Application of molecular cytogenetic techniques to clarify apparently balanced complex chromosomal rearrangements in two patients with an abnormal phenotype: case report
© de Vree et al; licensee BioMed Central Ltd. 2009
Received: 28 May 2009
Accepted: 13 July 2009
Published: 13 July 2009
Complex chromosomal rearrangements (CCR) are rare cytogenetic findings that are difficult to karyotype by conventional cytogenetic analysis partially because of the relative low resolution of this technique. High resolution genotyping is necessary in order to identify cryptic imbalances, for instance near the multiple breakpoints, to explain the abnormal phenotype in these patients. We applied several molecular techniques to elucidate the complexity of the CCRs of two adult patients with abnormal phenotypes.
Multicolour fluorescence in situ hybridization (M-FISH) showed that in patient 1 the chromosomes 1, 10, 15 and 18 were involved in the rearrangement whereas for patient 2 the chromosomes 5, 9, 11 and 13 were involved. A 250 k Nsp1 SNP-array analysis uncovered a deletion in chromosome region 10p13 for patient 1, harbouring 17 genes, while patient 2 showed no pathogenic gains or losses. Additional FISH analysis with locus specific BAC-probes was performed, leading to the identification of cryptic interstitial structural rearrangements in both patients.
Application of M-FISH and SNP-array analysis to apparently balanced CCRs is useful to delineate the complex chromosomal rearrangement in detail. However, it does not always identify cryptic imbalances as an explanation for the abnormal phenotype in patients with a CCR.
Complex chromosomal rearrangements (CCR) are defined as structural abnormalities involving more than two breakpoints and the exchange of genetic material between two or more chromosomes . They can occur in patients who are mentally retarded or have multiple congenital abnormalities [2, 3] or in phenotypically normal individuals who are ascertained through the birth of a malformed child or fetus, repeated abortion or reproductive problems [4–6]. Until now, more than 160 patients with a CCR are reported in literature, observed both postnatally as well as prenatally [7–11]. This number will increase since the application of molecular cytogenetic techniques on apparently balanced reciprocal translocations has revealed that more cryptic rearrangements, with or without imbalance, can be found [12–17]. Multicolour fluorescence in situ hybridization (M-FISH) can visualize the complexity of structural rearrangements in one single overview, sometimes undetected by conventional cytogenetics, by applying 24 distinct colours separating one chromosome from the other [18, 19]. The application of molecular high resolution SNP-array analysis on DNA of patients with an abnormal phenotype and apparently balanced chromosome rearrangements may detect submicroscopic imbalances [20, 21] that could have an association with the disease. The combination of both techniques will lead to the identification of more chromosomal breakpoints or genomic imbalances, giving more insight into the complexity of the chromosomal rearrangements.
Here we present two adult patients with an abnormal phenotype, both with a de novo initially apparently balanced CCR determined by GTG banding. The application of M-FISH, SNP-array and FISH analysis has clarified the CCR in more detail in order to perform a genotype-phenotype study.
The patient was the second child of non-consanguineous parents. He was born by caesarian section because of a high head position. His apgar score was 9 after 1 minute. Birth parameters were normal (weight 3380 grams, length 49 cm, head circumference 37 cm). There was a slight delay in early development as walking and first words began at the age of 18 months. Further speech development was slow with poor articulation. At the age of 4 years, an autistic spectrum disorder was suspected because of stereotypic movements and typical behavioral problems. Because of his mild mental retardation he attended special education. At puberty, his weight increased with 20 kg in 2 years. Autistic behavior had diminished after puberty, though he still clung to regular daily patterns. His general health was good and vision and hearing were normal.
At the age of 15 years and 5 months, his length was 183,8 cm (+1 SD), weight 112 kg (>>+2 SD), and head circumference 60,4 cm (+2,5 SD). He had a relatively large head with bitemporal narrowing and a mildly sloping forehead. His eyebrows were full and broad. His eyes were deep-set with epicanthic folds and slightly downslanting palpebral fissures. He had a bulbous nasal tip. His palate was high and narrow. Obesity was generalized.
Analysis of the fragile X syndrome gene, FMR1, and metabolic screening were normal.
