Structural aberrations of the long arm of chromosome no. 22. Report fo a family with translocation t(11;22) (q25;q11)

A chromosomal translocation t(11;22) (q25q11) is described in a family. Four members, in two generations, had the same translocation but showed phenotypic variation. Case reports of chromosome aberrations involving the long arm of chromosome 22 associated with and without chronic myeloid leukemia (CML) are reviewed. It appears that the distal segment of the long arm or chromosome 22 is either translocated or deleted, resulting in congenital anomalies, presumably due to chromosome imbalance. In other instances, a specific breakpoint on 22q results in the origin of Philadelphia chromosome (Ph1) associated with CML.     

Der(22)t(11;22) resulting from a paternal de novo translocation, adjacent 1 segregation, and maternal heterodisomy of chromosome 22

The t(11;22) (q23;q11) translocation is the most frequently identified familial reciprocal translocation in humans. In translocation carriers, 3:1 meiotic segregation with tertiary trisomy can occur resulting in abnormal progeny with the der(22) as the supernumary chromosome. Affected children have a distinct phenotype with multiple anomalies and severe mental retardation. We have identified a child with developmental delay and multiple anomalies consistent with the der(22) phenotype. Cytogenetic analysis showed an abnormal chromosome complement of 47,XX,+der(22)t(11;22)(q23; q11) in all 50 cells analysed. FISH analysis using chromosome 11 and 22 painting probes showed a pattern consistent with a reciprocal translocation of the distal bands 11q23 and 22q11 respectively. Parental karyotypes were normal. RFLP analysis of locus D22S43, which maps above the t(11;22) breakpoint, showed that the der(22) was paternal in origin and indicated that the normal chromosomes 22 were the probable result of maternal heterodisomy. RFLP analysis of locus D22S94, which maps below the t(11;22) breakpoint, also suggested that both normal chromosomes 22 of the child represented the two maternal homologues. Non-paternity was excluded through the analysis of 10 microsatellite markers distributed on 10 different chromosomes and three VNTRs on three different chromosomes. To the best of our knowledge, this is the first reported case of a patient with an abnormal karyotype resulting from a de novo translocation in the paternal germline with probable unbalanced adjacent 1 segregation and maternal non-disjunction of chromosome 22 in meiosis I.     

Molecular characterization of a variant Ph1 translocation t(9;22;11) (q34;q11;q13) in chronic myelogenous leukemia (CML) reveals the translocation of the 3'-part of BCR gene to the chromosome band 11q13

We performed cloning and sequence analysis of translocation junctions at 11q- and 22q- (Ph1) chromosomes and the corresponding germline DNAs of a variant Ph1-positive CML with t(9;22;11)(q34;q11;q13). Southern blot analysis using probes for different regions of bcr mapped the translocation break near the 5'-side of bcr exon 4. Cloning, Southern blot analysis and restriction map analysis of both bcr fragments showed that the part of bcr 3'- to the translocation break moved to 11q13. Sequence analysis of the translocation junction on the Ph1 chromosome showed that the translocation break occurred 63 bp upstream of exon 4. Compared to the germline sequence, bcr sequence from the translocated partners showed deletion of seven basepairs at the site of translocation. A probe derived from the 5'-region of the clone isolated from the 11q- chromosome identified clonal rearrangements in the leukemic DNA. Restriction map and sequence analysis showed that this clone consisted of the 3'-half of the glutathione S-transferase Pi (GST-Pi) gene and the 3'-part of bcr. We identified two point mutations in the GST-Pi allele involved in translocation. Northern blot analysis showed that the GST-Pi gene was expressed in the leukemic cells at blast crisis but not at chronic phase; however, no fusion mRNA between GST-Pi and bcr was identified. We did not find any sequence homology between 11q13 DNA and 22q11 DNA around the translocation breakpoints; however, sequences homologous to ALU repeats were identified close to the sites of translocation breaks at 22q11 and 11q13. This study supports our hypothesis that variant Ph1 translocations may occur as primary cytogenetic changes similar to the classical Ph1 translocations.     

