The basic unit of genetic material, which is carried at a particular place on a chromosome.

Mutation due to fundamental intramolecular reorganisation of a gene.

Treatment directed to curing genetic disease by introducing normal genes into patients to overcome the effects of defective genes, using techniques of genetic engineering.

The techniques involved in altering the characteristics of an organism by inserting genes from another organism into its DNA.

Any of the embryonic cells that have the potential to develop into spermatozoa or ova.  The term is also applied to any of the cells undergoing gametogenesis and to the gametes themselves.

A malignant tumor that originates from undifferentiated embryonic germ cells.

The special connective tissue of the central nervous system, composed of different cells, including the oligodendrocytes, astrocytes, ependymal cells, and microglia, with various supportive and nutritive functions.  Glial cells outnumber the neurons by between five and ten to one, and make up some 40% of the total volume of the brain and spinal cord.

Any tumour of non-nervous cells (glia) in the nervous system.  The term is sometimes also used for all tumours that arise in the central nervous system, including astrocytomas, oligodendrogliomas, medulloblastomas, and ependymomas.  Tumours of low grade malignancy produce symptoms by pressure on surrounding structures; those of high-grade malignancy may be invasive.

Any of several hormones synthesised and released by the pituitary gland that act on the testes or ovaries (gonads) to promote production of sex hormones and either sperms or ova.

Any organ, tissue, or object used for transplantation to replace a faulty part of the body.

A condition that occurs following bone marrow transplantation and sometimes blood transfusion, in which lymphocytes from the graft attack specific tissues in the host.

Any of a group of white blood cells that, when stained with Romanowsky stains, are seen to contain granules in their cytoplasm.  They can be subclassified on the basis of the colour of the stained granules into neutrophils, eosinophils, and basophils.