title: Microdeletion/duplication at the Xq28 IP locus causes a de novo IKBKG/NEMO/IKKgamma exon4_10 deletion in families with Incontinentia Pigmenti.
abstract: The Incontinentia Pigmenti (IP) locus contains the IKBKG/NEMO/IKKgamma gene and its truncated pseudogene copy, IKBKGP/deltaNEMO. The major genetic defect in IP is a heterozygous exon4_10 IKBKG deletion (IKBKGdel) caused by a recombination between two consecutive MER67B repeats. We analyzed 91 IP females carrying the IKBKGdel, 59 of whom carrying de novo mutations (65%). In eight parents, we found two recurrent nonpathological variants of IP locus, which were also present as rare polymorphism in control population: the IKBKGPdel, corresponding to the exon4_10 deletion in the pseudogene, and the MER67Bdup, that replicates the exon4_10 region downstream of the normal IKBKG gene. Using quantitative DNA analysis and microsatellite mapping, we established that both variants might promote the generation of the pathological IKBKGdel. Indeed, in family IP-516, the exon4_10 deletion was repositioned in the same allele from the pseudogene to the gene, whereas in family IP-688, the MER67Bdup generated the pathological IKBKGdel by recombination between two direct nonadjacent MER67Bs. Moreover, we found an instance of somatic recombination in a MER67Bdup variant, creating the IKBKGdel in an IP male. Our data suggest that the IP locus undergoes recombination producing recurrent variants that might be "at risk" of generating de novo IKBKGdel by NAHR during either meiotic or mitotic division.
authors: Institute of Genetics and Biophysics Adriano Buzzati-Traverso (IGB-CNR), Naples, Italy.
authors: Francesca
authors: F
authors: Fusco
authors: Mariateresa
authors: M
authors: Paciolla
authors: Alessandra
authors: A
authors: Pescatore
authors: Maria Brigida
authors: MB
authors: Lioi
authors: Carmen
authors: C
authors: Ayuso
authors: Francesca
authors: F
authors: Faravelli
authors: Mattia
authors: M
authors: Gentile
authors: Marcella
authors: M
authors: Zollino
authors: Michele
authors: M
authors: D'Urso
authors: Maria Giuseppina
authors: MG
authors: Miano
authors: Matilde Valeria
authors: MV
authors: Ursini
mesh_terms: D001483:Base Sequence; D041321:Chromosomes, Human, X / Q000235:genetics*; D005091:Exons / Q000235:genetics*; D005190:Family; D005260:Female; D020440:Gene Duplication; D006801:Humans; D051550:I-kappa B Kinase / Q000235:genetics* / Q000378:metabolism; D007184:Incontinentia Pigmenti / Q000235:genetics* / Q000378:metabolism; D008297:Male; D008957:Models, Genetic; D008969:Molecular Sequence Data; D010375:Pedigree; D017384:Sequence Deletion
chemical_list: C491731:IKBKG protein, human; D051550:I-kappa B Kinase