Application of the planning compass to the nursing curriculum: a tool for health promotion practice

Holoprosencephaly (HPE) is a common developmental defect involving the brain and face. HPE is extremely heterogeneous, some cases being associated with structural anomalies of the short arm of chromosome 3. For a detailed characterization of a t(3;19)(p14.1;p13.1) breakpoint associated with HPE, we performed fluorescence in situ hybridization (FISH) analysis using yeast artificial chromosomes (YACs) mapped to the short arm of chromosome 3 from the Le Centre d'Etude du Polymorphisme Humain (CEPH) library. Three YACs mapped proximal, and one was located distal to the described breakpoint on chromosome 3. One of the chromosome 3 'Mega-YACs' spanned the translocation breakpoint. From this chimeric YAC we generated a site specific probe of about 370 kb by digestion of the YAC-DNA, which will be assessed for gene alterations that could underlie HPE in this patient.     

Ovarian cysts in children and adolescents: their occurrence, behavior, and management

OBJECTIVE: This was a retrospective analysis of cytogenetic data from 600 cases with chronic myelogenous leukemia (CML) to investigate the features of Ph chromosome and its significance. METHODS: Bone marrow direct method and/or short-term culture were used to prepare the chromosomes and karyotype analysis was performed with R-banding technique. RESULTS: 30 cases (5%) were Ph negative; 570 cases (95%) were Ph positive. 535 cases (93.8%) had standard Ph translocation;34 cases(5.9%) had variant translocation, including 13 cases (2.2%) with simple variant translocation, 13 cases (2.2%) with complex variant translocation and 8 cases (1.4%) with masked Ph chromosome. 526 cases (92.2%) had 100% of Ph positive cells; 44 cases (7.7%) had normal karyotype in partial or all metaphases after treatment such as allogeneic bone marrow transplantation, interferon and pulse hydroxyurea therapy, but conventional chemotherapy had no effect on the percentage of Ph positive cells. 50.6% of Ph positive CML with blast crisis had extra chromosomal abnormalities, of which, the most common ones were +8(46.1%),2 Ph(33.9%) and i(17q) (23%) in descending order. CONCLUSION: These facts indicate that chromosome examinations not only help diagnose and differentiate CML,but also help predict the blast crisis, evaluate the therapeutic effect, and make a cytogenetic classification for CML.     

Fusion of the MLL gene with two different genes, AF-6 and AF-5alpha, by a complex translocation involving chromosomes 5, 6, 8 and 11 in infant leukemia

We analysed a complex translocation involving chromosomes 5, 6, 8 and 11 in a case of infant leukemia. Molecular analysis of the MLL gene revealed that MLL was fused with two different genes, AF-6 on chromosome 6q27 and AF-5alpha. AF-5alpha, the 11th partner gene fused with MLL, is a novel gene mapped to chromosome 5q12, which encodes a 31 kDa protein of 269 amino acids and contains a possible nuclear targeting sequence, a potential leucine zipper dimerization motif and an alpha-helical coiled-coil domain. In situ hybridization and molecular cloning analyses demonstrated that two different types of chromosomal recombination had occurred in the cells. One was a three-way translocation among chromosomes 6, 8 and 11, and the other was an insertion of a chromosome 5-derived segment into the breakpoint of chromosomes 8 and 11. Accordingly, the karyotype was defined as del(5)(q11.2q12), der(6)t(6;8) (q27;q11.2), der(8)(8pter-->8q11.2::5q11.2-->5q12::11q23-->++ +11qter), der(11)t(6;11) (q27;q23). Thus, the MLL gene created two different fusion mRNAs, since the chromosome 11 split into two different chromosomes 5 and 6. This is the first report demonstrating fusion of the MLL gene with two different genes by a complex translocation.     

