Craniofrontonasal syndrome in a male due to chromosomal mosaicism involving EFNB1: further insights into a genetic paradox.

Craniofrontonasal syndrome (CFNS) is an X-linked disorder caused by inactivating mutations in the gene for ephrin-B1 (EFNB1). Paradoxically it shows a more severe phenotype in females than in males. As a result of X inactivation cell populations with and without EFNB1 expression are found in EFNB1+/- females. This is thought to initiate a process termed cellular interference which may be responsible for the phenotype in females. We present a boy with severe clinical features of CFNS. In ∼42% of his blood cells we found a supernumerary ring X chromosome containing EFNB1 but lacking XIST. Mosaicism for cell populations with different levels of EFNB1 expression can explain the severe phenotype of this patient. In vitro experiments in Xenopus tissue showed that cells overexpress ephrinB1 cluster and sort out from wild-type cells. Our report provides further evidence that cellular interference contributes to the paradoxical inheritance pattern of CFNS.

Silver-Russell syndrome due to maternal uniparental disomy 7 and a familial reciprocal translocation t(7;13).

Silver-Russell syndrome (SRS) is a genetically heterogeneous disorder characterized by intrauterine and postnatal growth retardation, typical facial features and a spectrum of additional features including body and limb asymmetry and clinodactyly. Maternal uniparental disomy for chromosome 7 (upd(7)mat) was shown to occur in 5-10% of patients with SRS. Maternal UPD7 is clinically often associated with mild SRS. Parents of an affected child are given a negligible recurrence risk as all reported cases with upd(7)mat have been sporadic so far. In general, chromosomal rearrangements-like translocations increase the likelihood of uniparental disomy (UPD) for the chromosomes involved. However, SRS as the result of a upd(7)mat in association with an inherited chromosomal translocation involving chromosome 7 has only been reported once before. Here, we describe the second case of SRS with upd(7)mat due to a familial reciprocal translocation t(7;13). This emphasizes the importance of chromosome analysis in SRS patients with upd(7)mat to rule out chromosomal rearrangements despite their rare occurrence as they are of great relevance for genetic counseling of SRS families.

[A patient with fever of unknown origin - a common cause with an atypical presentation]. / Der Fall eines Patienten mit Fieber unklarer Genese - eine bekannte Ursache mit atypischer Präsentation.

Fever of unknown origin (FUO) is a common medical diagnosis by exclusion. In these cases, fever is the predominant symptom of an underlying disease. We describe the case of a 60-year old patient with FUO. Intensive search for the causative disease was carried out. Unfortunately all the investigations remained fruitless. Eventually, the patient was discharged with the diagnosis of common variable immunodeficiency, based on hypogammaglobulinemia and Cytomegalovirus replication. Two weeks after discharge, the patient presented in the outpatient clinic with the typical symptoms of giant cell arteriitis (GCA). The diagnosis was confirmed by a repeated ultrasound imaging and biopsy findings. The clinical condition of the patient improved rapidly after beginning of treatment with steroids. This case illustrates the importance of a longitudinal observation of patients presenting with FUO if the diagnosis remains unclear after intensive investigations.

Pseudoautosomal inheritance of Léri-Weill syndrome: what does it mean?

The short stature homeobox (SHOX) gene is located in the pseudoautosomal region 1 of both sex chromosomes. Haploinsufficiency of SHOX leads to different phenotypes ranging from isolated short stature to Léri-Weill syndrome characterized by short stature, mesomelia and Madelung deformity. We describe a family with a SHOX deletion originally located on the Y chromosome and transmitted from father to daughter by crossover during meiosis. The male index patient presented with short stature, mesomelia and mild Madelung deformity. His father had a normal height but slightly disproportionate short legs. The sister of the index patient presented with marked Madelung deformity and normal height. A deletion of the SHOX gene was identified in the male index patient, his father and his sister. Metaphase fluorescence in situ hybridization (FISH) analyses showed a deletion of the SHOX gene on the Y chromosomes of the index patient and his father, and on the X chromosome of his sister, indicating that a meiotic crossover of the SHOX gene region between the X and Y chromosomes had occurred. The pseudoautosomal region 1 is a known recombination 'hot spot' in male meiosis. Published genetic maps indicate high recombination frequency of ∼40% for SHOX in male meiosis leading to pseudoautosomal inheritance.

Frequent loss of chromosome 9, homozygous CDKN2A/p14(ARF)/CDKN2B deletion and low TSC1 mRNA expression in pleomorphic xanthoastrocytomas.

