A case of incontinentia pigmenti in Japan and its genetic examination

Purpose: Incontinentia pigmenti (IP) is a rare X-linked dominant genodermatosis with approximately one-third of cases with associated ocular complications. Deletion of exons 4 to 10 of the nuclear factor kappa B essential modulator (NEMO) gene accounts for the majority of new mutations. The disease is more commonly found among Caucasians. We studied a case of an IP patient in Japan, and the genomic rearrangements. Methods: An 11-month-old female infant exhibited the skin lesions of IP. Ocular findings were total retinal detachment with a retrolental fibrovascular mass in the right eye, and patchy retinal avascular zones and neovascularization in the left eye. The genomic rearrangement of NEMO was investigated by a polymerase chain reaction (PCR)-based diagnostic test. A skewed X-inactivation assay was also performed using the human androgen receptor gene as a genetic marker. Results: Deletion of exons 4 to 10 in NEMO was detected in the proband and in other female members of her family. A complete skewing of the X-inactivation pattern causing IP was observed, indicating cells having no protection against apoptosis in response to tumor necrosis factor as the pathogenicity of the disease. Conclusions: This is the first case report of a Japanese female phenotype demonstrating the common genomic rearrangement in the NEMO gene.