Subtelomeric rearrangements in idiopathic mental retardation

Objective : To estimate the frequency of subtelomeric rearrangements in patients with sporadic and non-syndromic idiopathic mental retardation (IMR).Methods: A total of 18 IMR patients were taken for the study. Selection criteria included no known syndromes or chromosomes abnormalities and known causes of IMR. All patients signed an informed consent to participate. Chromosome analysis was carried out on all patients to rule out gross chromosome abnormalities. Lymphocyte cultures were initiated and harvested using standard protocols. For fluorescencein situ hybridization (FISH), Chromoprobe Multiprobe-T system was used. this system consists of 24 embossed areas with each area having one reversibly bound subtelomere probe for a specific chromosome. the subtelomere probes were differentially labeled with green fluorescence for short arm and orange for the long arm. Hybridization, washing and staining are done using standard protocols. A minimum of 5 metaphases were analyzed per chromosome per patient.Results : A total of 2 subtelomeric rearrangements were detected (11.1%). Case 1 involved a 17-year-old with severe MR, profound deafness and dysmorphic features with reciprocal translocation t(3;7)(q26.2; p15.1). the second case involved a 4.6-year-old with mild developmental delay and a terminal deletion of the long arm of chromosome 2, del(2) (q37.3). the frequency of abnormalities detected in our study is in agreement with published reports.Conclusion : Subtelomeric screening with FISH is a useful tool for investigation of IMR, however, it is not cost effective in all cases. Conventional chromosome analysis coupled with targeted FISH testing might be the optimal strategy for investigation of IMR.     

DOR-1, A novel CD10+ stromal cell line derived from progressive Langerhans cell histiocytosis of bone

BACKGROUND: Langerhans cell histiocytosis (LCH) is granulomatous proliferative disorder characterized by the presence of activated Langerhans cells admixed with macrophages, lymphocytes, and eosinophils. In an effort to obtain an LCH ex vivo model, we succeeded in establishing the DOR-1 cell line from an LCH lesion of bone in a 3-year-old girl. PROCEDURE: The DOR-1 cell line was established from a CD1a immunoreactive LCH lesion of bone maintained in long-term cell culture. The phenotypic characteristics were assessed by immuno-cytochemistry and fluorescence activated cell sorter (FACS) analysis. Cytogenetic analysis was performed by RHG-banding that was supplemented by fluorescence in situ hybridization (FISH). RESULTS: The DOR-1 cells grew in vitro as a poorly differentiated mesenchymal-like cells with a doubling time between 72 and 96 hr. The cells exhibited pleomorphism and consistent immuno-reactivity for CD10 (50%), CD13 (55%), CD68 (65%), and CD117 (70%) while CD1a, Langerin and HLA-DR were not detected. By RHG-banding, several aberrant chromosomes were detected including the t (9; 17) (p23; p13) translocation and a pair of long dicentric marker chromosomes indicating clonal abnormality. Functionally, exposure to 33 nM 12-O-tetradecanoyl phorbol mirystate-13-acetate (TPA) induced DOR-1 cell differentiation with appearance of cytoplasmic extensions. CONCLUSIONS: The DOR-1 cell line exhibits distinct immuno-cytochemical features and carries the t (9; 17) (p23; p13) translocation suggesting involvement of stromal-like cell lineage in LCH initiation and progression.     

Atypical cat eye syndrome. Fluorescence in situ hybridization of metaphase chromosomes]

In 1983, a chromosome analysis was carried out in a newborn preterm infant with minor anomalies (preauricular skin tag, maldescensus testis). All analysed metaphases showed a small extra chromosome, which was symmetric, dicentric and bi-satellited. In spite of in depth analysis, its origin remained obscure. Recent re-evaluation using fluorescence in situ hybridization (FISH) led to the diagnosis of a dicentric chromosome 22. The FISH technique is an important new tool in chromosome diagnostics. The phenotype of this infant only vaguely resembles the cat eye syndrome. The syndrome should be diagnosed clinically and not only based on the results of chromosome analysis.     