The molecular pathogenesis of pleomorphic xanthoastrocytoma (PXA), a rare astrocytic brain tumor with a relatively favorable prognosis, is still poorly understood. We characterized 50 PXAs by comparative genomic hybridization (CGH) and found the most common imbalance to be loss on chromosome 9 in 50% of tumors. Other recurrent losses affected chromosomes 17 (10%), 8, 18, 22 (4% each). Recurrent gains were identified on chromosomes X (16%), 7, 9q, 20 (8% each), 4, 5, 19 (4% each). Two tumors demonstrated amplifications mapping to 2p23-p25, 4p15, 12q13, 12q21, 21q21 and 21q22. Analysis of 10 PXAs with available high molecular weight DNA by high-resolution array-based CGH indicated homozygous 9p21.3 deletions involving the CDKN2A/p14(ARF)/CDKN2B loci in six tumors (60%). Interphase fluorescence in situ hybridization to tissue sections confirmed the presence of tumor cells with homozygous 9p21.3 deletions. Mutational analysis of candidate genes on 9q, PTCH and TSC1, revealed no mutations in PXAs with 9q loss and no evidence of TSC1 promoter methylation. However, PXAs consistently showed low TSC1 transcript levels. Taken together, our study identifies loss of chromosome 9 as the most common chromosomal imbalance in PXAs and suggests important roles for homozygous CDKN2A/p14(ARF)/CDKN2B deletion as well as low TSC1 mRNA expression in these tumors.

Bortezomib before and after high-dose therapy in myeloma: long-term results from the phase III HOVON-65/GMMG-HD4 trial.

The Dutch-Belgian Cooperative Trial Group for Hematology Oncology Group-65/German-speaking Myeloma Multicenter Group-HD4 (HOVON-65/GMMG-HD4) phase III trial compared bortezomib (BTZ) before and after high-dose melphalan and autologous stem cell transplantation (HDM, PAD arm) compared with classical cytotoxic agents prior and thalidomide after HDM (VAD arm) in multiple myeloma (MM) patients aged 18-65 years. Here, the long-term follow-up and data on second primary malignancies (SPM) are presented. After a median follow-up of 96 months, progression-free survival (censored at allogeneic transplantation, PFS) remained significantly prolonged in the PAD versus VAD arm (hazard ratio (HR)=0.76, 95% confidence interval (95% CI) of 0.65-0.89, P=0.001). Overall survival (OS) was similar in the PAD versus VAD arm (HR=0.89, 95% CI: 0.74-1.08, P=0.24). The incidence of SPM were similar between the two arms (7% each, P=0.73). The negative prognostic effects of the cytogenetic aberration deletion 17p13 (clone size ⩾10%) and renal impairment at baseline (serum creatinine >2 mg dl-1) on PFS and OS remained abrogated in the PAD but not VAD arm. OS from first relapse/progression was similar between the study arms (HR=1.02, P=0.85). In conclusion, the survival benefit with BTZ induction/maintenance compared with classical cytotoxic agents and thalidomide maintenance is maintained without an increased risk of SPM.

Lack of CD56 expression on myeloma cells is not a marker for poor prognosis in patients treated by high-dose chemotherapy and is associated with translocation t(11;14).

Lack of CD56 expression was reported to be associated with a poor prognosis in multiple myeloma (MM) patients treated with conventional chemotherapy. Aim of our retrospective study was to analyse whether CD56 expression on MM cells reveals as a prognostic factor in patients treated with high-dose chemotherapy. MM cells of 99 patients prior to treatment with high-dose chemotherapy were analysed for CD56 expression by flow cytometry. Multivariable analysis of event-free survival in these patients showed no statistically significant difference between the CD56(-) (n=28) and the CD56(+) (n=71) group. The lack of CD56 expression on MM cells of these patients correlated significantly with the presence of translocation (11;14) (t(11;14)) (estimated correlation coefficient=0.655 95%, confidence interval (0.481; 0.779)). In summary, our results indicate that lack of CD56 expression on MM cells is not a prognostic marker in patients treated with high-dose chemotherapy, but is associated with t(11;14).

Genome-wide association study of immunoglobulin light chain amyloidosis in three patient cohorts: comparison with myeloma.

