This is an RSS newsfeed from BioMed Central It is intended to be used with an RSS reader. For more information about RSS newsfeeds from BioMed Central, visit http://www.biomedcentral.com/info/about/rss/ http://www.molecularcytogenetics.org The latest articles from Molecular Cytogenetics (ISSN 1755-8166) published by BioMed Central Background: Nuclear architecture studies in human sperm are sparse. By now performed ones were practically all done on flattened nuclei. Thus, studies close at the in vivo state of sperm, i.e. on three-dimensionally conserved interphase cells, are lacking by now. Only the position of 14 chromosomes in human sperm was studied. Results: Here for the first time a combination of multicolor banding (MCB) and three-dimensional analysis of interphase cells was used to characterize the position and orientation of all human chromosomes in sperm cells of a healthy donor. The interphase nuclei of human sperm are organized in a non-random way, driven by the gene density and chromosome size. Conclusions: Here we present the first comprehensive results on the nuclear architecture of normal human sperm. Future studies in this tissue type, e.g. also in male patients with unexplained fertility problems, may characterize yet unknown mechanisms of infertility. http://www.molecularcytogenetics.org/content/1/1/25 Marina Manvelyan, Friederike Hunstig, Samarth Bhatt, Kristin Mrasek, Franck Pellestor, Anja Weise, Isabella Simonyan, Rouben Aroutiounian and Thomas Liehr Molecular Cytogenetics 2008, 1:25 2008-11-14 doi:10.1186/1755-8166-1-25 Molecular Cytogenetics 1755-8166 1 25 2008-11-14 We report a 7 years and 4 months old Greek boy with mild microcephaly and dysmorphic facial features. He was a sociable child with maxillary hypoplasia, epicanthal folds, upslanting palpebral fissures with long eyelashes, and hypertelorism. His ears were prominent with dysmorphic auricles, he had a long philtrum and a gothic palate. His weight was 17 kg (25th percentile) and his height 120 cm (50th percentile). High resolution chromosome analysis identified in 50% of the cells a normal male karyotype, and in 50% of the cells the one chromosome 18 showed a terminal deletion from 18q21.32. Molecular cytogenetic investigation confirmed a del(18)(q21.32-qter) in the one chromosome 18, but furthermore revealed the presence of a duplication in q21.2 in the other chromosome 18. The case is discussed concerning comparable previously reported cases and the possible mechanisms of formation. http://www.molecularcytogenetics.org/content/1/1/24 Emmanouil Manolakos, Nadezda Kosyakova, Loreta Thomaidis, Rozita Neroutsou, Anja Weise, Markos Mihalatos, Sandro Orru, Haris Kokotas, George Kitsos, Thomas Liehr and Michael Petersen Molecular Cytogenetics 2008, 1:24 2008-11-11 doi:10.1186/1755-8166-1-24 Molecular Cytogenetics 1755-8166 1 24 2008-11-11 Background: Jacobsen syndrome is a rare contiguous gene disorder that results from a terminal deletion of the long arm of chromosome 11. It is typically characterized by intellectual disability, a variety of physical anomalies and a distinctive facial appearance. The 11q deletion has traditionally been identified by routine chromosome analysis. Array-based comparative genomic hybridization (array-CGH) has offered new opportunities to identify and refine chromosomal abnormalities in regions known to be associated with clinical syndromes. Results: Using the 1 Mb BAC array (Spectral Genomics), we screened 70 chromosomally normal children with idiopathic intellectual disability (ID) and congenital abnormalities, and identified five cases with submicroscopic abnormalities believed to contribute to their phenotypes. Here, we provide detailed molecular cytogenetic descriptions and clinical presentation of two unrelated subjects with de novo submicroscopic deletions within chromosome bands 11q24-25. In subject 1 the chromosome rearrangement consisted of a 6.18 Mb deletion (from 128.25-134.43 Mb) and an adjacent 5.04 Mb duplication (from 123.15-128.19 Mb), while in subject 2, a 4.74 Mb interstitial deletion was found (from 124.29-129.03 Mb). Higher resolution array analysis (385K Nimblegen) was used to refine all breakpoints. Deletions of the 11q24-25 region are known to be associated with Jacobsen syndrome (JBS: OMIM 147791). However, neither of the subjects had the typical features of JBS (trigonocephaly, platelet disorder, heart abnormalities). Both subjects had ID, dysmorphic features and additional phenotypic abnormalities: subject 1 had a kidney abnormality, bilateral preauricular pits, pectus excavatum, mild to moderate conductive hearing loss and behavioral concerns; subject 2 had macrocephaly, an abnormal