromosome. For instance, a person who receives at least one allele coding for skin pigment can not be an albino, even if the other parent passes on the albino gene.
  • Gene - A segment of a chromosome that will code for one specific protein. A gene is responsible for a single trait that an organism will have, like the protein responsible for eye color. 
  • Malignant - A type of tumor where the genes that control growth have been mutated and a cell begins to grow uncontrollably.
  • Meiosis - A type of cell division when the cell decreases the number of chromosomes it has by half. In humans only the cells that make eggs and sperm do this. They do this so that when they come together during fertilization, the baby will have a complete set of two of each of the 23 chromosomes.
  • Metastasis - When a malignant tumor gains the ability to move out of its current tissue and into the blood stream. This allows it to spread to different parts of the body.
  • Mutation - A disruption in the normal sequence of a DNA strand resulting in a different trait produced. Albinism is an example, where a protein involved in making skin pigment is made differently and does not function properly. This gives the light skin, light hair and red eye color.
  • Nondisjunction - An event that can occur during meiosis where the chromosomes don't separate properly. It results in the developing egg or sperm cell having too many or too few chromosomes.
  • Recessive - When one allele will ONLY show up if two copies are inherited. For example, a person who receives the albino allele for skin pigment from one parent will only be albino if the allele from the other parent is an albino allele as well.
  • Trait - The physical result that is produced when a cell's gene is read and protein is made, such as the type of hair a person has.
  • Tumor - An abnormal growth of tissue that causes cells to grow on top of one another.
Last updated April 29, 2022