The second patient is at present 30 years old. His length is 150 cm (-4 1/2 SD), weight is 34 kg (-1 SD) and head circumference 55 cm (-1 1/2 SD). He is severely mentally retarded and is not able to walk or speak. He was born as the third child of non-consanguineous parents after an uneventful pregnancy and delivery. His birth weight was 3000 gram. His muscle tone was weak and developmental delay was obvious within six months. Chromosome analysis in 1980 already showed a translocation with involvement of chromosomes 5, 11 and 13. He had nystagmic eye movements and also epileptic activity, therefore he used antiepileptic drugs. He had sleeping problems, and autistic and self-destructive behaviour (trichotillomania, polyembolokoilamania). Increasingly, he has periods of agitation. He suffers from recurrent ear infections and has almost become blind, at least partially due to automutilation (pushing fingers or other objects in his eyes). He has an asymmetric face with a broad nose and full lips. His right eye is smaller. It is possible that a part of the facial features are the result of the automutilation. There is a highly arched palate with a bifid uvula. Because of the pregnancy of this patient's sister, re-evaluation of his cytogenetic analysis was performed.
Overview of characteristics for the BAC-probes used in this study.
FISH signal results
10p14 + der(1)
10p14 + der(1)
10p14 + der(18)
10p13 + der(18)
10p13 + der(18)
10p13 + der(18)
10p13 + der(18)
10p13 + Δ
10p13 + der(10)
5 + der(11)
5q31.1 + der(9)
5q31.2 + der(9)
5q31.3 + dic(11;13)
5q31.3 + dic(11;13)
5q32 + dic(11;13)
5q33.1 + dic(11;13)
5q33.2 + dic(11;13)
9 + der(9)
9 + der(9)
13q31.3 + dic(11;13)
13q31.3 + der(9)
13q32.1 + der(11)
13q32.1 + der(11)
13q32.3 + der(11)
Parental chromosome and FISH analysis showed normal results.
The karyotype of patient 1 was readjusted and assigned according to ISCN 2005  as follows:
Conventional banding cytogenetic analysis initially showed a complex karyotype, in which the chromosomes 5, 11 and 13 were involved: 46, XY, del(5)(q11), der(11)t(5;11)(q11;q11), der(13)t(11;13)(q11;p11). M-FISH demonstrated that the chromosomal rearrangement was more complex, and that also chromosome 9 was involved (Figure 1B). FISH with WCPs for chromosomes 5, 9, 11 and 13 and several BAC-probes confirmed the more complex result of the CCR (Table 1). Part of chromosome 5 is inserted in the q-arm of derivative chromosome 9, which was confirmed as a direct insertion with BAC-probes RP11-729C24 and RP11-114H21 (Figure 3E). Also a weak fluorescent signal of WCP 13 was detected on der(9). M-FISH results showed a slight increase of the fluorescent signals for chromosome 13 on der(9) (Figure 1D). FISH with the BAC-probe RP11-632L2 (13q31.3) showed a signal on der(9), confirming the insertion and location of chromosome 13 material into this der(9) (Figure 3F). The insertion of chromosome 5 was located centromeric to the insertion of chromosome 13.
Characterization of the der(13) with several FISH probes revealed that the centromeric probes for chromosome 11 (pLC11A) and 13 (L1.26) were both present on the derivative chromosome 13. Also FISH with the DNA-probe r521 (ribosomal satellite probe) showed that the satellite of chromosome 13 appeared to be located between these two centromeres on the dic(11;13) (data not shown). Subsequent SNP-array analysis showed several small gains and losses, ranging in size from 81 kb till 1 Mb, but all were previously reported as common CNVs in the database of genomic variants (SNP call of 92,98%; SD 0,2035) (data not shown). Since both parents showed normal karyotypes, the karyotype of patient 2 was readjusted and assigned as 46, XY, der(5)(5pter→5p10), der(9)(9pter→9q31::5q31→5q31::13q31→13q31::9q31→9qter), der(11)(13qter→13q31::5q31→5q10::11q10→11qter), dic(11;13) (11pter→11p10::13p13→13q31::5q31→5qter)dn (Figure 4B).