MRI with delayed myelination, fifth finger shortening and squaring of all fingertips, and sensorineural hearing loss. Conclusions: Two individuals with ID who did not have the typical clinical features of Jacobsen syndrome were found to have deletions within the JBS region at 11q24-25. Their rearrangements facilitate the refinement of the JBS critical region and suggest that a) deletion of at least 3 of the 4 platelet function critical genes (ETS-1, FLI-1 and NFRKB and JAM3) is necessary for thrombocytopenia; b) one of the critical regions for heart abnormalities (conotruncal heart defects) may lie within 129.03 - 130.6 Mb; c) deletions of KCNJ1 and ADAMTS15 may contribute to the renal anomalies in Jacobsen Syndrome; d) the critical region for MRI abnormalities involves a region from 124.6 - 129.03 Mb. Our results reiterate the benefits of array-CGH for description of new phenotype/genotype associations and refinement of previously established ones. http://www.molecularcytogenetics.org/content/1/1/23 Christine Tyson, Ying Qiao, Chansonette Harvard, Xudong Liu, Francois P Bernier, Barbara McGillivray, Sandra A Farrell, Laura Arbour, Albert E Chudley, Lorne Clarke, William Gibson, Sarah Dyack, Ross McLeod, Teresa Costa, Margot I VanAllen, Siu-li Yong, Gail E Graham, Patrick MacLeod, Millan S Patel, Jane Hurlburt, Jeanette JA Holden, Suzanne ME Lewis and Evica Rajcan-Separovic Molecular Cytogenetics 2008, 1:23 2008-11-11 doi:10.1186/1755-8166-1-23 Molecular Cytogenetics 1755-8166 1 23 2008-11-11 Background: Murine myeloid leukemia (ML) provides a good animal model to study the mechanisms of radiation-induced leukemia in humans. This disease has been cytogenetically characterized by a partial deletion of chromosome 2 with G-banding. For the rapid diagnosis of ML, this study reports a FISH method using spleen cells and peripheral blood smears from ML mice exposed to gamma rays and neutrons with PU.1, a candidate ML tumor suppressor, as a probe. Results: Among mice that were tentatively diagnosed with ML by clinical findings and blood smear examination, 85% carried spleen cells showing the loss of PU.1 although the frequency of these abnormal cells varied among individuals. Mice with very low frequencies of cells showing the loss of one copy of PU.1 (one-PU.1 frequency) were later diagnosed pathologically not with ML but with blastic or eosinophilic leukemia. Some neutron-irradiated mice had cells showing translocated PU.1, although no pathological features differentiated these ML mice from ML mice expressing the simple loss of PU.1.The one-PU.1 frequency can be detected from spleen metaphase cells, spleen interphase cells, and blood smears. There was a good correlation between the one-PU.1 frequency in spleen metaphase cells and that in spleen interphase cells (r = 0.96) and between one-PU.1 frequency in spleen interphase cells and that in blood cells (r = 0.83). Conclusion: The FISH method was capable of detecting aberration of copy number of the PU.1 gene on murine chromosome 2, and using a peripheral blood smear is more practical and less invasive than conventional pathological diagnosis or the cytogenetic examination of spleen cells. http://www.molecularcytogenetics.org/content/1/1/22 Reiko Kanda, Satsuki Tsuji, Yasushi Ohmachi, Yuka Ishida, Nobuhiko Ban and Yoshiya Shimada Molecular Cytogenetics 2008, 1:22 2008-10-16 doi:10.1186/1755-8166-1-22 Molecular Cytogenetics 1755-8166 1 22 2008-10-16 Background: Down syndrome, characterized by an extra chromosome 21 is the most common genetic cause for congenital malformations and learning disability. It is well known that the extra chromosome 21 most often originates from the mother, the incidence increases with maternal age, there may be aberrant maternal chromosome 21 recombination and there is a higher recurrence in young women. In spite of intensive efforts to understand the underlying reason(s) for these characteristics, the origin still remains unknown. We hypothesize that maternal trisomy 21 ovarian mosaicism might provide the major causative factor. Results: We used fluorescence in situ hybridization (FISH) with two chromosome 21-specific probes to determine the copy number of chromosome 21 in ovarian cells from eight female foetuses at gestational age 14–22 weeks. All eight phenotypically normal female foetuses were found to be mosaics, containing ovarian cells with an extra chromosome 21. Trisomy 21 occurred with about the same frequency in cells that had entered meiosis as in pre-meiotic and ovarian mesenchymal stroma cells. Conclusion: We suggest that most normal female foetuses are trisomy 21 ovarian mosaics and the maternal age effect is caused by differential