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Many words that are used to describe IP are somewhat technical, and not easily understood by those who are not in the medical, or a related profession. It therefore becomes confusing to those who are trying to make sense of this disorder that either they or a member of their family have. I would like to attempt to define, in the simplest most easily understood way, those words that I am asked about most.


A prenatal test (typically done at 14 to 18 weeks gestation) in which cells from the amniotic fluid surrounding a fetus are removed in order to examine their chromosomes. After the IP gene has been isolated, it will be possible for an expectant mother to have amniocentesis (or Chorionic Villous Sampling [CVS]) to discover if the child she is carrying has the IP gene.


The primary central nervous system structure (situated in the skull) which sends out and receives messages to and from the rest of the body.

central nervous system

The parts of the body that includes the brain and the spinal cord.


One of 46 small separate strands of rod-shaped bodies, paired as 23 pairs, in the center of every complete cell which contains genes. Among these is one pair called the sex chromosomes, made up of X and Y chromosomes. These determine the gender of a person. XX is female and XY is male. IP is X-linked, meaning that an altered or 'mutant' gene is located on one of the X chromosomes. Therefore, a female with IP has one X with the IP gene and one X that is normal. Since the IP gene is dominant, the female with that chromosomal pair will be affected with IP. If a male has the IP gene on his one and only X chromosome, (he then has no normal X chromosomal information for that gene, and has a Y chromosome that contains no information for this gene) he will be affected and cannot survive.


In reproduction, the point at which a sperm fertilizes an egg


The act of identifying a disease from its symptoms and signs.


Problems in how the body functions. Health problems caused by mutations in the genes are referred to as genetic disorders. IP is a genetic disorder.


The biochemical material inside the nucleus of cells that carries genetic information.

dominant gene

Having power and influence. The gene for IP is a dominant gene. If the gene which causes IP is within each cell of a person, the resultant disorder will definitely show up and the person will have IP.


The developing organism in the first three months following conception.


Before birth the fetal stage from the end of the third month until birth.


The essential and minimal unit of genetic information. All living things are made up of cells. Inside each cell are chromosomes which contain genes. Genes contain the instructions for making the cells and for doing the work that goes on inside them. But the human body is very complicated, so it needs a lot of instructions. Genes contain these instructions and help to decide many traits such as your size, build, coloring, even whether you are male or female. Sometimes, as in the case of IP, a gene does not give the right instruction, and things go wrong. That is why IP is referred to as a genetic disorder, that is, it is based in and caused by an altered gene. Scientists think that humans have somewhere around 80,000 genes. For hundreds of years, people have known that traits can be inherited. They observed how looks were passed down from parents to children. They noticed how illnesses run in families.

genetic counseling

Education and guidance offered by professional advisors in order to help people make informed decisions based on genetic knowledge. Genetic counseling is intended to help a person understand the meaning of specific information about his or her genes, and the disorders that they cause.

genetic linkage study

Examination of the DNA of family members to determine who may be at risk for a genetic disorder occurring in the family tree. Doctors look for variations that appear consistently in the DNA of family members with the disorder. These DNA variations may or may not be related to the genetic disorder. In the case of a woman with IP, who has other family members with IP, it can sometimes be determined if IP is present in the embryo she is carrying.


The field of science that studies the natural differences and similarities which often, but not always, are passed from one generation to another through the genes.


The handing down of certain traits from parents to their offspring. The process of heredity occurs through the genes.

human genome project

The scientific mission to "read" the order of genes as they appear in the DNA of human chromosomes. The Human Genome Project actually is not one project, but rather many hundreds of separate research projects being conducted throughout the world. The objective is to create a directory of the genes that can be used to answer questions such as what specific genes do and how they work.


Lack of control. e.g. Incontinentia Pigmenti - lack of control of the color in the cells of the skin.

in vitro fertilization (IVF)

The mixing of eggs with sperm in a laboratory dish in order to achieve conception. (in vitro = [Latin:] in glass)


Changes that occur in a gene making it different from customary and 'normal', and sometimes resulting in an abnormality. IP is the result of a genetic mutation. A normal gene that changes and behaves abnormally.

optic nerve

The nerve that transmits sight impulses from the retina of the eye to the brain.


[from Latin: 'of pigment'] Pigment is the dye-like material in cells that provides color to skin, eyes, and hair.


Before birth


Part of the eye that receives the image and which is connected to the brain by the optic nerve.


Sudden attack; convulsion. Sometimes temporary loss of consciousness with muscle contractions possibly due to fit or generalized spasm of uncontrolled electrical activity from the brain.


Contraction of any muscle that is sudden and involuntary.


Male fertilizing fluid

spinal cord

Part of the central nervous system enclosed within the backbone. It transmits impulses to and from the brain.


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