The aim of this study was to characterize the CCRs of two patients with multiple molecular cytogenetic techniques in order to find an explanation for their abnormal phenotype. The application of GTG banding, M-FISH and conventional FISH analysis elucidated the complex chromosomal rearrangements in two patients, each comprising four derivative chromosomes.
In patient 1 the application of a 250 k Nsp1 SNP-array analysis additionally revealed a deletion of part of chromosome 10p13 with an approximate size of 1.5 Mb, harbouring 17 genes. Using the Ingenuity Pathway Analysis program , we investigated, whether any of the 17 genes deleted on chromosome 10, could be considered as a candidate gene for mental retardation based on available expression and/or functional data. We found information in the Ingenuity database for 14 of the 17 genes (Figure 2). Four of these genes (NMT2, SUV39H2, FAM107B, FAM171A1) showed an indirect relationship with known mental retardation genes of which three genes are expressed in the nervous system (not SUV39H2). It is very likely that in patient 1 the de novo deletion is causative for his abnormal phenotype, although further examination is necessary to investigate how the deleted genes contribute to his phenotype.
It is known that chromosomal loss of the 10p13–p14 region is associated with DiGeorge syndrome type II with cardiac abnormalities . Yatsenko et al. reported one patient with a larger 10p deletion than our patient has, also including the BAC-probe RP11-393E10 which was absent in patient 1 . Despite this overlap, our patient does not have clinical signs of a congenital heart problem or other symptoms related to the DiGeorge syndrome type II, except for the developmental delay. Christian et al.  used array comparative genomic hybridization (array-CGH) to investigate 397 unrelated subjects with autism spectrum disorder. One of the included patients showed a 318 kb deletion on 10p13. However, that deletion was located adjacent to the deletion in our patient, and showed no overlap. To the best of our knowledge, there are no other reports of a correlation of the deleted 10p13 region, or of the other observed breakpoint regions with autism [28–30].
SNP-array analysis of patient 2 showed no additional pathogenic gains or losses with the 250 k Nsp1 platform. FISH revealed a clonal dicentric 11;13 chromosome in all cells. By conventional GTG-banding we observed that the dic(11;13) contained a primary constriction of the centromere 11, suggesting that the centromere 11 is the active centromere and that the centromere 13 is the inactive centromere.
At present, the abnormal phenotype of patient 2 could not be explained by a chromosomal imbalance. In the literature, up to 70% of the patients with a chromosomal rearrangement, both complex and reciprocal translocations, show no imbalance on the chromosomal or molecular level as an explanation for the phenotype . Several other molecular mechanisms have been proposed to explain the clinical problems of these patients  such as balanced translocations leading to a position effect by separating a gene from its regulatory elements altering gene-expression  or creating fusion genes. A disruption of a gene could unmask a recessive mutation on the homologue allele. Heterochromatin can also have effects on juxtaposed euchromatic regions. This heterochromatinization of euchromatic regions can (partially) silence the expression of neighbouring genes . This might be the case for the der(11) in patient 2, in which the 5q11.2 region might be under the influence of the centromere 11, possibly leading to silencing of important 5q11.2 genes. Finally, also a disruption of a dosage-sensitive gene might alter or eliminate its function, causing disease .
As more breakpoints are involved in a CCR such mechanisms as mentioned above suggest a greater chance for an abnormal phenotypic outcome . Madan et al. show that individuals with a CCR and an abnormal phenotype show a significantly higher mean (4.9) of breakpoints than the mean (3.6) of breakpoints for phenotypically normal individuals . In our study the combination of techniques revealed more cryptic rearrangements leading to a total of six breakpoints in patient 1, while patient 2 shows seven breakpoints. Although the deletion in chromosome 10 of patient 1 is assigned as a causative element, DNA rearrangements at the breakpoints could also contribute to the phenotype.
In conclusion, this study demonstrates the power of combining different molecular cytogenetic techniques to elucidate the genetic constitution of CCRs. However, next to M-FISH and high resolution SNP-array analysis, additional FISH analysis with locus specific probes is still crucial to elucidate and identify cryptic genetic abnormalities in more detail, as is demonstrated in this paper. Submicroscopic deletions or duplications will allow further genotype-phenotype correlation studies. On the other hand, the combination of all these molecular cytogenetic analyses does not always explain an abnormal phenotype in patients with a CCR.
