The origin of cytologically unidentifiable chromosome abnormalities: six cases ascertained by targeted chromosome-band painting.
De novo chromosome structural abnormalities cannot always be diagnosed by the use of standard cytogenetic techniques. We applied a previously developed chromosome-band-specific painting method to the diagnosis of such rearrangements. The diagnostic procedures consisted of microdissection of an aberrant chromosomal region of a given patient, polymerase chain reaction (PCR) amplification of the dissected chromosomal DNA, and subsequent competitive fluorescence in situ hybridization (FISH) using the PCR products as a probe pool on metaphase chromosomes from the patient and/or a karyotypically normal person. With this strategy, we studied 6 de novo rearrangements (6p+, 6q+, 9p+, 17p+, +mar, and +mar) in 6 patients. These rearrangements had been seen by conventional banding but their origin could not be identified. In all 6 patients, we successfully ascertained the origin. Using an aberrant region-specific probe pool, FISH signals appeared on both the aberrant region and a region of another specific chromosome pair. A reverse probe pool that was generated through the microdissection of normal chromosomes at a candidate region for the origin of the aberration hybridized with both the aberrant and the candidate regions. We thus diagnosed one patient with 17p+ as having trisomy for 14q32-qter, one with 9p+ as having trisomy for 12pter-p12, one with 6q+ as having a tandem duplication (trisomy) of a 6q23-q25 segment, one with 6p+ as having a tandem duplication (trisomy) of a 6p23-q21.3 segment, one with a supernumerary metacentric marker chromosome as having tetrasomy for 18pter-cen, and the last with an additional small marker chromosome as having trisomy for 18p11.1 (or p11.2)-q11.2. The present targeted chromosome-band-painting method provides the simple and rapid preparation of a probe pool for region-specific FISH, and is useful for the diagnosis of chromosome abnormalities of unknown origin.
Ohta
T
T
Department of Human Genetics, Nagasaki University School of Medicine, Japan.
Tohma
T
T
Soejima
H
H
Fukushima
Y
Y
Nagai
T
T
Yoshiura
K
K
Jinno
Y
Y
Niikawa
N
N
D001483:Base Sequence; D002648:Child; D002869:Chromosome Aberrations / Q000175:diagnosis / Q000235:genetics*; D002871:Chromosome Banding / Q000379:methods*; D025063:Chromosome Disorders; D004247:DNA; D005260:Female; D006801:Humans; D017404:In Situ Hybridization, Fluorescence; D007621:Karyotyping; D008297:Male; D008969:Molecular Sequence Data
D004247:DNA