Interphase cytogenetic study of childhood acute lymphoblastic leukemia

We used the fluorescence in situ hybridization (FISH) technique and centromere-specific probes for chromosomes 1, 6, 8, 10, 12, 17, 18, X, and Y to investigate the presence and number of the respective chromosomes in interphase nuclei of 14 cases of childhood acute lymphoblastic leukemia (ALL) which were shown to be hyperdiploid by DNA flow cytometry irrespective of their cytogenetic pattern. Numerical anomalies for one or more chromosomes were detected in all 14 cases. The FISH results were compared with those obtained by conventional cytogenetic analysis. A hyperdiploid karyotype was evident in 5 cases, the others were either normal or lacking cytogenetic results because of technical failure. In the 5 cytogenetically hyperdiploid cases, 14 numerical abnormalities were observed with both techniques, whereas 4 numerical deviations were found only with FISH. In 9 other cases which had a DNA content indicating hyperdiploidy, 34 trisomies and 2 tetrasomies were detected by FISH analysis. Furthermore, in 1 case duplication of the Y chromosome and in 3 male cases duplication of the X chromosome were evident. Double-target FISH experiments in 2 patients allowed the correlation of numerical aberrations of 2 chromosomes in one and the same cell. By such analyses, detection of subpopulations of tumor cells was found to be relatively easy. Our results indicate that the FISH technique with chromosome-specific repetitive centromeric probes is a rapid, simple to use, and easy to interpret technique for the evaluation of numerical chromosomal aberrations in interphase nuclei of leukemias. © 1994 Wiley-Liss, Inc.     

Familial small supernumerary marker chromosome (sSMC) (14)(:P11–q11:)In a child with translocation down syndrome

We report a case of familial small supernumerary marker chromosome (sSMC)in a child with translocation Down syndrome (DS)and mother. The GTG-banded chromosomal analysis of DS child revealed 47,XY,+21,+mar and mother karyotype was 47,XX,+mar. The GTG-banded sSMC had a similar morphology of small acrocentric chromosomes. Fluorescence in situ hybridization (FISH)evaluation of sSMC using centromere probes(13/21,14/22,22)confirmed sSMC as derivative chromosome 14. The sSMC was not specifically stained with whole chromosome paint and arm-specific probes for chromosome 14;thus it has been described as der(14)(:p11–q11:).The phenotypic changes were not evident, may be due to trisomy condition in the child or the sSMC contain repetitive sequences.     

Sirenomelia with a de novo balanced translocation 46,X,t(X;16)(p11.23;p12.3)

We report a female fetus with sirenomelia with 46,X,t(X;16)(p11.23;p12.3) de novo. Fluorescence in situ hybridization (FISH) with bacterial artificial chromosomes were employed for narrowing down the breakpoint regions. On chromosome 16, the breakpoint was mapped in the region of RP11‐453F10 (19 920 640–20 118 153 bp from 16pter). On chromosome X, the breakpoint was mapped in the region of RP11‐794A15 (47 333 744–47 524 066 bp from Xpter). This is the first case report of sirenomelia associated with translocations. The abnormal phenotype, associated with a balanced translocation, was caused by deletion or breakage of dosage‐sensitive genes of the breakpoint, disruption of an imprinted gene, or uniparental disomy. Although the parental origin of normal 16 and der(16) remained undetermined, this case will provide insight into the pathogenetic mechanism of sirenomelia.     

Detection of Trisomy 18 on Formalin-fixed and Paraffin-embedded Material by Fluorescence In Situ Hybridization

