Characterization and clinical implications of marker chromosomes identified at prenatal diagnosis.
Eighteen fetuses with marker chromosomes were detected at diagnostic amniocentesis in our laboratory among 15 781 amniocentesis samples. Using combined approaches, conventional cytogenetics including special stain techniques and fluorescence in situ hybridization (FISH), we successfully characterized 15 of them, which assisted subsequent genetic counselling. Six marker chromosomes were of sex chromosome origin, each of which substituted a missing sex chromosome, and 12 were supernumerary marker chromosomes (SMCs). Nine of the SMCs were proven to be of autosomal origin. Of those autosomal SMCs, five originated from chromosome 15, two from chromosome 18, one from chromosome 12 and one from chromosome 1. Among 16 marker chromosomes with adequate follow-up information, 50% were benign including four sex chromosome markers and four autosomal markers. Two thirds of de novo marker chromosomes were associated with abnormal outcomes, while all inherited ones were benign regardless of their parental origin. Our study demonstrated that molecular characterization of prenatal marker chromosomes is of great significance in facilitating phenotype-genotype correlation.
Li
M M
MM
Cytogenetics laboratory, Genetics & IVF Institute, Fairfax, VA, USA. Hmliu2ssmd@aol.com
Howard-Peebles
P N
PN
Killos
L D
LD
Fallon
L
L
Listgarten
E
E
Stanley
W S
WS
D000649:Amniocentesis; D002869:Chromosome Aberrations; D002881:Chromosomes, Human, Pair 12; D002884:Chromosomes, Human, Pair 15; D002887:Chromosomes, Human, Pair 18; D005260:Female; D005819:Genetic Markers; D006801:Humans; D017404:In Situ Hybridization, Fluorescence; D018404:Isochromosomes; D008297:Male; D011247:Pregnancy; D062085:RNA, Long Noncoding; D022661:RNA, Untranslated; D012729:Sex Chromosome Aberrations; D014157:Transcription Factors / Q000235:genetics; D014424:Turner Syndrome / Q000175:diagnosis / Q000235:genetics; D014960:X Chromosome
D005819:Genetic Markers; D062085:RNA, Long Noncoding; D022661:RNA, Untranslated; D014157:Transcription Factors; C077885:XIST non-coding RNA