Dominant: A genetic trait is considered dominant if it is expressed in a person who has only one copy of that gene. (In genetic terms, a dominant trait is one that is phenotypically expressed in heterozygotes).
A dominant trait is opposed to a recessive trait which is expressed only when two copies of the gene are present. (In genetic terms, a recessive trait is one that is phenotypically expressed only in homozygotes).
Examples of dominant disorders include:
Achondroplasia (a common form of dwarfism with short arms and legs),
Familial hypercholesterolemia (high blood cholesterol leading to premature coronary artery disease),
Huntington disease (a form of progressive dementia from which the folk singer Woody Guthrie suffered),
Neurofibromatosis (NF1)(a neurologic disorder with an increased risk of malignant tumors), and
Polycystic kidney disease (of adult onset).
Most dominant traits are due to genes located on the autosomes (the non-sex chromosomes). An autosomal dominant trait typically affects males and females with equal likelihood and with similar severity. The gene responsible for it can be transmitted from generation to generation and each child born to someone with the gene has a 50:50 chance of receiving the gene and manifesting the disease.
Donor: The giver of a tissue or an organ, such as a blood donor or kidney donor.
- Donor insemination
Donor insemination: A procedure in which a fine catheter (tube) is inserted through the cervix (the natural opening of the uterus) into the uterus (the womb) to deposit a sperm sample from a man other than the woman’s mate directly into the uterus. The purpose of this procedure is to achieve fertilization and pregnancy. Donor […]
- Donor lymphocyte infusion
Donor lymphocyte infusion: (DLI) A cancer treatment in which lymphocytes from a bone marrow donor are infused into the person who received the original bone marrow transplant. The goal of donor lymphocyte infusion is to induce a remission of the cancer by a process called the graft-versus-tumor (GVT) effect. Donor lymphocyte infusion is basically meant […]
- Donor, universal
Donor, universal: A person who is type O in the ABO blood group system and negative for the RhD blood group antigen and can donate blood to all recipients.
Dopa: A precursor (forerunner) of dopamine, a key neurotransmitter (messenger) in the brain. Dopa is used in the treatment of Parkinson disease. Parkinson disease is believed to be related to low levels of dopamine in certain parts of the brain. When dopa is taken by mouth, it crosses through the blood-brain barrier. Once it has […]