Materials and methods
Cytogenetic analysis was performed on GTG-stained metaphase spreads obtained from cultured peripheral blood lymphocytes according to standard procedures. An Axioskop microscope (Zeiss, Sliedrecht, The Netherlands) was used for karyotyping and metaphase images were captured with Ikaros software (Metasystems, Altlussheim, Germany). Karyotypes were obtained from both patients and their parents.
Multiplex Ligation-dependent Probe Amplification (MLPA) was performed using SALSA P036B and P070 kits (MRC Holland, Amsterdam, The Netherlands) to investigate the subtelomeric regions for copy number aberrations according to Schouten et al. (2002) . Analysis was performed using Genemarker® software (SoftGenetics, State College, PA, USA).
Multicolour FISH was performed using the 24 Xcyte Human mFISH DNA Probe Kit, following manufacturer's instructions (Metasystems). The results were analysed using a Zeiss Imager.Z1 microscope with five filters for the fluorochromes used: diethylaminocoumarine (DEAC), fluorescein isothiocyanate (FITC), SpectrumOrange™, TexasRed™ and Cyanine 5 (Cy™5). The ISIS M-FISH imaging system (Metasystems) was used to capture and process images for evaluation of the M-FISH.
A whole genome screening using a high resolution (250 k) Nsp1 SNP-array (Affymetrix, Santa Clara, California, USA) was performed conform manufacturer's specifications. The arrays were scanned using the GeneChip® Scanner 3000 7 G System with autoloader (Affymetrix, Santa Clara, California, USA) and data analysis of the array results was performed using CNAG 3.0 (Copy number analyser for gene chips) provided by http://www.genome.umin.jp. All copy number changes observed were compared to common copy number variants (CNVs) found in previous studies of healthy people annotated in the database of genomic variants (DGV). Common CNVs are variations of large segments (>1 kb) of the genome that occur in the general public and are assumed to have no clinical significance, i.e. are considered benign CNVs. We looked for CNV studies of appreciable size that were analysed with equal methods.
Specific Bacterial Artificial Chromosomes (BAC) probes were selected from the UCSC genome browser (UC Santa Cruz, USA, assembly March 2006)  and the Ensembl genome browser (Hinxton, UK, release 52, Dec 2008)  and purchased from BACPAC Resourses (Oakland, CA, USA) or from BlueGnome (Cambridge, UK) (Table 1). Whole Chromosome Paint (WCP) probes for chromosomes 1, 5, 9, 10, 11, 13, 15 and 18 (Poseidon, NL) were applied on metaphase spreads according to the manufacturer's specifications.
Probe DNA from BACPAC resources was semi-automatically isolated with an AutoGenPrep 3000 robot (Autogen) and, after whole genome amplification (WGA, Repli-G, Qiagen), digested and labelled (Random Prime labelling system, Invitrogen) with Bio-16-dUTP or Dig-11-dUTP (Roche). BlueGnome probes were provided with direct labels. The probes were validated on control metaphases. FISH experiments were performed according to standard protocols, evaluated on an Axioplan 2 Imaging microscope (Zeiss) and images were captured using Isis software (Metasystems).
Written informed consent was obtained from the patients' relatives for publication of this case report. A copy of the written consent is available for review by the Editor-in-Chief of this journal.
The authors thank Sigrid (S.M.A.) Swagemakers of the Department of Bioinformatics of the Erasmus MC for helping to analyse the molecular cytogenetic results in the Ingenuity Pathway Analysis database. Also we want to thank Kamlesh Madan for helpful suggestions and advise.
