J Korean Med Sci.  2010 Oct;25(10):1513-1517. 10.3346/jkms.2010.25.10.1513.

The Common NF-kappaB Essential Modulator (NEMO) Gene Rearrangement in Korean Patients with Incontinentia Pigmenti

• Song MJ
• Chae JH
• Park EA
• Ki CS

• KMID: 2157858
• DOI: http://doi.org/10.3346/jkms.2010.25.10.1513

Abstract

Incontinentia pigmenti (IP) is a rare X-linked dominant disorder characterized by highly variable abnormalities of the skin, eyes and central nervous system. A mutation of the nuclear factor-kappa B essential modulator (NEMO) located at Xq28 is believed to play a role in pathogenesis and the mutation occurs mostly in female patients due to fatal consequence of the mutation in males in utero. This study was designed to identify the common NEMO rearrangement in four Korean patients with IP. Deletion of exons 4 to 10 in the NEMO, the most common mutation in IP patients, was detected in all of the patients by the use of long-range PCR analysis. This method enabled us to discriminate between NEMO and pseudogene rearrangements. Furthermore, all of the patients showed skewed XCI patterns, indicating pathogenicity of IP was due to cells carrying the mutant X chromosome. This is the first report of genetically confirmed cases of IP in Korea.

Keyword

Incontinentia Pigmenti; NEMO; IKBKG

MeSH Terms

Alleles
Asian Continental Ancestry Group/*genetics
Chromosomes, Human, X
Exons
Female
Humans
I-kappa B Kinase/*genetics
Incontinentia Pigmenti/*genetics/pathology
Polymerase Chain Reaction
Republic of Korea
*Sequence Deletion

Figure

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  Fig. 1 Clinical features of Patient 1. (A) Lower leg of Patient 1, showing the hyperpigmented lesion along with Blaschko's lines on the posterior part of the lower limbs. Fundus photographs of the left eye (B) and right eye (C), showing retinal hemorA rhage and macular hypopigmentation.

• 

  Fig. 2 Schematic representation of NEMO and ΔNEMO pseudogene location in Xq28. (A) NEMO gene (▭), ΔNEMO pseudogene (▒), (B) rearranged NEMO gene (▭), ΔNEMO pseudogene (▒). In multiplex PCR, forward primers are Int3s (5'-CCA CTC AGG GCT TAG AGC GC-3') and Rep3s (5'-CTC TTT TGA CAA GAA CAC CGG A-3'). Int3s, located within intron 3, matches with the wild-type and rearranged NEMO and pseudogene as well. Rep3s matches with two direct repeats (▸) on both the wild-type NEMO and pseudogene, while it matches with the unique remaining direct repeat on the rearranged NEMO and pseudogene. L2Rev (5'-TCG GAG ACA CAG GAA CCA GCA-3') is the reverse primer. In long-range PCR, In2 (5'-GAG GAC CAA TAC CGA GCA TC-3') and JF3R (5'-CTC GGA GAC ACA GGA ACC AGC A-3') primers amplify a 2.6-kb gene-specific band. JF3R and Rev-2 (5'-GCC ATC TGT TTT TGC GTG TG-3') primers reveal a 2.5-kb pseudogene-specific band.

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  Fig. 3 Representative results of multiplex-PCR and long-PCR analysis. (A) Multiplex PCR products in all participants and controls (C1, C2). A 1045-bp band corresponding to DNA amplification between the Int3s and L2Rev primers indicates the presence of the common rearrangement found only in IP affected individuals. A 733-bp product serves as an internal control of DNA amplification (Rep3s and L2Rev primers). (B) Result of long-range PCR analysis. The specific NEMO deletion corresponds to the 2.6-kb band (In2 and JF3R primers) detected in the patients as well as in the mother of Patient 3 (3-M). 3-F, the father of Patient 3.

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  Fig. 4 XCI analyses in affected female individuals. After digestion with HpaII, a PCR product is obtained from the inactive X chromosome only. The red star (⋆) in Patient 3 indicates the maternal allele (273-bp).

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