[NEMO Delta 4-10 deletion of NEMO gene in Chinese incontinentia pigmenti cases]

Abstract

Objective: Incontinentia pigmenti (IP) is a rare X-linked dominant disorder that affects ectodermal tissues. In IP, mutations in NEMO lead to the complete loss of NF-kB activation creating a susceptibility to cellular apoptosis in response to TNF-alpha. Recently, a second nonfunctional copy of the gene, Delta NEMO was identified, opposite in direction to NEMO. Almost 90% of IP whose gene mutation type had been recognized have a recurrent genomic deletion of exons 4-10 of the NEMO (IKK gamma) gene, called NEMO Delta 4-10, which is necessary to activate the NF-kB pathway. Therefore, PCR-based detection of the NEMO deletion is a diagnostic measurement for IP. This study sought to analyze the NEMO Delta 4-10 deletion in NEMO gene of Chinese IP cases.

Methods: Seven IP cases and part of their families totally 15 persons were enrolled in this study. The 7 IP cases were aged 41 days to 8 years. Among them 1 was male and 6 were female. Four cases had family history of IP, the other 3 were sporadic cases. Fifty healthy children without any congenital diseases were taken as normal control group. According to the gene characteristics of IP, by PCR measurement NEMO Delta 4-10 deletion in NEMO gene was tested with specific primers In2/JF3R, and NEMO Delta 4-10 deletion in pseudogene Delta NEMO was checked out by primers Rev-2/JF3R.

Results: Five out of the 7 tested cases (case 1, 2, 3, 4, and 6) showed NEMO Delta 4-10 deletion in NEMO gene. The mothers of case 1 and case 6, 1a and 6a, also suffered from this disease, and their results were just the same as their daughters. For pseudogene Delta NEMO only case 2 and case 4 were proved having NEMO Delta 4-10 deletion, while other cases and families had negative results. For normal control group, NEMO Delta 4-10 deletion was not found either in NEMO gene or in their pseudogene Delta NEMO.

Conclusion: Incontinentia pigmenti in most cases were caused by NEMO Delta 4-10 deletion in NEMO gene.