selection of these cells during foetal and postnatal development until ovulation. The exceptional occurrence of high-grade ovarian mosaicism may explain why some women have a child with Down syndrome already at young age as well as the associated increased incidence at subsequent conceptions. We also propose that our findings may explain the aberrant maternal recombination patterns previously found by family linkage analysis. http://www.molecularcytogenetics.org/content/1/1/21 Maj A Hultén, Suketu D Patel, Maira Tankimanova, Magnus Westgren, Nikos Papadogiannakis, Anna Maria Jonsson and Erik Iwarsson Molecular Cytogenetics 2008, 1:21 2008-09-18 doi:10.1186/1755-8166-1-21 Molecular Cytogenetics 1755-8166 1 21 2008-09-18 Malignant melanomas are characterized by increased karyotypic complexity, extended aneuploidy and heteroploidy. We report a melanoma metastasis to the peritoneal cavity with an exceptionally stable, abnormal pseudodiploid karyotype as verified by G-Banding, subtelomeric, centromeric and quantitative Fluorescence in Situ Hybridization (FISH). Interestingly this tumor had no detectable telomerase activity as indicated by the Telomere Repeat Amplification Protocol. Telomeric Flow-FISH and quantitative telomeric FISH on mitotic preparations showed that malignant cells had relatively short telomeres. Microsatellite instability was ruled out by the allelic pattern of two major mononucleotide repeats. Our data suggest that a combination of melanoma specific genomic imbalances were sufficient and enough for this fatal tumor progression, that was not accompanied by genomic instability, telomerase activity, or the engagement of the alternative recombinatorial telomere lengthening pathway. http://www.molecularcytogenetics.org/content/1/1/20 Sarantis Gagos, George Papaioannou, Maria Chiourea, Sophie Merk-Loretti, Charles-Edward Jefford, Panagiota Mikou, Irmgard Irminger-Finger, Anna Liossi, Jean-Louis Blouin and Sophie Dahoun Molecular Cytogenetics 2008, 1:20 2008-08-22 doi:10.1186/1755-8166-1-20 Molecular Cytogenetics 1755-8166 1 20 2008-08-22 Background: Small supernumerary marker chromosomes (sSMC) occur in 0.075% of unselected prenatal and in 0.044% of consecutively studied postnatal cases. Individuals with sSMC present with varying phenotype, ranging from normal to extremely mild or severe depending on the chromosomal region involved, the euchromatic content present and degree of mosaicism. Except for chromosomes 15 and 22, the number of reported cases of sSMC is extremely small to provide us with a good genotype-phenotype correlation. Analphoid sSMC are even rarer. To our knowledge only eight cases of analphoid inversion-duplication 3q sSMC are reported so far. Results: We describe here a one month old female child with several dysmorphic features and with a de novo analphoid supernumerary marker chromosome only in cultured skin fibroblast cells and not in lymphocytes. The marker was characterized as analphoid inversion-duplication 3q25.33-qter by oligo array comparative genomic hybridization (aCGH) and fluorescence in situ hybridization (FISH) studies. The final skin fibroblast karyotype was interpreted as 47,XX,+der(3).ish inv dup(3)(qter-q25.33::q25.33-qter)(subtel 3q+,subtel 3q+) de novo. Conclusion: In addition to the eight reported cases of analphoid inversion-duplication 3q supernumerary marker in the literature, this is yet another case of 3q sSMC with a new breakpoint at 3q25.33 and with varying phenotype as described in the case report. Identification of more and more similar cases of analphoid inversion-duplication 3q marker will help in establishing a better genotype-phenotype correlation. The study further demonstrates that aCGH in conjunction with routine cytogenetics and FISH is very useful in precisely identifying and characterizing a marker chromosome, and more importantly help in providing with an accurate genetic diagnosis and better counseling to the family. http://www.molecularcytogenetics.org/content/1/1/19 Sabita K Murthy, Ashok K Malhotra, Preenu S Jacob, Sehba Naveed, Eman EM Al-Rowaished, Sara Mani, Shabeer Padariyakam, R Pramathan, Ravi Nath, Mahmoud Taleb Al-Ali and Lihadh Al-Gazali Molecular Cytogenetics 2008, 1:19 2008-08-14 doi:10.1186/1755-8166-1-19 Molecular Cytogenetics 1755-8166 1 19 2008-08-14 Chromosome 22q11.2 microdeletion syndrome is due to microdeletion of 22q11.2 region of chromosome 22. It is a common microdeletion syndrome however mosaic cases are very rare and reported only few previous occasions. In this report we describe two unrelated male children with clinical features consistent with 22q11.2 microdeletion syndrome characterized by cardiac defect, facial dysmorphism