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Objective We surveyed the datasheets of 29 laboratories concerning prenatal diagnosis of de novo apparently balanced chromosome rearrangements to assess the involvement of specific chromosomes, the breakpoints distribution and the impact on the pregnancy outcome.Method By means of a questionnaire, data on 269.371 analyses performed from 1983 to 2006 on amniotic fluid, chorionic villus and fetal blood samples were collected.Results A total of 246 balanced anomalies were detected at frequencies of 72% for reciprocal translocations, 18% for Robertsonian translocations, 7% for inversions and 3% for complex chromosome rearrangements. The total frequencies of balanced rearrangements were 0.09%, 0.08% and 0.05% on amniotic fluid, chorionic villus and fetal blood samples.Conclusion A preferential involvement of chromosomes 22, 7, 21, 3, 9 and 11 and a less involvement of chromosomes X, 19, 12, 6 and 1 was observed. A nonrandom distribution of the breakpoints across chromosomes was noticed. Association in the location of recurrent breakpoints and fragile sites was observed for chromosomes 11, 7, 10 and 22, while it was not recorded for chromosome 3. The rate of pregnancy termination was about 20%, with frequencies decreasing from complex chromosomal rearrangements (33%), reciprocal translocations (24%) to inversions (11%) and Robertsonian translocations (3%).

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It is known that the bone marrow (BM) CD133(+) cells play an important role in the hematopoietic compartment, but this is not their only role. The cells indeed can take part in vascular reconstitution when they become endothelial cells (EC), in skeletal muscle fiber regeneration when there is a switch in muscle precursors, and to cardiomyocyte phenotypic conversion when differentiating in cardiomyocytes-like cells. While the role in hematopoiesis and vasculogenesis of the selected cells is well established, their ability to differentiate along multiple non-EC lineages has not yet been fully elucidated. The goal of this study is to assert whether human CD133(+)BM-derived cells are able to differentiate in vitro, besides to blood cells, cell lineages pertinent to the mesoderm germ layers. To this end, we isolated CD133(+) cells using a clinically approved methodology and compared their differentiation potential to that of hematopoietic progenitor cells (HPCs) and mesenchymal stem cells (MSCs) obtained from the same BM samples. In our culture conditions, CD133 expression was consistently decreased after passage 2, as well as the expression of the stemness markers c-kit and OCT4, whereas expression of Stage Specific Embryonic Antigen 4 (SSEA4) remained consistent in all different conditions. Expanded CD133 were also positive for HLA-ABC, but negative for HLA-DR, in accordance with what has been previously reported for MSCs. Moreover, CD133(+) cells from human BM demonstrated a wide range of differentiation potential, encompassing not only mesodermal but also ectodermal (neurogenic) cell lineages. CD133 antigen could be potentially used to select a cell population with similar characteristics as MSCs for therapeutic applications.

Purpose: We evaluated the experiences of 19 Italian laboratories concerning 241 small supernumerary marker chromosomes (sSMCs) with the aim of answering questions arising from their origin from any chromosome, their variable size and genetic content, and their impact on the carrier's phenotype. Methods: Conventional protocols were used to set up the cultures and chromosome preparations. Both commercial and homemade probes were used for the fluorescent in situ hybridization analyses. Results: A total of 113 of the 241 sSMCs were detected antenatally, and 128 were detected postnatally. There were 52 inherited and 172 de novo cases. Abnormal phenotype was present in 137 cases (57%), 38 of which were antenatally diagnosed. A mosaic condition was observed in 87 cases (36%). In terms of morphology, monocentric and dicentric bisatellited marker chromosomes were the most common, followed by monocentric rings and short-arm isochromosomes. The chromosomes generating the sSMCs were acrocentric in 132 cases (69%) and non-acrocentric chromosomes in 60 cases (31%); a neocentromere was hypothesized in three cases involving chromosomes 6, 8, and 15. The widespread use of molecular cytogenetic techniques in diagnostic laboratories has improved diagnostic quality, especially in prenatal cases. However, one of the few major problems remaining is the identification of the nature and origin of small supernumerary marker chromosomes (sSMCs).sSMCs display a wide range of morphology and occur at highly variable incidence, 1,2 thus giving rise to considerable problems in genetic counseling, particularly during prenatal testing. Only the combined use of conventional and molecular