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Tatton-Brown-Rahman (TBRS) syndrome is a recently described overgrowth syndrome caused by loss of function variants in the DNMT3A gene. This gene encodes for a DNA methyltransferase 3 alpha, which is involved in epigenetic regulation, especially during embryonic development. Somatic variants in DNMT3A have been widely studied in different types of tumors, including acute myeloid leukemia, hematopoietic, and lymphoid cancers. Germline gain-of-function variants in this gene have been recently implicated in microcephalic dwarfism. Common clinical features of patients with TBRS include tall stature, macrocephaly, intellectual disability (ID), and a distinctive facial appearance. Differential diagnosis of TBRS comprises Sotos, Weaver, and Malan Syndromes. The majority of these disorders present other clinical features with a high clinical overlap, making necessary a molecular confirmation of the clinical diagnosis. We here describe seven new patients with variants in DNMT3A, four of them with neuropsychiatric disorders, including schizophrenia and psychotic behavior. In addition, one of the patients has developed a brain tumor in adulthood. This patient has also cerebral atrophy, aggressive behavior, ID, and abnormal facial features. Clinical evaluation of this group of patients should include a complete neuropsychiatric assessment together with psychological support in order to detect and manage abnormal behaviors such as aggressiveness, impulsivity, and attention deficit-hyperactivity disorder. TBRS should be suspected in patients with overgrowth, ID, tall stature, and macrocephaly, who also have some neuropsychiatric disorders without any genetic defects in the commonest overgrowth disorders. Molecular confirmation in these patients is mandatory.

Efficient methodologies for recreating cancer-associated chromosome translocations are in high demand as tools for investigating how such events initiate cancer. The CRISPR/Cas9 system has been used to reconstruct the genetics of these complex rearrangements at native loci while maintaining the architecture and regulatory elements. However, the CRISPR system remains inefficient in human stem cells. Here, we compared three strategies aimed at enhancing the efficiency of the CRISPR-mediated t(11;22) translocation in human stem cells, including mesenchymal and induced pluripotent stem cells: (1) using end-joining DNA processing factors involved in repair mechanisms, or (2) ssODNs to guide the ligation of the double-strand break ends generated by CRISPR/Cas9; and (3) all-in-one plasmid or ribonucleoprotein complex-based approaches. We report that the generation of targeted t(11;22) is significantly increased by using a combination of ribonucleoprotein complexes and ssODNs. The CRISPR/Cas9-mediated generation of targeted t(11;22) in human stem cells opens up new avenues in modeling Ewing sarcoma.

Recently, a consensus International Prognostic Scoring System (IPSS) for predicting outcome and planning therapy in the myelodysplastic syndromes (MDS) has been developed. However, the intermediate-risk cytogenetic subgroup defined by the IPSS includes a miscellaneous number of different single abnormalities for which real prognosis at present is uncertain. The main aims of this study were to evaluate in an independent series the prognostic value of the IPSS and to identify chromosomal abnormalities with a previously unrecognized good or poor prognosis in 640 patients. In univariate analyses, cases with single 1q abnormalities experienced poor survival, whereas those with trisomy 8 had a higher risk of acute leukaemic transformation than the remaining patients (P = 0.004 and P = 0.009 respectively). Patients with single del(12p) had a similar survival to patients with a normal karyotype and showed some trend for a better survival than other cases belonging to the IPSS intermediate-risk cytogenetic subgroup (P = 0.045). Multivariate analyses demonstrated that IPSS cytogenetic prognostic subgroup, proportion of bone marrow blasts and haemoglobin level were the main prognostic factors for survival, and the first two characteristics and platelet count were the best predictors of acute leukaemic transformation risk. A large international co-operative study should be carried out to clarify these findings.

