Cystic fibrosis.

A genetic disease that affects a number of organ systems, particularly the respiratory, gastrointestinal, and reproductive systems, and leads to early death.

Cytochrome P450.

Specific type of enzyme involved in the metabolism of foods, drugs, and environmental chemicals.


Cell containing double pairs of chromosomes in the nucleus. In general, all cells except the gametes (ovum and sperm) are diploid.


A precursor of dopamine used as a treatment for Parkinson's disease.


A neurotransmitter. Malfunction of dopamine cells in specific brain regions gives rise to Parkinson's disease.


Unborn conceptus in early weeks of pregnancy, usually up to the ninth week.


Proteins that induce chemical reactions in other molecules.


Unborn conceptus in later weeks of pregnancy, usually after ninth week.

Fluorescence in situ hybridization (FISH).

Technique for finding specific regions of DNA in a large mix (or in cells) by using chemically labeled, single strands of complementary nucleotide sequences to serve as probes that are detected by fluorescent compounds.

Fragile X syndrome.

The most common form of inherited mental retardation. (See X-linked diseases.)


Reproductive germ cell; a sperm is the male gamete, an oocyte the female gamete.

Gamma globulin. A preparation of blood proteins, containing antibodies, that can be administered to boost immune responses. Genome. The entire genetic repertoire of a cell. Graft-versus-host disease. Rejection of the recipient's body cells or tissues by the immune responses of the donor, a particular problem in transplantation of hematopoietic tissue such as bone marrow.
Haploid. Cell with a single set of chromosomes, as in sperm and oocytes. HDL. High-density lipoprotein. Lipoproteins are compounds of fats and proteins. In adults, HDL participates in cholesterol metabolism: in the uterus, HDL seems to regulate placental hormones involved in fetal growth.


Process though which precursor cells give rise to all the varieties of blood cells.

Hematopoietic stem cells.

Precursor cells that give rise to different blood cells and to other stem cells.


Area of the brain involved in memory formation.

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