Cornelia de Lange syndrome with NIPBL mutation and mosaic Turner syndrome in the same individual.

BACKGROUND: Cornelia de Lange syndrome (CdLS) is a dominantly inherited disorder characterized by facial dysmorphism, growth and cognitive impairment, limb malformations and multiple organ involvement. Mutations in NIPBL gene account for about 60% of patients with CdLS. This gene encodes a key regulator of the Cohesin complex, which controls sister chromatid segregation during both mitosis and meiosis. Turner syndrome (TS) results from the partial or complete absence of one of the X chromosomes, usually associated with congenital lymphedema, short stature, and gonadal dysgenesis. CASE PRESENTATION: Here we report a four-year-old female with CdLS due to a frameshift mutation in the NIPBL gene (c.1445_1448delGAGA), who also had a tissue-specific mosaic 45,X/46,XX karyotype. The patient showed a severe form of CdLS with craniofacial dysmorphism, pre- and post-natal growth delay, cardiovascular abnormalities, hirsutism and severe psychomotor retardation with behavioural problems. She also presented with minor clinical features consistent with TS, including peripheral lymphedema and webbed neck. The NIPBL mutation was present in the two tissues analysed from different embryonic origins (peripheral blood lymphocytes and oral mucosa epithelial cells). However, the percentage of cells with monosomy X was low and variable in tissues. These findings indicate that, ontogenically, the NIPBL mutation may have appeared before the mosaic monosomy X. CONCLUSIONS: The coexistence in several patients of these two rare disorders raises the issue of whether there is indeed a cause-effect association. The detailed clinical descriptions indicate predominant CdLS phenotype, although additional TS manifestations may appear in adolescence.

Microarray testing as an efficient tool to redefine hyperdiploid paediatric B-cell precursor acute lymphoblastic leukaemia patients.

The aim of our study was to characterize genetic alterations in a cohort of paediatric patients with B-cell progenitors (BCP-ALL) and a hyperdiploid karyotype. In our study, we analysed 55 childhood hyperdiploid BCP-ALL patients using single nucleotide polymorphism (SNP) microarray testing. The group consisted mostly of patients with the modal number of chromosomes between 54 and 58 (34 cases). Within this group, Trisomy 4 and Trisomy 10 (30 cases) were the most frequent cases. Additionally, a total of 93 structural abnormalities mainly affecting chromosomes 1, 6, 9, 12, and 17 as well as 68 copy number alterations (CNAs) were identified. The microarray testing revealed a loss of ETV6, IKZF1, CDKN2A/CDKN2B, PAX5, and RB1. Moreover, chromosomal abnormalities resulting in the loss of heterozygosity (LOH) were also observed. Currently, patients with hyperdiploidy constitute a genetically heterogeneous group, and therefore, it is insufficient to rely only on banding cytogenetic analysis for the identification of hyperdiploid karyotype. Microarray testing has been proven an effective and satisfactory tool for the analysis of molecular karyotypes and to redefine the prognostic criteria in hyperdiploid patients.

The effectiveness of high-resolution-comparative genomic hybridization in detecting the most common chromosomal abnormalities in pediatric myelodysplastic syndromes.

Myelodysplastic syndromes (MDS) are a diverse and heterogeneous group of clonal and potentially malignant bone marrow (BM) disorders. The up-to-date used criteria are the ones proposed by the French-American-British (FAB) group in 1982, the World Health Organization (WHO) classification, and a new, recently presented classification: categories cytology cytogenetics (CCC) system or 2003 WHO classification scheme. Comparative genomic hybridization (CGH) is a technique that permits the detection of chromosomal imbalances within a "one step" analysis. In our study, we present 5 cases of MDS and 4 cases of acute myelogenous leukemia (AML). By means of high-resolution CGH (HR-CGH) analysis, we were able to detect DNA copy number alterations in 8 out of 9 samples. The changes were as follows: -7, -Y, del(5)(q33q34), del(11)(q22q24), del(5p), del(9)(q21q31), nullisomy X, and +8. In 5/9 cases the HR-CGH data were highly comparable with conventional cytogenetics and interphase/metaphase fluorescence in situ hybridization findings. Additionally, in 3 BM samples the HR-CGH revealed the presence of changes that had not been detected by conventional cytogenetics: del(5p), del(5)(q33q34), del(9)(q21q31), and nullisomy X. The high effectiveness, specificity, and sensitivity of this method are in concordance with the conventional cytogenetics and FISH findings and the ability to detect new changes.

Fluorescence in situ hybridization BCR/ABL fusion signal rate in interphase nuclei of healthy volunteer donors: a test study for establishing false positive rate.

Fluorescence in situ hybridization (FISH) using chromosome-specific DNA probes is rapidly becoming a part of clinical laboratory practice. However, as a relatively new clinical test, it is not yet standardized and for practical reasons each laboratory must establish its own criteria. For this purpose we have evaluated the specificity of a dual-color BCR/ABL translocation probe by establishing the range of BCR/ABL fusion-positive scores in a healthy donor group. The false positive rate (FPR), determined by the percent of FISH BCR/ABL fusion-positive cells found in the specimens of healthy donors, was estimated at 2.3% (mean = 1%-4%). Thus the cut-off value for false positive nuclei was set at 5%.

Structural and numerical abnormalities resolved in one-step analysis: the most common chromosomal rearrangements detected by comparative genomic hybridization in childhood acute lymphoblastic leukemia.

Comparative genomic hybridization (CGH) is a technique that permits detection of chromosomal imbalances. This method allows the detection of gains and losses of genetic material at a resolution lower than 5 Mb. The limitations of conventional cytogenetic studies, such as morphologically insufficient quality of metaphases or the mitotic index, can be eliminated by use of CGH. It is particularly important in the diagnosis of leukemias, and CGH could be a useful tool enabling more precise cytogenetic analysis of leukemic cells. A group of 89 children with acute lymphoblastic leukemia was studied by means of CGH using bone marrow obtained from all consecutive pediatric patients. CGH experiments were performed according to the manufacturer's instruction with minor modifications. In addition, each sample was examined with standard GTG technique and fluorescence in situ hybridization. The conventional cytogenetics failed in 12 patients (13.5%), and 22 patients (24.7%) had a normal karyotype. Structural and numerical changes were found in 55 cases (61.8%) displaying a different abnormalities including deletions, trisomies, tetrasomies, isochromosomes, and markers with unknown origin. However, all samples were successfully analyzed by CGH. We have shown that high-resolution comparative genomic hybridization analysis is a reliable and relatively quick one-step method to identify main aberrations that would not be detected by either conventional G banding or by conventional fluorescence in situ hybridization. It should be considered to establish CGH as a routine analysis for screening patients with acute lymphoblastic leukemia.