Premium
Intrachromosomal insertion mimicking a pericentric inversion: Molecular cytogenetic characterization of a three break rearrangement of chromosome 20
Author(s) -
Ardalan Azarnouche,
Prieur Marguerite,
Choiset Agnès,
Turleau Catherine,
Goutieres Françoise,
GirardOrgeolet Sylvie
Publication year - 2005
Publication title -
american journal of medical genetics part a
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.064
H-Index - 112
eISSN - 1552-4833
pISSN - 1552-4825
DOI - 10.1002/ajmg.a.30966
Subject(s) - chromosomal inversion , biology , gene duplication , genetics , breakpoint , fluorescence in situ hybridization , chromosomal rearrangement , chromosome 22 , karyotype , gene rearrangement , chromosome , chromosome 17 (human) , chromosome 4 , chromosome 9 , cytogenetics , chromosomal translocation , gene
Intrachromosomal insertions are uncommon rearrangements, in which a chromosomal segment is intercalated into another part of the same chromosome. The insertion may occur in the same arm (paracentric) or in the other arm (pericentric). The cytogenetic recognition of these structurally rearranged chromosomes can be difficult, and intrachromosomal insertions can be easily mistaken for inversions. We describe a case of a familial pericentric insertion of chromosome 20, initially misdiagnosed as a pericentric inversion in the healthy carrier and then reinterpreted as insertion in an abnormal child with a recombinant chromosome. Fluorescence in situ hybridization (FISH) allowed us to confirm the mechanism of recombinant formation and to locate the three breakpoints precisely. Our cytogenetically unbalanced epileptic patient carried a 20q deletion and 20p duplication, and the genes, CHRNA4 and KCNQ2 that have been implicated in autosomal dominant epilepsy, were deleted. The haplo‐insufficiency of these two genes may contribute to the cause of epilepsy in patients with ring chromosome 20. © 2005 Wiley‐Liss, Inc.