Subject(s)
Chromosome Deletion , Chromosomes, Human, Pair 6/genetics , Comparative Genomic Hybridization , Developmental Disabilities/complications , Developmental Disabilities/genetics , Ehlers-Danlos Syndrome/complications , Ehlers-Danlos Syndrome/genetics , Adult , Child , Child, Preschool , Chromosome Banding , Chromosomes, Artificial, Bacterial/genetics , Female , Humans , Infant , Infant, Newborn , KaryotypingABSTRACT
OBJECTIVE: Prenatal diagnosis of foetal trisomies is usually performed by cytogenetic analysis. This requires lengthy laboratory procedures and it is expensive. Here, we report a retrospective study of quantitative fluorescent polymerase chain reaction (QF-PCR) for prenatal detection of trisomies 13, 18 and 21. METHODS: QF-PCR was performed on a total of 447 amniotic fluids blindly analysed without any knowledge of the cytogenetic results and 43 samples with known karyotype. All samples were tested with at least 4 small tandem repeat markers specific for each chromosome 13, 18 or 21. RESULTS: QF-PCR results on amniotic fluid were consistent with conventional cytogenetic data. QF-PCR detected 5 cases of trisomy 21, 2 cases of trisomy 18, 1 case of trisomy 13 and 1 case with Klinefelter's syndrome. CONCLUSIONS: QF-PCR has proved to be very useful in clinical settings, since it allows the detection of major numerical disorders in a few hours after sampling and thus reduces parental anxiety.
Subject(s)
Down Syndrome/diagnosis , Down Syndrome/genetics , In Situ Hybridization, Fluorescence , Polymerase Chain Reaction/methods , Prenatal Diagnosis/methods , Aneuploidy , Female , Humans , PregnancyABSTRACT
We describe a female infant with severe abnormal phenotype with a de novo partial duplication of the short arm of the X chromosome. Chromosome painting confirmed the origin of this X duplication. Molecular cytogenetic analysis with fluorescence in situ hybridization (FISH) was performed with YAC probes, further delineating the breakpoints. The karyotype was 46, X dup(X)(p11-p21.2). Cytogenetic replication studies showed that the normal and duplicated X chromosomes were randomly inactivated in lymphocytes. In most females with structurally abnormal X chromosomes, the abnormal chromosome is inactivated and they are phenotypically apparently normal relatives of phenotypically abnormal males having dupX. Therefore, in this case, there is functional disomy of Xp11-p21.2 in the cells with an active dup(X), most likely resulting in abnormal clinical findings in the patient.
Subject(s)
Cytogenetic Analysis/methods , Dosage Compensation, Genetic , Gene Duplication , Pregnancy Complications , Sex Chromosome Aberrations/genetics , X Chromosome/genetics , Adult , Female , Humans , In Situ Hybridization, Fluorescence , Infant, Newborn , Male , Middle Aged , Phenotype , PregnancyABSTRACT
We report on a 22 year old man with hyperpigmentation distributed along the lines of Blaschko in whom cytogenetic analysis showed mosaicism for an unusual supernumerary marker chromosome. The patient was of normal intelligence and was not dysmorphic. The marker was present in 30% of his lymphocytes and in 6% of his skin fibroblasts from a dark area, while fibroblasts from a light area showed a normal karyotype, 46,XY. We have identified the origin of the marker using fluorescence in situ hybridisation (FISH) with whole chromosome painting probes and YAC specific clones. The marker was found to consist of duplicated chromosome material from the distal part of chromosome 3q and was interpreted as inv dup(3)(qter-->q27.1::q27.1-->qter). Hence, this marker did not include any known centromeric region and no alpha satellite DNA could be detected at the site of the primary constriction. The patient was therefore tetrasomic for 3q27-q29 in the cells containing the marker chromosome. We postulate that, in our case, pigmentary anomalies may result directly from the gain of specific pigmentation genes localised on chromosome 3q.
