The cause of Incontinentia Pigmenti has been traced to a defective gene on the X chromosome called NEMO. The NEMO gene is of less than average size, spanning about 23 thousand base pairs. The NEMO gene produces a protein that is essential for cells and defects in it result in IP. Males with cannot survive without a functioning NEMO gene, and thus die in utero. In females, some cells have a normal functioning NEMO gene (from the normal X chromosome) while other cells have a defective NEMO gene. Currently, it is thought that the symptoms of IP in females result from cells with a defective NEMO gene in the affected tissue. Now that the gene has been found, this view can be tested. The normal function of NEMO is to allow cells to respond to outside signals, such as growth factors. Follow this link to read more technical information on NEMO with links to references and DNA and protein sequence. In about 85% of families, the mutation in the NEMO gene that results in IP is identical, even though the families are unrelated. A portion of the NEMO gene is duplicated, and these duplicated parts can result in deletions that disrupt the NEMO gene's function. This is unusual in human genetic disorders (most of the time, the mutations are different in different families). The presence of a frequent mutation, however, allows for easier testing (see the testing page).
What is NEMO
NEMO stands for NF kappa B essential modulator. The gene is also known as IKKgamma or IKBKG, which is its "official" gene name. It is involved in a cellular process known as "signal transduction" where signals from outside the cell are transmitted to the nucleus of the cell to alter gene expression.
A Genetic Primer