- Kleczkowska A, Fryns JP, Berghe H: Complex chromosomal rearrangements (CCR) and their genetic consequences. Journal de genetique humaine 1982, 30: 199–214.PubMedGoogle Scholar
- Houge G, Liehr T, Schoumans J, Ness GO, Solland K, Starke H, Claussen U, Stromme P, Akre B, Vermeulen S: Ten years follow up of a boy with a complex chromosomal rearrangement: going from a > 5 to 15-breakpoint CCR. Am J Med Genet A. 2003,118A(3):235–240. 10.1002/ajmg.a.10106PubMedView ArticleGoogle Scholar
- Madan K, Nieuwint AW, van Bever Y: Recombination in a balanced complex translocation of a mother leading to a balanced reciprocal translocation in the child. Review of 60 cases of balanced complex translocations. Human genetics 1997, 99: 806–815. 10.1007/s004390050453PubMedView ArticleGoogle Scholar
- Batista DA, Pai GS, Stetten G: Molecular analysis of a complex chromosomal rearrangement and a review of familial cases. Am J Med Genet 1994, 53: 255–263. 10.1002/ajmg.1320530311PubMedView ArticleGoogle Scholar
- Kausch K, Haaf T, Kohler J, Schmid M: Complex chromosomal rearrangement in a woman with multiple miscarriages. Am J Med Genet 1988, 31: 415–420. 10.1002/ajmg.1320310221PubMedView ArticleGoogle Scholar
- Bartels I, Starke H, Argyriou L, Sauter SM, Zoll B, Liehr T: An exceptional complex chromosomal rearrangement (CCR) with eight breakpoints involving four chromosomes (1;3;9;14) in an azoospermic male with normal phenotype. European journal of medical genetics 2007, 50: 133–138. 10.1016/j.ejmg.2006.10.007PubMedView ArticleGoogle Scholar
- Batanian JR, Eswara MS: De novo apparently balanced complex chromosome rearrangement (CCR) involving chromosomes 4, 18, and 21 in a girl with mental retardation: report and review. Am J Med Genet 1998, 78: 44–51. 10.1002/(SICI)1096-8628(19980616)78:1<44::AID-AJMG9>3.0.CO;2-LPubMedView ArticleGoogle Scholar
- Vermeulen S, Menten B, Van Roy N, Van Limbergen H, De Paepe A, Mortier G, Speleman F: Molecular cytogenetic analysis of complex chromosomal rearrangements in patients with mental retardation and congenital malformations: delineation of 7q21.11 breakpoints. American journal of medical genetics 2004, 124A: 10–18. 10.1002/ajmg.a.20378PubMedView ArticleGoogle Scholar
- Karadeniz N, Mrasek K, Weise A: Further delineation of complex chromosomal rearrangements in fertile male using multicolor banding. Molecular Cytogenetics 2008, 1: 17. 10.1186/1755-8166-1-17PubMed CentralPubMedView ArticleGoogle Scholar
- Tyson C, McGillivray B, Chijiwa C, Rajcan-Separovic E: Elucidation of a cryptic interstitial 7q31.3 deletion in a patient with a language disorder and mild mental retardation by array-CGH. Am J Med Genet A. 2004,129A(3):254–260. 10.1002/ajmg.a.30245PubMedView ArticleGoogle Scholar
- Haj R, Jackson K, Torchia BA, Shaffer LG, Bejjani BA, Gowans GC, Ruff MW: Identification of a rare de novo three-way complex t(5;20;8)(q31;p11.2;p21) with microdeletions on 5q31.2, 5q31.3, and 8p23.2 in a patient with hearing loss and global developmental delay: case report. Molecular Cytogenetics 2009, 2: 2. 10.1186/1755-8166-2-2PubMed CentralPubMedView ArticleGoogle Scholar
- Patsalis PC, Evangelidou P, Charalambous S, Sismani C: Fluorescence in situ hybridization characterization of apparently balanced translocation reveals cryptic complex chromosomal rearrangements with unexpected level of complexity. Eur J Hum Genet 2004, 12: 647–653. 10.1038/sj.ejhg.5201211PubMedView ArticleGoogle Scholar
