Chromosomal rearrangements of the human MLL (mixed lineage leukemia) gene are associated with high-risk infant, pediatric, adult and therapy-induced acute leukemias. We used long-distance inverse-polymerase chain reaction to characterize the chromosomal rearrangement of individual acute leukemia patients. We present data of the molecular characterization of 1590 MLL-rearranged biopsy samples obtained from acute leukemia patients. The precise localization of genomic breakpoints within the MLL gene and the involved translocation partner genes (TPGs) were determined and novel TPGs identified. All patients were classified according to their gender (852 females and 745 males), age at diagnosis (558 infant, 416 pediatric and 616 adult leukemia patients) and other clinical criteria. Combined data of our study and recently published data revealed a total of 121 different MLL rearrangements, of which 79 TPGs are now characterized at the molecular level. However, only seven rearrangements seem to be predominantly associated with illegitimate recombinations of the MLL gene (∼90%): AFF1/AF4, MLLT3/AF9, MLLT1/ENL, MLLT10/AF10, ELL, partial tandem duplications (MLL PTDs) and MLLT4/AF6, respectively. The MLL breakpoint distributions for all clinical relevant subtypes (gender, disease type, age at diagnosis, reciprocal, complex and therapy-induced translocations) are presented. Finally, we present the extending network of reciprocal MLL fusions deriving from complex rearrangements.

Holoprosencephaly (HPE) is a complex brain malformation resulting from incomplete cleavage of the prosencephalon, occurring between the 18th and the 28th day of gestation and affecting both the forebrain and the face. It is estimated to occur in 1/16,000 live births and 1/250 conceptuses. Three ranges of increasing severity are described: lobar, semi-lobar and alobar HPE. Another milder subtype of HPE called middle interhemispheric variant (MIHF) or syntelencephaly is also reported. In most of the cases, facial anomalies are observed in HPE, like cyclopia, proboscis, median or bilateral cleft lip/palate in severe forms, ocular hypotelorism or solitary median maxillary central incisor in minor forms. These latter midline defects can occur without the cerebral malformations and then are called microforms. Children with HPE have many medical problems: developmental delay and feeding difficulties, epilepsy, instability of temperature, heart rate and respiration. Endocrine disorders like diabetes insipidus, adrenal hypoplasia, hypogonadism, thyroid hypoplasia and growth hormone deficiency are frequent. To date, seven genes have been positively implicated in HPE: Sonic hedgehog (SHH), ZIC2, SIX3, TGIF, PTCH, GLI2 and TDGF1. A molecular diagnosis can be performed by gene sequencing and allele quantification for the four main genes SHH, ZIC2, SIX3 and TGIF. Major rearrangements of the subtelomeres can also be identified by multiplex ligation-dependent probe amplification (MLPA). Nevertheless, in about 70% of cases, the molecular basis of the disease remains unknown, suggesting the existence of several other candidate genes or environmental factors. Consequently, a "multiple-hit hypothesis" of genetic and/ or environmental factors (like maternal diabetes) has been proposed to account for the extreme clinical variability. In a practical approach, prenatal diagnosis is based on ultrasound and magnetic resonance imaging (MRI) rather than on molecular diagnosis. Treatment is symptomatic and supportive, and requires a multidisciplinary management. Child outcome depends on the HPE severity and the medical and neurological complications associated. Severely affected children have a very poor prognosis. Mildly affected children may exhibit few symptoms and may live a normal life.

IntroductionMesenchymal stromal cells (MSCs) are multipotent stem cells able to differentiate into mesoderm-derived cells, 1 and exhibit immunoregulatory properties. 2 MSCs have been used in the context of allogeneic hematopoietic stem cell transplantation to improve hematopoietic engraftment, to prevent graft failure, and to reduce the incidence or severity of acute graft-versus-host disease (GVHD). [3][4][5] MSCs obtained from bone marrow (BM) can undergo in vitro expansion in medium containing either fetal calf serum (FCS), with or without fibroblast growth factor (FGF-2), or platelet lysate (PL). 6 However, little is known about the effect of donor selection or culture conditions on the functional properties and therapeutic potential of clinical-grade MSCs.Recent studies have suggested that MSCs can contribute to tumor growth and metastasis. 7 A related concern is the capacity of MSCs for oncogenic transformation. Mouse MSCs show chromosomal abnormalities and are highly susceptible to transformation associated with an increased telomerase activity and myc expression, and a loss of p53 and p16. [8][9][10] In contrast, human MSCs are more resistant to transformation in vitro with no genomic instability detected and no tumor induced after long-term in vivo transfer. [11][12][13][14][15] After 20 to 50 population doublings (PDs), human MSCs undergo replicative senescence, with telomere shortening and increased p16 expression. 16 They require the same steps to achieve transformation as for differentiated cells, suggesting that they are not prone to spontaneous transformation. 17 Nevertheless, one recent study described the transformation of human adipose tissue-derived MSCs with up-regulation of myc, repression of p16, acquisition of telomerase activity, 18 and generation of carcinoma in mice. 19 We investigated the immune properties and resistance to transformation of MSCs produced in 4 cell therapy facilities during 2 multicenter clinical trials designed to evaluate the capacity of BM-MSCs to prevent acute GVHD or to treat irradiationinduced lesions. MethodsDetails regarding methods are provided in the supplemental data (available on the Blood website; see the Supplemental Materials link at the top of the online article). For personal use only. on March 28, 2019. by guest www.bloodjournal.org From (1A to 11A) were done for the GVHD prevention clinical trial, and 4 (12A, 13A2) to treat accidentally irradiated patients. For irradiated patients, 5 supplemental MSC productions (12B to 16B) were done using human PL. 6 MSC production Growth kinetics and MSC characterizationGrowth kinetics was assessed by studying total fold increase, total number of PDs, and colony-forming unit-fibroblast. MSCs were screened for the expression of CD45, CD73, CD105, CD90, and human leukocyte antigen-DR (HLA-DR) and were also checked for their capacity to stimulate the growth of allogeneic peripheral blood mononuclear cells (PBMCs) and to inhibit alloantigen-driven proliferation of PBMCs. Cytogenetic analysisAt the end of the first (P ...

In human carcinomas, especially breast cancer, chromosome arm 8p is frequently involved in complex chromosomal rearrangements that combine amplification at 8p11-12, break in the 8p12-21 region, and loss of 8p21-ter. Several studies have identified putative oncogenes in the 8p11-12 amplicon. However, discrepancies and the lack of knowledge on the structure of this amplification lead us to think that the actual identity of the oncogenes is not definitively established. We present here a comprehensive study combining genomic, expression, and chromosome break analyses of the 8p11-12 region in breast cell lines and primary breast tumors. We show the existence of four amplicons at 8p11-12 using array comparative genomic hybridization. Gene expression analysis of 123 samples using DNA microarrays identified 14 genes significantly overexpressed in relation to amplification. Using fluorescence in situ hybridization analysis on tissue microarrays, we show the existence of a cluster of breakpoints spanning a region just telomeric to and associated with the amplification. Finally, we show that 8p11-12 amplification has a pejorative effect on survival in breast cancer. (Mol Cancer Res 2005;3(12):655 -67)