title: Detection of microdeletions in the short arm of the X chromosome by chromosome stretching.
abstract: The present study was focused on the resolution of "chromosome stretching". In order to determine if this method can be used for the detection of microdeletions, the p-arms of 13 normal X chromosomes were stretched as well as of those with three different deletions of known size within the DMD/BMD region in Xp21 (case A: 0.42-0.45 Mb, case B: 2.3-2.9 Mb and case C: 3.0-3.5 Mb). The process of band splitting was recorded on a video-tape and the resulting banding pattern analyzed. Stretching of the normal Xp-arms led to a splitting on a maximum band level of 1400 and showed in all cases an identical banding pattern with 13 Giemsa-dark subbands. All new Giemsa-dark and -light subbands were derived from the three initial Giemsa-dark bands at the 400 band level according to ISCN (1995): five subbands from Xp21, four subbands from Xp11.3 and Xp22.2, respectively. The origin of these subbands is partly in contrast to the high resolution ISCN (1995) ideograms: subband Xp11.22 does not originate from the Giemsa-light band Xp11.2, but from the Giemsa-dark band Xp11.3; Xp22.12 originates from Xp21; Xp22.32 from Xp22.2. Stretching of the chromosomes containing deletions showed in cases A and B no differences in banding patterns and splitting order compared to normal X chromosomes. Only in patient C was a significant difference with the normal pattern visible due to the absence of one dark subband. In this case only four Giemsa-dark subbands derived from band Xp21. Thus, at least in the DMD/BMD region, the minimal size of a deletion detected by chromosome-stretching-generated high-resolution ideograms is about 3.0-3.5 Mb.
authors.affiliation: Institute of Human Genetics and Anthropology, Jena, Germany. almu@mti-n.uni-jena.de
authors.forename: A
authors.initials: A
authors.lastname: Kuechler
authors.forename: C R
authors.initials: CR
authors.lastname: Mueller
authors.forename: T
authors.initials: T
authors.lastname: Liehr
authors.forename: U
authors.initials: U
authors.lastname: Claussen
mesh_terms: D001399:Azure Stains; D002871:Chromosome Banding / Q000379:methods; D002872:Chromosome Deletion; D020732:Cytogenetic Analysis / Q000379:methods*; D006801:Humans; D008297:Male; D020388:Muscular Dystrophy, Duchenne / Q000235:genetics*; D018583:Pliability; D017384:Sequence Deletion / Q000235:genetics*; D014960:X Chromosome / Q000235:genetics*
chemical_list: D001399:Azure Stains