[Value of molecular cytogenetics in pre- and postnatal diagnostic of chromosome abnormalities].
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Chromosome Aberrations↗
Biomedical subjects
D Sanlaville
Publications and source records attributed to D Sanlaville.
Maternal uniparental heterodisomy of chromosome 14: chromosomal mechanism and clinical follow up.
To our knowledge, 22 cases of chromosome 14 maternal uniparental disomy (UPD(14)mat) have been reported so far. The majority of cases were ascertained because of an abnormal phenotype associated with a Robertsonian translocation involving chromosome 14. We report here on a child with UPD(14)mat detected prenatally and resulting from trisomy rescue in a maternal meiosis I non-disjunction trisomic zygote. After four years of clinical follow up, in addition to intrauterine growth retardation (IUGR), only short stature and small hands and feet were observed. These clinical data as well as the ascertainment and mechanism of origin of UPD(14)mat were compared with those observed in previously reported cases. It appears that the clinical spectrum of UPD(14)mat is milder in our patient than in patients with UPD(14)mat resulting from other chromosomal mechanisms. In addition, a hypothesis based on abnormal imprinting is proposed to explain the variability of the UPD(14)mat.
Adult↗
De novo inverted duplication 9p21pter involving telomeric repeated sequences.
We report on clinical and cytogenetic findings in a boy with partial 9p duplication, dup(9)(p21pter). Clinical manifestations included facial and hand anomalies and mental retardation. Fluorescence in situ hybridization (FISH) and comparative genomic hybridization (CGH) were used to characterize further and confirm the conventional banding data. Investigation by FISH using whole chromosome 9 paint probe showed that the additional material was derived from chromosome 9. Using CGH, a region of gain was found in the chromosome segment 9p21pter. YACs and telomeric probes confirmed the duplicated region. Using the all-human telomeric sequences probe, intrachromosomal telomeric signal was noted on the short arm of the abnormal chromosome 9. Mechanism of formation of the duplication, including intrachromosomal telomeric sequences, is discussed.
Abnormalities, Multiple↗
[Spectral karyotyping (SKY) principle, avantages and limitations].
Banding karyotype is a routine technique, which allows the identification of numerous aneusomy and/or aneuploïdy in congenital diseases and cancers. However, this analysis fails to detect small or complex chromosome rearrangements. Molecular cytogenetic techniques like fluorescence in situ hybridization (FISH) analysis can overlap these limitations. Particularly, multicolor karyotyping by spectral karyotyping (SKY) may rectify or precise the conventional karyotype results. With two examples, we present here, the principle, the indications and the limits of this technique for constitutional and cancer chromosomal abnormalities characterization. Moreover, we present an easy way to build efficient sky probes with a best sensitivity than the probes classically used.
Adult↗
[A preliminary study to assess the value of the DNA chips SpectralChip to detect subtle constitutional chromosome imbalances].
Comparative genomic hybridization on a microarray (microarray-CGH) allows to detect genomic chromosome imbalances. In order to assess its value to detect small chromosome imbalances observed in a clinical setting, using a DNA chip available commercially (Spectral Genomics, Houston, Texas, USA), we studied the DNA of 9 patients carrying a well characterized chromosome imbalance and the DNA of 11 patients where cytogenetic techniques such as high resolution banding karyotype, FISH using subtelomeric probes and comparative genomic hybridization on metaphase chromosomes conclude to a normal and/or balanced karyotype. A result was obtained for 19/20 patients. Failure of hybridization was observed for one patient. For all the other cases the sex of patients was correctly identified. Microarray-CGH was able to correctly diagnose the chromosome imbalance in 6/8 patients carrying such a defect i.e 9/11 imbalances (deletion or duplication) were detected. No chromosome imbalance was observed in 11 patients considered normal and/or balanced using cytogenetic techniques. Several clones were found to be polymorphic and required FISH studies to eliminate duplication or deletion. In conclusion, we think that this commercially available DNA chip might be useful to screen for chromosome imbalances. However, technical improvements are still necessary before using it in a clinical setting. Also, further studies are necessary to assess its sensitivity and specificity.
Chromosome Aberrations↗