About psoriasis
Glossary

• Angiogenesis: formation of new blood vessels in the body; thought to be involved in the development of psoriasis lesions.
  

• Antibody: a protein produced by the immune system cells that binds to antigens so other elements of the immune system can attack and destroy or remove the antigen.
  

• Antigen: a large molecule or small organism, such as the strep throat bacterium, whose entry into the body provokes an immune-system response.
  

• Antisense: man-made DNA designed to bind to natural RNA within cells to prevent the production of a protein involved in psoriasis.
  

• Biotechnology: a set of techniques, such as those used to make DNA in laboratories, developed through basic research that are now used by companies to make new drugs.
  

• Candidate genes: genes that are potentially linked to a disease

• Cell: A cell contains all of the genetic information it takes to make a human being. The cell nucleus contains 23 pairs of chromosomes (one half of each pair is inherited from each parent).
  

• Chimera: a molecule that contains genetic material from two species, e.g., mouse and human.
  

• Chromosome: a structure composed of DNA and proteins that bears part of the genetic information of a cell.
  Each chromosome contains hundreds to thousands of individual genes, which give people their distinct characteristics. Each human has about 30,000 to 35,000 genes in total. Genetic information is encoded in long strands of a chemical called deoxyribonucelic acid (DNA), which is shaped in two connected strands that look like a twisted ladder (the shape is called a "double helix").
  

• Cytokine: proteins used by the immune system to communicate messages between cells; in psoriasis, cytokines carry messages that promote inflammation and the overly rapid development of skin cells.
  

• Deoxyribonucleic acid (DNA): fundamental hereditary material of all living organisms; stored primarily in the cell's nucleus

• Fusion protein: parts of fully human amino acid sequences fused together into one protein; can be used to block the interaction between two cells.
  

• Gene: a unit of heredity; a sequence of DNA containing biologically useful information

• Genes and base pairs: Genes are arranged like beads on a string—they are short sections of DNA that hold the "recipe" for a specific protein or molecule. The recipe is spelled out by the arrangement of four chemicals that connect the strands of DNA in pairs ("base pairs").
  

• Inflammation: reaction by tissue, e.g., skin, in response to infection or injury.
  

• Immune system: complex group of cells and organs that defend the body against infection and disease

• Interleukin: cytokines that stimulate the growth and maturation of cells of the immune system.
  

• Keratinocyte: a type of skin cell; hyperproliferation (accelerated growth) of these cells leads to development of psoriasis lesions.
  

• Keratolytic: an agent that promotes the shedding of the epidermis at regular intervals.
  

• Lesion: patch of skin affected by psoriasis.
  

• Linkage: identification of genes that may be linked because they reside on the same chromosome

• Macrophage: also called an "antigen-presenting cell," macrophages destroy foreign antigens and initiate T cell formation.
  

• Mapping: Determination of the relative positions of genes on a DNA molecule (chromosome or plasmid) and of the distance, in linkage units or physical units, between them. In psoriasis research, scientists narrow their search for disease-related genes by looking for distinct sequences of base pairs ("markers") that seem to pass through family members in connection ("linked") with a genetic disease. Candidate genes that are linked to the marker can then be tested one by one.
  

• Marker: gene with a known location on a chromosome; used as a point of reference when doing linkage analysis

• Monoclonal antibody (MAb): antibodies created with biotechnology techniques in laboratories. MAbs are highly specific and "recognize" and target only one molecule, such as a receptor, or antigen.
  

• Plaque: a scaly patch formed on the skin by psoriasis. Can be used interchangeably with "lesion."
  

• Psoriasis: Psoriasis is a chronic, noncontagious genetic disease of the immune system that prompts skin cells to regenerate too quickly, causing red, scaly lesions that crack and bleed. It often affects the elbows, knees, scalp and torso but can appear anywhere on the body.
  

• Psoriatic arthritis: Psoriatic arthritis is an inflammatory disease which causes pain, stiffness and swelling in and around the joints. Ten percent to 30 percent of people with psoriasis also develop psoriatic arthritis.
  

• Receptor: structures on the surface of cells that serve as docking sites for other cells or signaling molecules to relay information or trigger a reaction.
  

• Remission: The period during which the symptoms of a disease decrease or subside.
  

• T cells: cells that either initiate the immune response (helper T cells) or actively target and destroy cells perceived as foreign (killer T cells).
  

• T-cell receptors: molecules on the surface of T cells that are the sites for macrophages to "present" antigens to the T cell and trigger an immune response.
  

• Tumor necrosis factor (TNF): a protein in the body involved in inflammatory processes. When overproduced in the body, it also damages tissue in and around the joints of people with psoriatic arthritis.
  

• White blood cell: cells that help the body fight infection and disease