- Gribble SM, Prigmore E, Burford DC, Porter KM, Ng BL, Douglas EJ, Fiegler H, Carr P, Kalaitzopoulos D, Clegg S, Sandstrom R, Temple IK, Youings SA, Thomas NS, Dennis NR, Jacobs PA, Crolla JA, Carter NP: The complex nature of constitutional de novo apparently balanced translocations in patients presenting with abnormal phenotypes. Journal of medical genetics 2005, 42: 8–16. 10.1136/jmg.2004.024141PubMed CentralPubMedView ArticleGoogle Scholar
- De Gregori M, Ciccone R, Magini P, Pramparo T, Gimelli S, Messa J, Novara F, Vetro A, Rossi E, Maraschio P, et al.: Cryptic deletions are a common finding in "balanced" reciprocal and complex chromosome rearrangements: a study of 59 patients. Journal of medical genetics 2007, 44: 750–762. 10.1136/jmg.2007.052787PubMed CentralPubMedView ArticleGoogle Scholar
- Baptista J, Mercer C, Prigmore E, Gribble SM, Carter NP, Maloney V, Thomas NS, Jacobs PA, Crolla JA: Breakpoint mapping and array CGH in translocations: comparison of a phenotypically normal and an abnormal cohort. American journal of human genetics 2008, 82: 927–936. 10.1016/j.ajhg.2008.02.012PubMed CentralPubMedView ArticleGoogle Scholar
- Goumy C, Mihaescu M, Tchirkov A, Giollant M, Benier C, Francannet C, Jaffray JY, Geneix A, Vago P: De novo balanced complex chromosome rearrangement (CCR) involving chromosome 8, 11 and 16 in a boy with mild developmental delay and psychotic disorder. Genetic counseling (Geneva, Switzerland) 2006, 17: 371–379.Google Scholar
- Schwarzbraun T, Ullmann R, Schubert M, Ledinegg M, Ofner L, Windpassinger C, Wagner K, Kroisel PM, Petek E: Characterization of a de novo complex chromosome rearrangement (CCR) involving chromosomes 2 and 12, associated with mental retardation and impaired speech development. Cytogenetic and genome research 2006, 115: 84–89. 10.1159/000094804PubMedView ArticleGoogle Scholar
- Liehr T, Starke H, Weise A, Lehrer H, Claussen U: Multicolor FISH probe sets and their applications. Histol Histopathol 2004,19(1):229–237.PubMedGoogle Scholar
- Speicher MR, Gwyn Ballard S, Ward DC: Karyotyping human chromosomes by combinatorial multi-fluor FISH. Nature genetics 1996, 12: 368–375. 10.1038/ng0496-368PubMedView ArticleGoogle Scholar
- Solinas-Toldo S, Lampel S, Stilgenbauer S, Nickolenko J, Benner A, Dohner H, Cremer T, Lichter P: Matrix-based comparative genomic hybridization: biochips to screen for genomic imbalances. Genes, chromosomes & cancer 1997, 20: 399–407. 10.1002/(SICI)1098-2264(199712)20:4<399::AID-GCC12>3.0.CO;2-IView ArticleGoogle Scholar
- Pinkel D, Segraves R, Sudar D, Clark S, Poole I, Kowbel D, Collins C, Kuo WL, Chen C, Zhai Y, Dairkee SH, Ljung BM, Gray JW, Albertson DG: High resolution analysis of DNA copy number variation using comparative genomic hybridization to microarrays. Nature genetics 1998, 20: 207–211. 10.1038/2524PubMedView ArticleGoogle Scholar
- Database of Genomic Variants [http://projects.tcag.ca/variation/]
- Shaffer LG, Tommerup N, eds: ISCN (2005): An International System for Human Cytogenetic Nomenclature, S. Karger, Basel. 2005.Google Scholar
- Ingenuity Pathway Analysis database [http://www.ingenuity.com/]
- Schuffenhauer S, Seidel H, Oechsler H, Belohradsky B, Bernsau U, Murken J, Meitinger T: DiGeorge syndrome and partial monosomy 10p: case report and review. Annales de genetique 1995, 38: 162–167.PubMedGoogle Scholar
- Yatsenko SA, Yatsenko AN, Szigeti K, Craigen WJ, Stankiewicz P, Cheung SW, Lupski JR: Interstitial deletion of 10p and atrial septal defect in DiGeorge 2 syndrome. Clinical genetics 2004, 66: 128–136. 10.1111/j.1399-0004.2004.00290.xPubMedView ArticleGoogle Scholar
