Initial Experience with Determination of hTERC and MYCC Amplification in Cervical Intraepithelial Neoplasia and Cervical Carcinoma in the Czech Republic

Tumours are frequently characterised by series of cytogenetic abnormalities. Amplifications of the human telomerase gene hTERC (3q26) and myelocytomatosis-C proto-oncogeneMYCC(8q24) have been associated with cervical intraepithelial neoplasia (CIN) and carcinoma of the uterine cervix. The results of genetic analysis allow to select patients at high risk of progression from CIN to carcinoma. Our group conducted a study in which the chromosomal abnormalities found in the cytology specimens of 26 patients with either cervical cancer or CIN were analysed using the recently developed triple-colour human papillomavirus-fluorescencein situhybridisation (HPV-FISH) assay. HPV infection was proven in 22 (85 %) patients. Amplification ofMYCCandhTERCwas found in 11 (42 %) and 16 (62 %) patients, respectively. Based on these results, the patients were divided into high-risk, medium-risk and low-risk groups. The study confirmed that the HPV-FISH assay can be used as an effective diagnostic procedure to identify patients carrying high-risk HPV infection and chromosomal aberrations associated with the development of malignancy. Patients in the high-risk group would require more frequent folllow-up and aggressive therapy.

Prognostic impact of p53 aberrations for R-CHOP-treated patients with diffuse large B-cell lymphoma

Diffuse large B-cell lymphoma (DLBCL) is the most frequent lymphoma in adults. There are specific alterations that appear repeatedly in DLBCL cases and play a role in lymphomagenesis or progression of the disease. Some aberrations were used as prognostic markers in the pre-rituximab era. Addition of rituximab to the classical anthracycline-based chemotherapy significantly increased the survival rate in DLBCL. Only few prognostic factors have been re-evaluated for patients treated with R-CHOP (rituximab, cyclophosphamide, doxorubicin, vincristine and prednisone). We performed complex analysis of the p53 tumor suppressor in collection of 75 DLBCL cases. Fifty-four patients were de novo cases, twenty-one cases developed into DLBCL by transformation from less aggressive disease. We determined functional status by analysis of separated alleles in yeast (FASAY) and analyzed the p53 mutations by cDNA sequencing. We assessed the level of the p53 protein by immunoblot analysis. We used FISH to analyze loss of the p53 and ATM (ataxia telangiectasia mutated) gene deletions. We detected 16 p53 mutations (21.3%) including the mutation activating non-sense-mediated RNA decay pathway. Deletion of the p53 allele was more common in cases with p53 mutation. Mutations and/or deletions of p53 had statistically significant negative impact on progression-free survival and tended to decrease also overall survival in 46 de novo DLBCL patients treated with R-CHOP. p53 aberrations are negative predictors for survival of DLBCL patients treated with R-CHOP.

Missense mutations located in structural p53 DNA-binding motifs are associated with extremely poor survival in chronic lymphocytic leukemia

PURPOSE

There is a distinct connection between TP53 defects and poor prognosis in chronic lymphocytic leukemia (CLL). It remains unclear whether patients harboring TP53 mutations represent a homogenous prognostic group.

PATIENTS AND METHODS

We evaluated the survival of patients with CLL and p53 defects identified at our institution by p53 yeast functional assay and complementary interphase fluorescence in situ hybridization analysis detecting del(17p) from 2003 to 2010.

RESULTS

A defect of the TP53 gene was identified in 100 of 550 patients. p53 mutations were strongly associated with the deletion of 17p and the unmutated IgVH locus (both P < .001). Survival assessed from the time of abnormality detection was significantly reduced in patients with both missense (P < .001) and nonmissense p53 mutations (P = .004). In addition, patients harboring missense mutation located in p53 DNA-binding motifs (DBMs), structurally well-defined parts of the DNA-binding domain, manifested a clearly shorter median survival (12 months) compared with patients having missense mutations outside DBMs (41 months; P = .002) or nonmissense alterations (36 months; P = .005). The difference in survival was similar in the analysis limited to patients harboring mutation accompanied by del(17p) and was also confirmed in a subgroup harboring TP53 defect at diagnosis. The patients with p53 DBMs mutation (at diagnosis) also manifested a short median time to first therapy (TTFT; 1 month).

CONCLUSION

The substantially worse survival and the short TTFT suggest a strong mutated p53 gain-of-function phenotype in patients with CLL with DBMs mutations. The impact of p53 DBMs mutations on prognosis and response to therapy should be analyzed in investigative clinical trials.

Monozygotic twins with discordant karyotypes following preimplantation genetic screening and single embryo transfer: case report

PURPOSE

to report a case of monozygotic monochorial diamniotic twins with discordant karyotypes.

METHODS AND RESULTS

the pregnancy was achieved following a treatment cycle with intracytoplasmic sperm injection (ICSI) and preimplantation genetic screening (PGS) for chromosomes X, Y, 13, 16, 18, 21, 22. One embryo euploid for studied chromosomes was transferred. Prenatal ultrasonography revealed monozygotic twins. One fetus had growth retardation, multiple organ abnormalities and polyhydramnion. The other twin had normal ultrasound appearance. Delivery on week 29 of gestation resulted in the birth of two females, a stillborn twin with karyotype 45,XX,-13[12]/46,XX,r(13)[3] and a healthy twin with normal karyotype.