Formalin-fixed and paraffin-embedded autopsy material from 10 fetuses and infants with unknown karyotype and anomalies suggestive of trisomy 18 were subjected to fluorescence in situ hybridization (FISH). Nuclei were extracted from the tissues and hybridized with a chromosome 18–specific centromere probe. The hybridization was successful in 9 of 10 cases. Two cases showed three hybridization signals in most of the nuclei (74% and 85%). These had anomalies frequently occurring with trisomy 18 (congenital heart defect, omphalocele, and horseshoe kidney). Two cases showed a mixture of two and three signals (47%/49% and 59%/36%), suggesting the possibility of mosaicism. One of these cases had anomalies consistent with a trisomy 18 phenotype. In the other case intrauterine growth retardation and syndactylies suggested triploidy. Hybridization with a chromosome 8–specific probe gave a distribution of two and three signals (34% and 62%, respectively). This result strengthened the suspicion of a possible triploid mosaicism. In five of the cases most of the nuclei showed two signals (85% to 88%). However, as only one type of tissue was examined for enumeration of chromosome 18, the possibility of organ mosaicism or other chromosome aberrations cannot be excluded. The FISH technique is applicable on macerated and autolysed formalin-fixed tissue, making it possible to retrospectively analyze autopsy material from aborted and stillborn fetuses and infants. This analysis contributes to a better quality of perinatal autopsies and is helpful in parental counseling. Received March 29, 1999; accepted August 17, 1999.     

A del(X)(p11) carrying SRY sequences in an infant with ambiguous genitalia

Background  

SRY (sex-determining region, Y) is the gene responsible of gonadal differentiation in the male and it is essential for the regular development of male genitalia. Translocations involving the human sex chromosomes are rarely reported, however here we are reporting a very rare translocation of SRY gene to the q -arm of a deleted X chromosome. This finding was confirmed by cytogenetic, fluorescent in situ hybridization (FISH) and polymerase chain reaction (PCR).     

1p36 deletion syndrome associated with Prader–Willi‐like phenotype

Background: 1p36 deletion syndrome is one of the most common subtelomeric deletion syndromes, characterized by moderate to severe mental retardation, characteristic facial appearance, hypotonia, obesity, and seizures. The clinical features often overlap with those of Prader–Willi syndrome (PWS). To elucidate the phenotype–genotype correlation in 1p36 deletion syndrome, two cases involving a PWS‐like phenotype were analyzed on molecular cytogenetics. Methods: Two patients presenting with the PWS‐like phenotype but having negative results for PWS underwent fluorescence in situ hybridization (FISH). The size of the chromosome 1p36 deletions was characterized using probes of BAC clones based on the University of California, Santa Cruz (UCSC) Genome Browser. Results: PWS was excluded on FISH and methylation‐specific polymerase chain reaction. Subsequent FISH using the probe D1Z2 showed deletion of the 1p36.3 region, confirming the diagnosis of 1p36 deletion syndrome. Further analysis characterized the 1p36 deletions as being located between 4.17 and 4.36 Mb in patient 1 and between 4.89 and 6.09 Mb in patient 2. Conclusion: Patients with 1p36 deletion syndrome exhibit a PWS‐like phenotype and are therefore probably underdiagnosed. The possible involvement of the terminal 4 Mb region of chromosome 1p36 in the PWS‐like phenotype is hypothesized.     

Trisomy of 8q22.3 approximately q23-qter following an unbalanced 1;8 translocation in a boy with multiple anomalies

An 11-month-old boy was first referred with global developmental delay, pallor and heart defects (ASD, VSD, mitral and tricuspid valve insufficiency). He also had facial abnormalities. Standard karyotyping showed additional material on one chromosome 1p homolog, and fluorescence in situ hybridization (FISH) indicated an unbalanced translocation of 1pter approximately p36.33 and 8q22.3 approximately q23. The breakpoint on p was found to reside very close to the telomere, making this a rare case of "almost pure" trisomy of 8q22.3 approximately q23-qter, without a significant partial 1p36 monosomy by FISH technique. The patient's face resembled the peculiar face in previously reported cases of 8q23-qter duplication. This report supports that critical gene(s) for cardiac septum formation reside on distal chromosome 8q.     

A Case of 4p Trisomy Syndrome Originated from Maternal rcp(4; | 4)(p | 5. |;p ||.|): An Analysis with CBG, Ag-NORs and Cd Banding Techniques in Prometaphase Cells

Abstract A case of 4p trisomy syndrome originated from familial rep (4; 14) is reported. The rearrangement was characterized by a breakpoint at the centromeric region of chromosome 14 and by a reciprocal translocation between chromosomes 4 and 14. The translocation was observed in three generations. As a result of CBG banding analysis in prometaphase cells, the breakpoint of der(14) was considered to be located at 14p11.1, and a part of 14p11.1 was translocated to chromosome 4p. It was unknown whether a part of the centromere was involved in it or not.     

