Involvement of a palindromic chromosome 22-specific low-copy repeat in a constitutional t(X; 22)(q27;q11).
Segmental duplications or low-copy repeats (LCRs) on chromosome 22q11 have been implicated in several chromosomal rearrangements. The presence of AT-rich regions in these duplications may lead to the formation of hairpin structures, which facilitate chromosomal rearrangement. Here we report the involvement of such a low-copy repeat in a t(X;22) associated with a neural tube defect. Molecular analysis of the chromosomal breakpoints revealed that the chromosome 22 breakpoint maps in the palindromic non-AT-rich NF1-like region of low-copy repeat B (LCR-B). No palindromic region was encountered near the breakpoint on chromosome X. Our findings confirm that there is no single mechanism leading to translocations with chromosome 22q11 involvement. Because LCR-B does not contain genes involved in neural tube development, we believe that the gene responsible for the observed phenotype is most likely localized on chromosome X.
Debeer
P
P
Laboratory for Molecular Oncology and Center for Human Genetics, Herestraat 49, B-3000 Leuven, Belgium.
Mols
R
R
Huysmans
C
C
Devriendt
K
K
Van de Ven
W J M
WJ
Fryns
J-P
JP
D001483:Base Sequence; D002892:Chromosomes, Human, Pair 22; D041321:Chromosomes, Human, X; D004247:DNA; D006801:Humans; D017404:In Situ Hybridization, Fluorescence; D008969:Molecular Sequence Data; D016133:Polymerase Chain Reaction; D012091:Repetitive Sequences, Nucleic Acid; D014178:Translocation, Genetic
D004247:DNA