Immunoglobulin light chain (AL) amyloidosis is characterized by tissue deposition of amyloid fibers derived from immunoglobulin light chain. AL amyloidosis and multiple myeloma (MM) originate from monoclonal gammopathy of undetermined significance. We wanted to characterize germline susceptibility to AL amyloidosis using a genome-wide association study (GWAS) on 1229 AL amyloidosis patients from Germany, UK and Italy, and 7526 healthy local controls. For comparison with MM, recent GWAS data on 3790 cases were used. For AL amyloidosis, single nucleotide polymorphisms (SNPs) at 10 loci showed evidence of an association at P<10-5 with homogeneity of results from the 3 sample sets; some of these were previously documented to influence MM risk, including the SNP at the IRF4 binding site. In AL amyloidosis, rs9344 at the splice site of cyclin D1, promoting translocation (11;14), reached the highest significance, P=7.80 × 10-11; the SNP was only marginally significant in MM. SNP rs79419269 close to gene SMARCD3 involved in chromatin remodeling was also significant (P=5.2 × 10-8). These data provide evidence for common genetic susceptibility to AL amyloidosis and MM. Cyclin D1 is a more prominent driver in AL amyloidosis than in MM, but the links to aggregation of light chains need to be demonstrated.

Genomic profiling of Acute lymphoblastic leukemia in ataxia telangiectasia patients reveals tight link between ATM mutations and chromothripsis.

Recent developments in sequencing technologies led to the discovery of a novel form of genomic instability, termed chromothripsis. This catastrophic genomic event, involved in tumorigenesis, is characterized by tens to hundreds of simultaneously acquired locally clustered rearrangements on one chromosome. We hypothesized that leukemias developing in individuals with Ataxia Telangiectasia, who are born with two mutated copies of the ATM gene, an essential guardian of genome stability, would show a higher prevalence of chromothripsis due to the associated defect in DNA double-strand break repair. Using whole-genome sequencing, fluorescence in situ hybridization and RNA sequencing, we characterized the genomic landscape of Acute Lymphoblastic Leukemia (ALL) arising in patients with Ataxia Telangiectasia. We detected a high frequency of chromothriptic events in these tumors, specifically on acrocentric chromosomes, as compared with tumors from individuals with other types of DNA repair syndromes (27 cases total, 10 with Ataxia Telangiectasia). Our data suggest that the genomic landscape of Ataxia Telangiectasia ALL is clearly distinct from that of sporadic ALL. Mechanistically, short telomeres and compromised DNA damage response in cells of Ataxia Telangiectasia patients may be linked with frequent chromothripsis. Furthermore, we show that ATM loss is associated with increased chromothripsis prevalence in additional tumor entities.

Synergistic activity of imatinib and 17-AAG in imatinib-resistant CML cells overexpressing BCR-ABL--Inhibition of P-glycoprotein function by 17-AAG.

Overexpression of BCR-ABL and P-glycoprotein (Pgp) are two of the known mechanisms of imatinib resistance. As combination therapy may allow to overcome drug resistance, we investigated the effect of combination treatment with imatinib and 17-allylamino-17-demethoxygeldanamycin (17-AAG), a heat-shock protein 90 (Hsp90) inhibitor, on different imatinib-sensitive and imatinib-resistant CML cell lines. In imatinib-sensitive cells, combination index (CI) values obtained using the method of Chou and Talalay indicated additive (CI=1) or marginally antagonistic (CI>1) effects following simultaneous treatment with imatinib and 17-AAG. In imatinib-resistant cells both drugs acted synergistically (CI<1). In primary chronic-phase CML cells additive or synergistic effects of the combination of imatinib plus 17-AAG were discernible. Annexin V/propidium iodide staining showed that the activity of imatinib plus 17-AAG is mediated by apoptosis. Combination treatment with imatinib plus 17-AAG was more effective in reducing the BCR-ABL protein level than 17-AAG alone. Monotherapy with 17-AAG decreased P-glycoprotein activity, which may increase intracellular imatinib levels and contribute to the sensitization of CML cells to imatinib. The results suggest that combination of imatinib and 17-AAG may be useful to overcome imatinib resistance in a clinical setting.

A novel type of RET rearrangement (PTC8) in childhood papillary thyroid carcinomas and characterization of the involved gene (RFG8).