Mutations in BRCA1 and BRCA2 genes confer a high risk of breast and ovarian cancer but the incomplete penetrance of these mutations suggests that other genetic and/or environmental factors may modify this risk. We present a family where all affected members carried a mutation in the BRCA1 gene and the index case had suffered from cancer twice in the last 27 years, whereas her monozygotic twin sister, also a carrier of the mutation, remained healthy. As copy number variants (CNVs) contribute to phenotypic diversity, a comparative genomic hybridization array (CGH) was performed to see whether the differences in the CNV profile were a modifier factor of the phenotype in our monozygotic twins. Our results show that differences in the CNVs profile were not the cause of the extremely variable penetrance observed in our MZ twin. The search for an explanation should not therefore be limited to genetic changes at the level of the DNA sequence.

We report a case of de novo acute myelogenous leukaemia FAB subtype M1 that presents a cytogenetic complex translocation between chromosomes 7, 9 and 22, producing a 'variant' Philadelphia chromosome. Molecular analysis revealed a BCR-ABL rearrangement involving exons b3 and a2 (b3a2). Haematological parameters and genetic analysis again raise the problem of the true nature of this disease, which is briefly discussed.

The nucleoporin 98 gene (NUP98) has been reported to be fused to 13 partner genes in hematological malignancies with 11p15 translocations. Twelve of them have been identified in patients with myeloid neoplasias and only 1, RAP1GDS1 (4q21), is fused with NUP98 in five patients with T-cell acute lymphoblastic leukemia (T-ALL). Three of these patients coexpressed T and myeloid markers, suggesting the specific association of t(4;11)(q21;p15) with a subset of T-ALL originating from an early progenitor, which has the potential to express mature T-cell antigens as well as myeloid markers. We describe here a new NUP98 partner involved in a t(10;11)(q25;p15) in a patient with acute biphenotypic leukemia, showing coexpression of mature T and myeloid markers. The gene involved, located in 10q25, was identified as ADD3 using 3'-RACE. ADD3 codes for the ubiquitous expressed subunit gamma of the adducin protein, and it seems to play an important role in the skeletal organization of the cell membrane. Both NUP98-ADD3 and ADD3-NUP98 fusion transcripts are expressed in the patient. This is the second partner of NUP98 described in T-ALL. Adducin shares with the product of RAP1GDS1, and with all of the nonhomeobox NUP98 partners, the presence of a region with significant probability of adopting a coiled-coil conformation. This region is always retained in the fusion transcript with the NH(2) terminus FG repeats of NUP98, suggesting an important role in the mechanism of leukemogenesis.

Karyotypic information on multiple myeloma (MM) is less extensive than that on other myeloid or lymphoid malignancies due to low mitotic activity of plasma cells. An add(14)(q32) marker chromosome has been reported to be the most frequent recurring abnormality in clonally abnormal cases; in approximately one third of the latter cases, this marker has been identified as a der(14)t(11;14)(q13;q32) chromosome. To map chromosomal breakpoints, characterize the add(14)(q32) marker chromosomes, and to identify other recurring translocations in MM, we used spectral karyotyping (SKY) to analyze a panel of nine bone marrow (BM) biopsy samples from eight patients and 10 tumor cell lines derived from MM patients. SKY involves hybridization of 24 fluorescently labeled chromosome painting probes to metaphase spreads in such a manner that simultaneous visualization of each of the chromosomes in a different color is accomplished. By this method, it was possible to define all chromosomal rearrangements and identify all of the clonal marker chromosomes in tumor cells. By detailed mapping of breakpoints of rearrangement, it was also possible to identify several novel recurring sites of breakage that map to the chromosomal bands 3q27, 17q24-25, and 20q11. The partner chromosomes in translocations that generated the add (14)(q32) marker chromosomes were identified in all cases in which they were detected by G-banding (one biopsy and six cell lines). In addition, two new translocations involving band 14q32, ie, t(12;14)(q24;q32) and t(14;20)(q32;q11) have also been identified. These studies demonstrate the power of SKY in resolving the full spectrum of chromosome abnormalities in tumors.