Incontinentia pigmenti (IP) is a rare, inherited, multisystem genodermatosis. It 
is transmitted as an X-linked dominant trait. The disorder is a consequence of 
mutations in the NEMO gene (Xq28) that completely abolish expression of the 
NF-kappaB essential modulator. Here we present a female infant of healthy 
nonconsanguinous, young parents with a clinically evident first phase of IP. PCR 
analysis of patient's peripheral blood lymphocytes DNA was done for detection of 
NEMO delta4-10 deletion. Skin changes present at birth appertain to first 
inflammatory stage. However, a pathohistological feature of the skin biopsy 
showed second phase of disease. Genetic testing of diseased child revealed 
delta4-10 in NEMO gene. However, the assumption that the female child has 
familial IP was rejected as PCR performed on the mother's leukocytes did not 
record the presence of the same mutation. Moreover, the existence of a healthy 
male infant of the same mother as well as the lack of any phenotypic signs of 
the disease in other family members additionally support that IP was not 
inherited, but it was a consequence of de novo NEMO gene mutation. In 
conclusion, here we describe a Croatian female with clinical IP phenotype having 
de novo genomic rearrangements in the NEMO gene.