CONCLUSIONS

the discordance in the twins' karyotypes originated from a mosaic embryo. Structural chromosomal abnormality of the affected twin could not be revealed using standard PGS investigation. Embryo splitting occurred probably due to apoptotic process in an early stage of embryo development. Apoptosis represents one of the possible mechanisms which can explain the embryo twinning process globally.

Low-level copy number changes of MYC genes have a prognostic impact in medulloblastoma

High-level amplifications of MYC genes are associated with poor outcomes in childhood medulloblastoma (MB). However, the occurrence of MYCN and MYCC copy number increases below the intense amplification pattern is rarely reported, and its clinical impact has not yet been determined. Here, we describe this phenomenon and its prognostic significance in a cohort of 29 MB patients. Using interphase fluorescence in situ hybridization (I-FISH), low-level copy number alterations, i.e. gain of MYCN, were shown in 5/27 (19%) samples, whereas amplification was revealed in only 1/27 (4%) samples. MYCC gain was revealed in 6/29 (21%) MB, while amplification was disclosed in only 2/29 (7%). Hyperploidy and co-incidence of gains in both MYC loci were frequently observed in samples with copy number aberrations. Survival analysis has clearly shown that MYC copy number increases are associated with lowered event-free survival and overall survival in MB. In the case of MYCN, this negative correlation was statistically significant. We conclude that limited numerical alterations in loci 2p24 (MYCN) and 8q24 (MYCC), as assessed by I-FISH, are present in MB with a higher frequency than high-level amplifications. Poor prognoses were observed in patients with copy number increases in MYC genes. Our data illustrate the importance of further investigations in multicenter trials to better refine the emerging genomic-based prognostic stratification in MB.

Efficacy of high-resolution comparative genomic hybridization (HR-CGH) in detection of chromosomal abnormalities in children with acute leukaemia

The efficient detection of chromosomal aberrations in childhood acute leukaemias presents a significant component in the diagnostics of this frequent malignant disease. We used comparative genomic hybridization (CGH) and high-resolution comparative genomic hybridization (HR-CGH) to determine the frequency of chromosomal changes in 33 children with acute leukaemia (AL). The yields of chromosomal abnormalities were compared with the results obtained using conventional cytogenetics (G-banding) and fluorescence in situ hybridization (FISH). Conventional cytogenetics revealed chromosomal changes in 17 (52 %) of studied patients. The employment of FISH together with G-banding analysis identified chromosomal changes in 27 (82 %) of the AL patients investigated. CGH detected changes in DNA copy numbers in 24 (73 %) patients, 40 losses and 67 gains were found in total. HR-CGH disclosed 98 losses and 97 gains in 26 (79 %) patients. In comparison with CGH, HR-CGH analyses unveiled 88 new chromosomal aberrations: 58 losses and 30 gains. The most commonly gained chromosomes were 21 (22.5 %), X (15 %), 18 (12,5 %) and 17 (10 %). The most common losses involved sub-regions or arms of chromosomes 7 (15 %), 9 (12.5 %), 16, 19 and 1 (10 % each). Cytogenetic and molecular cytogenetic analyses of 33 childhood acute leukaemias revealed chromosomal changes in total 31 (94 %) patients. The evaluation of HR-CGH sensitivity proved that the minimal cell population of malignant cells in which a certain chromosomal change could be found was close to the 20 - 30 % level. Our results confirm the benefits of HR-CGH in detecting chromosomal changes in childhood AL. Supplementing G-banding and FISH with the HR-CGH diagnostic method increases the detection of unbalanced structural chromosomal rearrangements and can reveal small cell clones with gains and losses of whole chromosomes in hyperdiploid AL.

Identification of 2.3-Mb Gene Locus for Congenital Aural Atresia in 18q22.3 Deletion

OBJECTIVE

18q deletion syndrome is a multiple-anomaly mental retardation syndrome associated with congenital aural atresia. The purpose of this study was to determine the frequency of the congenital aural atresia phenotype in 18q deletion syndrome patients and to delineate a potential critical region for congenital aural atresia at the 18q22.3-18q23 region.

STUDY DESIGN AND PATIENTS

The study describes one 18q deletion syndrome clinical report (Patient 15) with an overview of 19 other selected 18q deletion syndrome patients presenting congenital aural atresia from 18 published articles and one presented poster on 18q deletion syndrome.

RESULTS

Our investigation, together with the results of published 18q deletion syndrome reports, shows that the average frequency of congenital aural atresia is approximately 52%. A combination of three 18q deletion syndrome probands defines a chromosomal deletion site for congenital aural atresia at 18q22.3-18q23 in the region between markers D18S489 and D18S554. These polymorphic markers outline a putative critical interval of approximately 2.3 Mb, including the genes ZNF407, ZADH2, SDCCAG33, ZNF516, FLJ44881, ZNF236, MBP-Golli, and GALR1. The haploinsufficiency of these genes is suggested to be a primary cause of congenital aural atresia phenotype in 18q deletion syndrome individuals.

CONCLUSION

Congenital aural atresia is a relevant diagnostic clue and a major recognizable feature of 18q deletion syndrome. Early diagnosis of 18q deletion syndrome may enable application of hearing aids. Knockout studies on the congenital aural atresia mouse gene homolog may add further insight into the genes responsible for this condition.