Neuroprotective effect of eliprodil: attenuation of a conditioned freezing deficit induced by traumatic injury of the right parietal cortex in the rat

We report on a familial three way translocation involving chromosomes 3, 6, and 15 identified by prometaphase banding and fluorescence in situ hybridisation (FISH). Two mentally retarded sibs with different phenotypic abnormalities, their phenotypically normal sister and mother, and two fetuses of the phenotypically normal sister were analysed. The terminal regions of chromosomes 3q, 6q, and 15q were involved in a reciprocal translocation, in addition to a paracentric inversion of the derivative chromosome 15. Conventional cytogenetic studies with high resolution GTG banding did not resolve this rearrangement. FISH using whole chromosome paints (WCPs) identified the chromosomal regions involved, except the aberrant region of 3q, which was undetectable with these probes. Investigation of this region with the subtelomeric FISH probe D3S1445/D3S1446 showed a balanced karyotype, 46,XX,t(3;15;6) (q29;q26.1;q26), inv der(15) (q15.1q26.1) in two adult females and one fetus. It was unbalanced in two sibs, showing two different types of unbalanced translocation resulting in partial trisomy 3q in combination with partial monosomy 6q in one patient and partial trisomy 15q with partial monosomy 6q in the other patient and one fetus. These represent apparently new chromosomal phenotypes.     

Common region of ALL-1 gene disrupted in epipodophyllotoxin-related secondary acute myeloid leukemia

Translocations at chromosomal band 11q23 characterize most de novo acute lymphoblastic leukemias (ALL) of infants, acute myeloid leukemias (AML) of infants and young children, and secondary AMLs following epipodophyllotoxin exposure. The chromosomal breakpoints at 11q23 have been cloned from isolated cases of de novo ALL and AML. Using an 859-base pair BamHI fragment of human ALL-1 complementary DNA that recognizes the genomic breakpoint region for de novo ALL and AML, we investigated two cases of secondary AML that followed etoposide-treated primary B-lineage ALL. In the first case, the translocation occurred between chromosomes 9 and 11 and the breakpoint at 11q23 localized to the same 9-kilobase region of the ALL-1 gene that is disrupted in most of the de novo leukemias. In the second case the translocation was between chromosomes 11 and 19. The breakpoint occurred outside of the ALL-1 breakpoint cluster region.     

Predominance of a maternal history of diabetes for patients with non-insulin-dependent diabetes mellitus. Implications for the intrauterine transmission of diabetes

Smith-Lemli-Opitz syndrome (SLOS) is an autosomal recessive disorder characterized by multiple congenital anomalies and mental retardation. SLOS has an associated defect in cholesterol biosynthesis, but the molecular genetic basis of this condition has not yet been elucidated. Previously our group reported a patient with a de novo balanced translocation [t(7;20)(q32.1;q13.2)] fitting the clinical and biochemical profile of SLOS. Employing fluorescence in situ hybridization (FISH), a 1.8 Mb chromosome 7-specific yeast artificial chromosome (YAC) was identified which spanned the translocation breakpoint in the reported patient. The following is an update of the on-going pursuit to physically and genetically map the region further, as well as the establishment of candidate genes in the 7q32.1 breakpoint region.     

Risk factors for serious nonsteroidal-induced gastrointestinal complications: regression analysis of the MUCOSA trial

Gene rearrangements involving MLL (also known as ALL1, HRX, or Htrx) are among the most common molecular abnormalities associated with acute leukemia. These leukemias generally have one allele involved in a rearrangement, while the remaining allele is uninvolved and demonstrates a germline MLL configuration. In this study, we describe a leukemic cell line that does not have a germline MLL allele and thus cannot produce a normal MLL gene product. We show that the ML-1 cell line, derived from a patient with acute myeloid leukemia, has one allele involved in a t(6;11)(q27;q23), while the remaining MLL allele is deleted. Cloning of the genomic breakpoints on the derivative(6) and der(11) chromosomes demonstrated a balanced translocation between MLL on chromosome band 11q23 and AF6 on chromosome band 6q27. Sequence analysis of the derivative chromosomes revealed that a 186-bp segment of MLL intron 6, downstream of the breakpoint, had been duplicated, inverted, and inserted between MLL and AF6 on the der(11) chromosome. In light of the fact that ML-1 cells can be induced to differentiate along the granulocyte and macrophage lineages, the finding that ML-1 lacks a germline MLL allele demonstrates that a normal MLL gene is not required for survival, proliferation, or differentiation of this cell line.     