As part of ongoing studies on the RET rearrangement frequency in children with papillary thyroid carcinoma (PTC) after their exposure to radioactive iodine after the Chernobyl reactor accident, new methods for the detection of novel types of RET rearrangements are being developed. In this study, an improved reverse transcription-PCR strategy is used successfully to identify a new type of RET rearrangement. This rearrangement is designated PTC8 and the involved RET-fused gene (RFG) as RFG8. The identification of two reciprocal transcripts coding for the RFG8/RET and RET/RFG8 fusions suggests that the PTC8 rearrangement results from a balanced chromosomal translocation. With a view to clarify its role in tumor induction, we compared the fusion products with those of previously described RET rearrangements. We therefore sequenced and characterized the RFG8 cDNA, which showed no significant similarity to any functional protein described as yet. RFG8 is located on chromosome 18q21-22 and is expressed ubiquitously. Bioinformatic analysis predicts with a high probability that the corresponding rfg8 protein is located in the cytoplasm and is involved putatively in intracellular transport processes. Furthermore, we identified coiled-coil structures upstream of the breakpoint with one of the coiled-coils showing dimerization capability. Thus the rfg8/ret fusion protein exhibits structures for oncogenic activation that are similar to those observed in previously described RET fusions.

Comparison of DNA gains and losses in primary renal clear cell carcinomas and metastatic sites: importance of 1q and 3p copy number changes in metastatic events.

Archival material from primary and metastatic renal clear cell carcinomas of 25 patients was studied by comparative genomic hybridization. Copy number changes of entire chromosomes or chromosomal subregions were detected in 22 primary and 21 metastatic tumors. Copy number changes affected the following chromosomes in at least 20% of the 25 primary tumors (minimal common region given in parentheses): gains were noted for chromosomes 1 (1q21-->q23), 5 (5q31-->q34), 7 (7p), 8 (8q), 16 (16p), 17 (17q12-->qter), 19, and 22 (22q12-->qter); losses were revealed for chromosomes 3 (3p21-->pter), 8 (8p23-->pter), 14(14q21-->qter), and Y. The same chromosomal regions that were involved in primary renal clear cell carcinomas were also found in the respective metastatic tumors but with strikingly different frequencies for a few regions. Metastatic tumors showed a significantly higher frequency of complete or partial gains of the long arm of chromosome 1, in particular at 1q21-->q23 than primary tumors (16 cases versus 6 cases; P < 0.005). These data suggest a correlation of metastatic events in renal clear cell carcinomas with an increase in the copy number of genes located at 1q, in particular at 1q21-->q23. In contrast, the entire or partial loss of the short arm of chromosome 3 was significantly less frequent in metastatic tumors (8 cases versus 15 cases; P < 0.025). The validity of 1q and 3p copy number changes detected by comparative genomic hybridization was confirmed by interphase cytogenetics with region-specific yeast artificial chromosomes to paraffin-embedded tumor tissue sections.

Chromosomal gains and losses in uveal melanomas detected by comparative genomic hybridization.

Eleven uveal melanomas were analyzed using comparative genomic hybridization (CGH). The most abundant genetic changes were loss of chromosome 3, overrepresentation of 6p, loss of 6q, and multiplication of 8q. The smallest overrepresented regions on 6p and 8q were 6pter-->p21 and 8q24-->qter, respectively. Several additional gains and losses of chromosome segments were repeatedly observed, the most frequent one being loss of 9p (three cases). Monosomy 3 appeared to be a marker for ciliary body involvement. CGH data were compared with the results of chromosome banding. Some alterations, e.g., gains of 6p and losses of 6q, were observed with higher frequencies after CGH, while others, e.g., 9p deletions, were detected only by CGH. The data suggest some similarities of cytogenetic alterations between cutaneous and uveal melanoma. In particular, the 9p deletions are of interest due to recent reports about the location of a putative tumor-suppressor gene for cutaneous malignant melanoma in this region.

Alternative lengthening of telomeres is associated with chromosomal instability in osteosarcomas.

Telomere maintenance is regarded as a key mechanism in overcoming cellular senescence in tumor cells and in most cases is achieved by the activation of telomerase. However there is at least one alternative mechanism of telomere lengthening (ALT) which is characterized by heterogeneous and elongated telomeres in the absence of telomerase activity (TA). We evaluated the prevalence of TA, gene expression of telomerase subunits and ALT in relation to telomere morphology and function in matrix producing bone tumors and in osteosarcoma cell lines and present evidence of a direct association of ALT with telomere dysfunction and chromosomal instability. Telomere fluorescence in situ hybridization (T-FISH) in ALT cells revealed elongated and shortened telomeres, partly in unusual configurations and loci, dicentric marker chromosomes and signal-free chromosome ends. Free ends give rise to end-to-end associations and may induce breakage-fusion-bridge cycles resulting in an increased number of complex chromosomal rearrangements, as detected by multiplex-FISH (M-FISH). We propose that ALT cannot be seen as an equivalent to telomerase activity in telomere maintenance. Its association with telomere dysfunction and chromosomal instability may have major implications for tumor progression.

p53-dependent non-coding RNA networks in chronic lymphocytic leukemia.