- Christian SL, Brune CW, Sudi J, Kumar RA, Liu S, Karamohamed S, Badner JA, Matsui S, Conroy J, McQuaid D, Gergel J, Hatchwell E, Gilliam TC, Gershon ES, Nowak NJ, Dobyns WB, Cookjr EH: Novel Submicroscopic Chromosomal Abnormalities Detected in Autism Spectrum Disorder. Biological psychiatry 2008, 63: 1111–1117. 10.1016/j.biopsych.2008.01.009PubMed CentralPubMedView ArticleGoogle Scholar
- Koochek M, Harvard C, Hildebrand MJ, Van Allen M, Wingert H, Mickelson E, Holden JJ, Rajcan-Separovic E, Lewis ME: 15q duplication associated with autism in a multiplex family with a familial cryptic translocation t(14;15)(q11.2;q13.3) detected using array-CGH. Clinical genetics 2006, 69: 124–134. 10.1111/j.1399-0004.2005.00560.xPubMedView ArticleGoogle Scholar
- Verri A, Maraschio P, Devriendt K, Uggetti C, Spadoni E, Haeusler E, Federico A: Chromosome 10p deletion in a patient with hypoparathyroidism, severe mental retardation, autism and basal ganglia calcifications. Annales de genetique 2004, 47: 281–287.PubMedView ArticleGoogle Scholar
- Kumar RA, KaraMohamed S, Sudi J, Conrad DF, Brune C, Badner JA, Gilliam TC, Nowak NJ, Cook EH Jr, Dobyns WB, Christian SL: Recurrent 16p11.2 microdeletions in autism. Human molecular genetics 2008, 17: 628–638. 10.1093/hmg/ddm376PubMedView ArticleGoogle Scholar
- Sismani C, Kitsiou-Tzeli S, Ioannides M, Christodoulou C, Anastasiadou V, Stylianidou G, Papadopoulou E, Kanavakis E, Kosmaidou-Aravidou Z, Patsalis PC: Cryptic genomic imbalances in patients with de novo or familial apparently balanced translocations and abnormal phenotype. Molecular Cytogenetics 2008, 1: 15. 10.1186/1755-8166-1-15PubMed CentralPubMedView ArticleGoogle Scholar
- Lupski JR, Stankiewicz P: Genomic disorders: molecular mechanisms for rearrangements and conveyed phenotypes. PLoS genetics 2005, 1: e49. 10.1371/journal.pgen.0010049PubMed CentralPubMedView ArticleGoogle Scholar
- Velagaleti GV, Bien-Willner GA, Northup JK, Lockhart LH, Hawkins JC, Jalal SM, Withers M, Lupski JR, Stankiewicz P: Position effects due to chromosome breakpoints that map approximately 900 Kb upstream and approximately 1.3 Mb downstream of SOX9 in two patients with campomelic dysplasia. American journal of human genetics 2005, 76: 652–662. 10.1086/429252PubMed CentralPubMedView ArticleGoogle Scholar
- Karpen GH: Position-effect variegation and the new biology of heterochromatin. Current opinion in genetics & development 1994, 4: 281–291. 10.1016/S0959-437X(05)80055-3View ArticleGoogle Scholar
- Kenwrick S, Patterson M, Speer A, Fischbeck K, Davies K: Molecular analysis of the Duchenne muscular dystrophy region using pulsed field gel electrophoresis. Cell 1987, 48: 351–357. 10.1016/0092-8674(87)90438-7PubMedView ArticleGoogle Scholar
- Schouten JP, McElgunn CJ, Waaijer R, Zwijnenburg D, Diepvens F, Pals G: Relative quantification of 40 nucleic acid sequences by multiplex ligation-dependent probe amplification. Nucleic acids research 2002, 30: e57. 10.1093/nar/gnf056PubMed CentralPubMedView ArticleGoogle Scholar
- Iafrate AJ, Feuk L, Rivera MN, Listewnik ML, Donahoe PK, Qi Y, Scherer SW, Lee C: Detection of large-scale variation in the human genome. Nature genetics 2004, 36: 949–951. 10.1038/ng1416PubMedView ArticleGoogle Scholar
- UCSC Genome Bioinformatics [http://genome.ucsc.edu/]
- Ensembl Genome Browser [http://www.ensembl.org/index.html]
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