Chromosomal rearrangements detected by FISH and G-banding

Fluorescence in situ hybridization (FISH) using chromosome-specific DNA libraries as painting probes, locus-specific unique sequence (cosmid) probes, and Y-specific repetitive sequences was applied in the analysis of eighteen cases of chromosomal rearrangements of undetermined nature. FISH clarified the origin of the extra or translocated chromosome segments in seventeen patients, one with 2q+, two with 4q+, one each with 6p+, 7p+, 9q+, 10p+, 11q+ and 12p+, two with 13q+, and one each with 15q+, 17p+, 18p+, 20p+, 21p+ and Yq+, as well as the nature of a de novo supernumerary chromosome marker in a previously reported case. By G-banding and molecular cytogenetic studies of the family members, six cases were determined to have unbalanced translocations inherited from the carrier parent. The extra translocated genetic material may cause specific trisomic syndromes, including partial 6p21.3-p23, 9q32-q34.3, 13q32-q34, 15q24-q26, and 17p11.2-p13 trisomies in those patients. A translocated 21q segment on 12p was shown by a painting probe in a patient with Down features. A patient with cat cry syndrome resulting from a loss of the terminal segment of the short arm of chromosome 5 was confirmed by a cosmid probe showing de novo reciprocal translocation between chromosomes 5 and 18:t(5;18) (p13.3;p11.31). With FISH, the extra material on the rearranged chromosome could also be identified as duplicated or translocated. The FISH technique thus provides a method for the analysis of extra structurally abnormal chromosomes (especially in de novo cases), recognizable syndromes (contiguous gene syndromes) caused by translocated deletion from parental balanced chromosome rearrangements, and supernumerary marker chromosomes. FISH subsequent to G-banding is also of great help in the confirmation of preliminary abnormal G-banded karyotypes after a modified destaining procedure. In conclusion, the combination of G-banding and FISH is very useful in the accurate diagnosis of chromosomal rearrangements.     

Molecular cytogenetic evidence for a common breakpoint in the largest inverted duplications of chromosome 15

Chromosomes from 20 patients were used to delineate the breakpoints of inverted duplications of chromosome 15 (inv dup[15]) that include the Prader-Willi syndrome/Angelman syndrome (PWS/AS) chromosomal region (15q11-q13). YAC and cosmid clones from 15q11-q14 were used for FISH analysis, to detect the presence or absence of material on each inv dup(15). We describe two types of inv dup(15): those that break between D15S12 and D15S24, near the distal boundary of the PWS/AS chromosomal region, and those that share a breakpoint immediately proximal to D15S1010. Among the latter group, no breakpoint heterogeneity could be detected with the available probes, and one YAC (810f11) showed a reduced signal on each inv dup(15), compared with that on normal chromosomes 15. The lack of breakpoint heterogeneity may be the result of a U-type exchange involving particular sequences on either homologous chromosomes or sister chromatids. Parent-of-origin studies revealed that, in all the cases analyzed, the inv dup(15) was maternal in origin.     

Analysis of 1;17 translocation breakpoints in neuroblastoma: implications for mapping of neuroblastoma genes