Clinical manifestation of chromosome 2 long arm terminal deletion--presentation of four cases

Terminal deletion of the long arm of chromosome 2 belongs to the most common structural aberrations of subtelomeric chromosomal regions. Clinical manifestations of this syndrome comprise: global psychomotor delay, moderate to severe mental retardation with specific facial dysmorphism. In some cases a phenotype similar to Albright's hereditary osteodystrophy (AHO) may also be observed (short stature, obesity, brachydactyly). The paper covers the characteristics of clinical features in four cases of terminal deletions in 2q36.2, 2q37.1 and 2q37.3 identified in routine cytogenetic study and fluorescent in situ hybridization (FISH) technique. In one case the deletion of subtelomeric region of chromosome 2 (2q37.3) occurred as a result of reciprocal translocation between chromosomes 2 and 7. A comparison was made of clinical symptoms present in our patients with relevant data concerning other cases of 2q monosomy, described in specialized publications.     

1750例遗传咨询儿童细胞遗传学研究

目的探讨遗传咨询儿童染色体核型情况,研究染色体异常与疾病的关系。方法对1 750名遗传咨询儿童进行外周血染色体核型分析。用多重连接探针扩增技术(MLPA)检测染色体的亚端粒,确定小标记染色体(SMCs)的来源。结果共检出异常核型242例,异常率13.8%。常染色体数目异常181例,占异常核型的74.8%;常染色体结构异常28例,占11.6%;性染色体异常22例,占9.1%;染色体多态性11例,占4.5%。发现1例45,XX,psu dic(11;9)(p15;p24)核型,该核型为世界首次报道。结论染色体异常是导致儿童生长发育迟缓、智力低下和性分化异常等疾病的重要原因之一,常规染色体检查,可为临床诊断和治疗提供科学依据。     

Partial monosomy of 10p and duplication of another chromosome in two patients

Partial monosomy of 10p is a rare chromosomal abnormality. Common features are hypoparathyroidism, deafness, renal anomalies, distinctive facies, and mental retardation, with phenotypic variability. We report two patients with chromosomal abnormalities identified on single‐nucleotide polymorphism (SNP) array analysis. Although patient 1 had common features of monosomy10p, G‐banding indicated a normal karyotype. SNP array and fluorescence in situ hybridization (FISH), however, indicated unbalanced translocation of a 10p terminal deletion of 11.7 Mb and a 15q terminal duplication of 8.2 Mb. In patient 2, SNP array and FISH indicated a 10p terminal deletion of 12.6 Mb and a 7q terminal duplication of 1.9 Mb. This is the first case report of monosomy 10p combined with trisomy 15q (patient 1). Because the clinical heterogeneity of the 10p deletion syndrome would be affected by duplication of another chromosome, we emphasize that SNP/microarray analysis is necessary to confirm genotype–phenotype correlation.     

Retrospective analysis of clonality and detection of residual disease in myeloid leukemia by FISH on long-term stored bone marrow smears

Abstract Background. Fluorescence in situ hybridization (FISH) has allowed the detection of numerical chromosomal aberrations in interphase nuclei on fresh or frozen smears of leukemia.
Methods. To analyze clonality and residual disease in myeloid leukemia retrospectively, we applied FISH to bone marrow smears stored at ambient temperature for up to 9 years.
Results: When hybridization efficiency was investigated on stored control smears from patients without hematological malignancy, more than 96% of nuclei showed the expected number of signals using DNA probes specific for chromosome 7, X or Y. In combination with cell morphology, we observed much higher hybridization efficiency in blasts and granulomonocytic cells compared with lymphoid and erythroid cells. On the basis of good hybridization efficiency for old smear specimens, we applied FISH to stored bone marrow smears of myeloid leukemias, in which either loss of chromosome 7 or loss of sex chromosomes had been verified previously by conventional cytogenetics (one patient with chronic myelomonocytic leukemia (CMML) and four with acute myeloid leukemia (AML; three M2 and one M7)). As a result, the loss of chromosome was detected in blasts from all patients and was observed in mature granulocytes, except in M7. In the CMML patient and one AML (M2) patient with t(8;21), lymphoid and erythroid cells also showed the loss of chromosomes, suggesting that it should occur at stem-cell level. A high amount of residual disease was detected in the morphological remission samples in one AML (M2) patient after induction therapy. The patient eventually succumbed to relapse.
Conclusion Thus, the present FISH technique is useful to analyze the clinical significance of clonality and the residual disease in myeloid leukemia, retrospectively.     