and developmental deficiency. One of the cases also had trigonocephaly. Interphase & metaphase FISH with 22q11.2 probe demonstrated mosaicism for hemizygous deletion of 22q11.2 region. Mosaicism is also observed in buccal cells as well as urine cells. Parents were without any deletion. These two cases represent rare cases of mosaic 22q11.2 microdeletion syndrome. http://www.molecularcytogenetics.org/content/1/1/18 Ashutosh Halder, Manish Jain, Madhulika Kabra and Neerja Gupta Molecular Cytogenetics 2008, 1:18 2008-08-10 doi:10.1186/1755-8166-1-18 Molecular Cytogenetics 1755-8166 1 18 2008-08-10 Background: Complex chromosomal rearrangements (CCRs) are defined as structural chromosomal rearrangements with at least three breakpoints and exchange of genetic material between two or more chromosomes. Complex chromosomal translocations are rarely seen in the general population but the frequency of occurrence is anticipated to be much higher due balanced states with no phenotypic presentation. Here, we report a severely mentally retarded fertile male patient in whom further delineation of CCR involving chromosomes 1, 4 and 2 was carried out by using high resolution multicolor banding (MCB) technique. As a FISH based novel chromosome banding approach, high resolution MCB allows for the differentiation of chromosome region specific areas at band and subband levels. Results: Cytogenetic studies using high resolution banding of the proband necessitated further delineation of the breakpoints because of their uncertainty: 46,XY,t(1;4;2)(p21~31;q31.3;q31). After using high resolution MCB based on microdissection derived region-specific libraries, the exact nature of chromosomal rearrangements for chromosomes 1, 2 and 4 were revealed and these breakpoints were located on 1p31.1, 1q24.3 and 4q31.3 giving rise to a balanced situation. Conclusion: Further delineations are certainly required to provide detailed information about the relationship between balanced CCRs and their phenotypes in order to offer proper counseling to the families concerned. Carriers must be investigated with high resolution banding and molecular cytogenetic techniques to determine the exact locations of the breakpoints. High resolution MCB is an alternative and an efficient method to other FISH based chromosome banding techniques and can serve in clarifying the nature of CCR. http://www.molecularcytogenetics.org/content/1/1/17 Nilüfer Karadeniz, Kristin Mrasek and Anja Weise Molecular Cytogenetics 2008, 1:17 2008-08-07 doi:10.1186/1755-8166-1-17 Molecular Cytogenetics 1755-8166 1 17 2008-08-07 We report a patient with a unique and complex cytogenetic abnormality involving mosaicism for a small ring X and deleted Xp derivative chromosome with tandem duplication at the break point. The patient presented with failure to thrive, muscular hypotonia, and minor facial anatomic anomalies, all concerning for Turner syndrome. Brain MRI revealed mild thinning of the corpus callosum, an apparent decrease in ventricular white matter volume, and an asymmetric myelination pattern. Array comparative genome hybridization analysis revealed mosaicism for the X chromosome, deletion of the short arm of an X chromosome, and a duplication of chromosome region Xp11.21-p11.22. G-banded chromosome and FISH analyses revealed three abnormal cell lines: 46,X,der(X)del(X)(p11.23)dup(X)(p11.21p11.22)/46,X,r(X)(q11.1q13.1)/45,X. The small ring X chromosome was estimated to be 5.2 Mb in size and encompassed the centromere and Xq pericentromeric region. X chromosome inactivation (XCI) studies demonstrated a skewed pattern suggesting that the ring X remained active, likely contributing to the observed clinical features of brain dysmyelination. We hypothesize that a prezygotic asymmetric crossing over within a loop formed during meiosis in an X chromosome with a paracentric inversion resulted in an intermediate dicentric chromosome. An uneven breakage of the dicentric chromosome in the early postzygotic period might have resulted in the formation of one cell line with the X chromosome carrying a terminal deletion and pericentromeric duplication of the short arm and the second cell line with the X chromosome carrying a complete deletion of Xp. The cell line carrying the deletion of Xp could have then stabilized through self-circularization and formation of the ring X chromosome. http://www.molecularcytogenetics.org/content/1/1/16 Oleg A Shchelochkov, M Lance Cooper, Zhishuo Ou, Sandra Peacock, Svetlana A Yatsenko, Chester W Brown, Ping Fang, Pawel Stankiewicz and Sau Wai Cheung Molecular Cytogenetics 2008, 1:16 2008-07-25 doi:10.1186/1755-8166-1-16 Molecular Cytogenetics 1755-8166 1 16 2008-07-25