Mutations of the tumor suppressor p53 lead to chemotherapy resistance and a dismal prognosis in chronic lymphocytic leukemia (CLL). Whereas p53 targets are used to identify patient subgroups with impaired p53 function, a comprehensive assessment of non-coding RNA targets of p53 in CLL is missing. We exploited the impaired transcriptional activity of mutant p53 to map out p53 targets in CLL by small RNA sequencing. We describe the landscape of p53-dependent microRNA/non-coding RNA induced in response to DNA damage in CLL. Besides the key p53 target miR-34a, we identify a set of p53-dependent microRNAs (miRNAs; miR-182-5p, miR-7-5p and miR-320c/d). In addition to miRNAs, the long non-coding RNAs (lncRNAs) nuclear enriched abundant transcript 1 (NEAT1) and long intergenic non-coding RNA p21 (lincRNA-p21) are induced in response to DNA damage in the presence of functional p53 but not in CLL with p53 mutation. Induction of NEAT1 and lincRNA-p21 are closely correlated to the induction of cell death after DNA damage. We used isogenic lymphoma cell line models to prove p53 dependence of NEAT1 and lincRNA-p21. The current work describes the p53-dependent miRNome and identifies lncRNAs NEAT1 and lincRNA-p21 as novel elements of the p53-dependent DNA damage response machinery in CLL and lymphoma.

Phase III trial of bortezomib, cyclophosphamide and dexamethasone (VCD) versus bortezomib, doxorubicin and dexamethasone (PAd) in newly diagnosed myeloma.

We aimed at demonstrating non-inferiority of bortezomib/cyclophosphamide/dexamethasone (VCD) compared to bortezomib/doxorubicin/dexamethasone (PAd) induction therapy with respect to very good partial response rates or better (⩾VGPR) in 504 newly diagnosed, transplant-eligible multiple myeloma patients. VCD was found to be non-inferior to PAd with respect to ⩾VGPR rates (37.0 versus 34.3%, P=0.001). The rates of progressive disease (PD) were 0.4% (VCD) versus 4.8% (PAd; P=0.003). In the PAd arm, 11 of 12 patients with PD had either renal impairment (creatinine ⩾2 mg/dl) at diagnosis or the cytogenetic abnormality gain 1q21, whereas no PD was observed in these subgroups in the VCD arm. Leukocytopenia/neutropenia (⩾3°) occurred more frequently in the VCD arm (35.2% versus 11.3%, P<0.001). Neuropathy rates (⩾2°) were higher in the PAd group (14.9 versus 8.4%, P=0.03). Serious adverse events, both overall and those related to thromboembolic events, were higher in the PAd group (32.7 versus 24.0%, P=0.04 and 2.8 versus 0.4%, P=0.04). Stem cell collection was not impeded by VCD. VCD is as effective as PAd in terms of achieving ⩾VGPR rates with fewer PD and has a favorable toxicity profile. Therefore, VCD is preferable to PAd as induction therapy.

Mapping the gene causing hereditary primary hyperparathyroidism in a Portuguese kindred to chromosome 1q22-q31.

A Portuguese kindred with autosomal dominant isolated primary hyperparathyroidism (HPT) that was associated with parathyroid adenomas and carcinomas was investigated with the aim of determining the chromosomal location of this gene, designated HPTPort. Leukocyte DNA from 9 affected and 16 unaffected members and 7 parathyroid tumors from 4 patients was used in comparative genomic hybridization (CGH), tumor loss of heterozygosity (LOH), and family linkage studies. The CGH studies revealed abnormalities of chromosomes 1 and 13, and the results of LOH studies were consistent with the involvements of tumor suppressor genes from these regions. Family segregation studies mapped HPTPort to chromosome 1q22-q31 by establishing linkage with eight loci (D1S254, D1S222, D1S202, D1S238, D1S428, D1S2877, D1S422, and D1S412) (peak two-point LOD scores = 3. 46-5.14 at 0% recombination), and defined the location of HPT Port to a 21 cM region flanked centromerically by D1S215 and telomerically by D1S306. Thus, HPTPort has been mapped to chromosome 1q22-q31, and a characterization of this gene will help to elucidate further the mechanisms that are involved in the development of parathyroid tumors.

