ABSTRACT
We present seven families with a cytogenetic duplication of the short arm of chromosome 8 at band 8p23.1. The duplication has been transmitted from parents to offspring in four of the seven families. In three families, the source of the extra material and its euchromatic origin were established using FISH with a YAC which was mapped to 8p23.1 and a whole chromosome paint for chromosome 8. FISH signals from this YAC were significantly larger on the duplicated chromosome compared with the normal chromosome in all six family members tested. Comparative genomic hybridisation (CGH) on a representative subject was consistent with these results. The families were ascertained for a variety of mostly incidental reasons including prenatal diagnosis for advanced maternal age. The transmission of this duplication by multiple phenotypically normal family members with no history of reproductive loss suggests the existence of a novel class of 8p23.1 duplications, which can be regarded as euchromatic variants or duplications with no phenotypic effect.
Subject(s)
Chromosome Aberrations , Chromosomes, Human, Pair 8 , Gene Rearrangement , Multigene Family , Adult , Amniocentesis , Child , Chromosome Banding , Chromosome Mapping , Chromosomes, Artificial, Yeast , Down Syndrome/genetics , Female , Genetic Carrier Screening , Humans , In Situ Hybridization, Fluorescence , Karyotyping , Male , Pedigree , PregnancyABSTRACT
We describe a 17 year old male with a low level of trisomy 9 mosaicism. Maternal uniparental chromosome 9 disomy in the euploid cell line was shown to have arisen after postzygotic loss of the paternal chromosome 9 from the trisomic cell line by cytogenetic and molecular analysis. This is believed to be the first report of uniparental disomy for chromosome 9. In four of the 11 reported cases of mosaic trisomy 9 syndrome, including our patient, a maternally derived pericentric inversion of the heterochromatic area of chromosome 9 has been present in duplicate in the trisomic cell line. This may have implications for the counselling of patients with this common chromosomal variant.
Subject(s)
Abnormalities, Multiple/genetics , Chromosomes, Human, Pair 9 , Intellectual Disability/genetics , Mosaicism/genetics , Trisomy/genetics , Adolescent , Cell Line , Chromosome Inversion , Ear/abnormalities , Face/abnormalities , Humans , Male , Neck/abnormalitiesABSTRACT
We describe a method, termed reverse chromosome painting, which allows the rapid analysis of the content and breakpoints of aberrant chromosomes. The method involves the sorting of small numbers of the aberrant chromosome from short term blood culture preparations or cell lines by using bivariate flow karyotype analysis. The sorted chromosomes are amplified and biotin labelled enzymatically using a degenerate oligonucleotide-primed polymerase chain reaction (DOP-PCR), the product annealed to metaphase spreads from normal subjects, and hybridisation detected using fluorescence in situ hybridisation (FISH). We show the usefulness of this method for routine clinical cytogenetics by the analysis of cases involving an insertion, a deletion, a translocation, and two cases of a chromosome with additional material of unknown origin. The method has particular application for the rapid resolution of the origin of de novo unbalanced chromosome duplications.
Subject(s)
Chromosome Aberrations , Cytogenetics/methods , Adult , Base Sequence , Cells, Cultured , Child , Chromosome Banding , Chromosome Deletion , DNA , DNA Probes , Evaluation Studies as Topic , Female , Flow Cytometry , Fluorescence , Humans , Infant , Infant, Newborn , Karyotyping , Male , Molecular Sequence Data , Nucleic Acid Hybridization , Polymerase Chain Reaction , Pregnancy , Translocation, GeneticABSTRACT
We report the case of a mentally retarded male with a ring 17 chromosome who had subretinal drusen-like deposits in each eye. This is the second report of flecked retina in a patient with ring 17 chromosome, suggesting that there may be a causal relationship between abnormalities of chromosome 17 and retinal pigment epithelial or photoreceptor dysfunction.