A RE-INVESTIGATION OF AN INHERITED CHROMOSOME ABERRATION IN A GIRL WITH SIGNS OF DE LANGE SYNDROME

ABSTRACT. Eeg-Olofsson, O. and Liedgren, S. (Departments of Paediatrics and Gynaecology and Obstetrics, University Hospital, Linköping, Sweden). A re-investigation of an inherited chromosome aberration in a girl with signs of de Lange syndrome. Acta Paediatr Scand, 70:575,.–An earlier report in this journal (1968) dealt with an inherited chromosome aberration in a girl with signs of de Lange syndrome and her family. A translocation between a 13–15 and a 4–5 chromosome, with the unbalanced proposita having an additional segment from one end of a 13–15 chromosome was found. A 6–12 chromosome involvement could not be excluded. The mother and two phenotypically normal sisters had a balanced karyotype. With modern technique a more complex translocation has been found. A part of one chromosome no. 5 is translocated to one chromosome no. 9, a fragment of this chromosome is probably translocated to one chromosome no. 13, and a part of this one is translocated to the first-mentioned chromosome no. 5. The mother and sisters have this balanced chromosomal aberration. The proposita in addition has two normal chromosomes no. 13. Thus she has a partial trisomy of chromosome no. 13. Reinvestigation of older reports on chromosomal aberrations in risk families in order to achieve a more reliable diagnosis in phenotypically normal members of the same family is emphasized.     

Miller‐Dieker Syndrome with unbalanced translocation 45, X,psu dic(17;Y)(p13;p11.32) detected by fluorescence in situ hybridization and G‐banding analysis using high resolution banding technique

Lissencephaly is one of the central nervous system anomalies of Miller‐Dieker Syndrome (MDS). Fetuses with lissencephaly have an abnormal smooth brain with fewer folds and grooves that will be detected by ultrasounds or fetal magnetic resonance imaging (MRI) after 30 weeks of gestation. We report a fetus with lissencephaly diagnosed as Miller‐Dieker Syndrome postnatally. G banded chromosome analysis revealed 45,X,psu dic(17;Y)(p13;p11.32).ish dic (17;Y)(LIS1‐,RARA+, SRY+, DYZ3+) by G‐banding analysis using high resolution banding technique. Fetal delayed cortical development will be the findings to perform further investigations including fluorescence in situ hybridization analysis for MDS, a 17p13.3 microdeletion syndrome, pre/postnatally. This will be the first case of MDS with unbalanced translocation between deleted short arm of chromosome 17 and Y chromosome.     

Characterization of karyotypic events and evolution in neuroblastoma

BACKGROUND: Neuroblastoma (NB) is cytogenetically characterized by a number of non-random events. However, knowledge is limited concerning the timing of occurrence and inter-action of many of these events. METHODS: Karyotypic patterns were obtained from a study group of 49 NB tumors that had been analyzed by conventional cytogenetics combined with FISH and in some instances SKY. RESULTS: All chromosomes were involved in a numerical and structural aberration in at least one tumor. There was a positive correlation between the occurrence of MYCN and del(1p) and between del(1p) and 17q. Aberrations involving chromosomes X, 3, 19, and del(1p) could be considered early events, whereas those involving chromosomes 9, 13, 15, 18, 20, and 21 were often late events. CONCLUSIONS: This study suggests that the karyotypic patterns characterizing NB are complex. There are aberrations that can be grouped into early or late karyotypic events, but others, such as gain of 17q, are variable.