Genetics of neuroendocrine and carcinoid tumours.

Neuroendocrine tumours (NETs) originate in tissues that contain cells derived from the embryonic neural crest, neuroectoderm and endoderm. Thus, NETs occur at many sites in the body, although the majority occur within the gastro-entero-pancreatic axis and can be subdivided into those of foregut, midgut and hindgut origin. Amongst these, only those of midgut origin are generally argentaffin positive and secrete serotonin, and hence only these should be referred to as carcinoid tumours. NETs may occur as part of complex familial endocrine cancer syndromes, such as multiple endocrine neoplasia type 1 (MEN1), although the majority occur as non-familial (i.e. sporadic) isolated tumours. Molecular genetic studies have revealed that the development of NETs may involve different genes, each of which may be associated with several different abnormalities that include point mutations, gene deletions, DNA methylation, chromosomal losses and chromosomal gains. Indeed, the foregut, midgut and hindgut NETs develop via different molecular pathways. For example, foregut NETs have frequent deletions and mutations of the MEN1 gene, whereas midgut NETs have losses of chromosome 18, 11q and 16q and hindgut NETs express transforming growth factor-alpha and the epidermal growth factor receptor. Furthermore, in lung NETs, a loss of chromosome 3p is the most frequent change and p53 mutations and chromosomal loss of 5q21 are associated with more aggressive tumours and poor survival. In addition, methylation frequencies of retinoic acid receptor-beta, E-cadherin and RAS-associated domain family genes increase with the severity of lung NETs. Thus the development and progression of NETs is associated with specific genetic abnormalities that indicate the likely involvement of different molecular pathways.

Genetic characterization of a human skin carcinoma progression model: from primary tumor to metastasis.

The type and number of genetic aberrations required for a fully malignant tumor are still unclear. This study describes the genetic analysis of a series of skin squamous cell carcinomas, representing the primary tumor, two recurrences, and a metastatic lesion from a single patient and cell lines established therefrom (MET-1 to MET-4). Comparative genomic hybridization demonstrated that: (i) most of the gains and losses were common for tumors and cell lines and affected chromosomes 3 (3p loss, 3q gain), 5 (5p gain, 5q loss), 7 (7p gain), 8 (8p loss, 8q gain), 11 (11q gain), and 17 (17p loss), and (ii) only one aberration was present in a tumor but not in the cell line (10 loss in tumor 4); and only few aberrations were cell line specific. From these, 10p loss and 17q gain were shared by all lines and tumor 4, suggesting that they were already present in all tumors, although in only a subpopulation of cells, whereas 20q gain (shared by all lines), 4q loss (MET-2), and 18p gain/18q loss (MET-3) seem to be culture derived. In agreement, multiplex fluorescence in situ hybridization demonstrated a set of common translocations for all lines thereby further confirming their common origin. In addition, each cell line, exhibited one or more individual translocation chromosomes, which suggested that MET-1 was a precursor of MET-4, whereas MET-2 and MET-3 developed in parallel. Whereas MET-1 to MET-3 were hypodiploid or hyperdiploid, MET-4 was characterized by polyploidization, a set of specific aberrations (t(3;7), t(X;2), i(10q)), and increased heterogeneity (varying translocations in individual metaphases). Using sequencing and expression studies, cells from all lines were wild type for p53, did not exhibit mutations in any of the ras genes (Harvey, Kirsten, or N-ras), and expressed wild-type fragile histidine triad gene (FHIT; mapped to 3p14.2, a locus underrepresented in all cells) transcripts. Thus, with the MET cell lines we present an in vivo skin carcinoma progression model that was genetically well defined, and which, despite originating from a sun-exposed site, is wild type for p53.

Detection of a concomitant distal deletion in an inverted duplication of chromosome 3. Is there an overall mechanism for the origin of such duplications/deficiencies?

We describe the first inverted duplication of the p21.3p26 region of chromosome 3 in a child with phenotypic features of the trisomy 3p syndrome. This uncommon type of aberration was verified by multicolour fluorescence in situ hybridisation (FISH) using yeast artificial chromosome (YAC) clones from chromosome 3 (CEPH library). With a newly constructed YAC clone from the 3p26 region an unexpected subtelomeric deletion was diagnosed in the aberrant chromosome 3. Using the primed in situ labelling (PRINS) method, telomeres were found to be present on the recombinant chromosome 3. The repeated appearance of concomitant distal deletions in inverted duplications suggests that an overall mechanism exists for the origin of such duplications/deficiencies.