Deletions and translocations resulting in loss of distal 1p-material are known to occur frequently in advanced neuroblastomas. Fluorescence in situ hybridisation (FISH) showed that 17q was most frequently involved in chromosome 1p translocations. A review of the literature shows that 10 of 27 cell lines carry 1;17 translocations. Similar translocations were also observed in primary tumours. Together with the occurrence of a constitutional 1;17 translocation in a neuroblastoma patient, these observations suggest a particular role for these chromosome re-arrangements in the development of neuroblastoma. Apart from the loss of distal 1p-material, these translocations invariably lead to extra copies of 17q. This also suggested a possible role for genes on 17q in neuroblastoma tumorigenesis. Further support for this hypothesis comes from the observation that in those cell lines without 1;17 translocations, other chromosome 17q translocations were present. These too lead to extra chromosome 17q material. Molecular analysis of 1;17 translocation breakpoints revealed breakpoint heterogeneity both on 1p and 17q, which suggests the involvement of more than 2 single genes on 1p and 17q. The localisation of the different 1p-breakpoints occurring in 1;17 translocations in neuroblastoma are discussed with respect to the recently identified candidate tumor suppressor regions and genes on 1p. In this study, we focused on the molecular analysis of the 17q breakpoints in 1;17 translocations. Detailed physical mapping of the constitutional 17q breakpoint allowed for the construction of a YAC contig covering the breakpoint. Furthermore, a refined position was determined for a number of 17q breakpoints of 1;17 translocations found in neuroblastoma cell lines. The most distal 17q breakpoint was identified in cell line UHG-NP and mapped telomeric to cosmid cCI17-1049 (17q21). This suggests that genes involved in a dosage-dependent manner in the development of neuroblastoma map in the distal segment 17q22-qter. Future studies aim at the molecular cloning of 1;17 translocation breakpoints and at deciphering the mechanisms leading to 1;17 translocations and possibly to the identification of neuroblastoma genes at or in the vicinity of these breakpoints.     

Preimplantation genetic analysis of translocations: case-specific probes for interphase cell analysis

Carriers of balanced translocations show an increased risk of infertility and spontaneous abortions, because of errors in gametogenesis, and constitute a significant fraction of patients seeking assisted reproduction. The objective of this study was to design approaches for preimplantation diagnosis of chromosome translocations and to apply such techniques to the selection of chromosomally normal or balanced embryos prior to their transfer to the mother's womb. Three slightly different approaches were assessed by means of chromosome-specific, non-isotopically labeled DNA probes and an assay based on fluorescence in situ hybridization- to score and characterize chromosomes in single blastomeres biopsied from embryos on their third day of development. The three approaches were used for preimplantation genetic diagnosis involving four couples who had enrolled in our IVF program and in which one of the partners was a carrier of one of the following translocations: 46,XX,t(12;20)(p 13.1 ;q 13.3), 46,XY,t(3;4) (p24;p15), 45,XY,der(14;15)(10q;10q), and 46,XY,t(6;11) (p22.1;p15.3). A total of 33 embryos were analyzed, of which 25 (75.8%) were found to be either unbalanced or otherwise chromosomally abnormal. Only a single embryo could be transferred to patients A and D, whereas three embryos were transferred to patient B in a total of two IVF cycles. Transfer of two embryos to patient C resulted in an ongoing pregnancy. Re-analysis of non-transferred embryos with additional probes confirmed the initial results in 95% (20/21) of the cases. In conclusion, case-specific translocation tests can be applied to any translocation carrier for the selection of normal or chromosomally balanced embryos prior to embryo transfer. This is expected significantly to increase the success rates in IVF cycles of translocation carriers, while preventing the spontaneous abortion or birth of abnormal offspring.     

Unbalanced t(3;12) in a case of juvenile myelomonocytic leukemia (JMML) results in partial trisomy of 3q as defined by FISH

Juvenile myelomonocytic leukemia (JMML) is a rare disorder of early childhood, to which no recurrent chromosome rearrangement has been yet associated. We report a case where leukemic cells harbored a 46,XX,der(12)t(3;12) (q21 approximately 22;p13.33) karyotype, resulting in partial trisomy of 3q. The origin of chromosome material translocated to chromosome 12 was assessed by chromosome painting using a whole chromosome 3-specific probe. The breakpoint regions were defined by FISH using YAC probes from 3q and 12p chromosomal regions. Interestingly, partial trisomy of 3q has been detected in a previously reported JMML case, consequent to the presence of a der(15)t(3;15)(q13.1;q26). The involvement of a similar chromosome 3 rearrangement in these two JMML cases suggests the hypothesis that either the resulting duplication of some gene/s on 3q or the loss of heterozygosity (LOH) of some gene/s on 3p may be involved in one of the steps leading to JMML. On the other hand, it cannot be ruled out that the relevant mutation in our case might be consequent to the particular breakpoints at bands 3q21 approximately 22 and 12p13.3, that may alter the structure and/or expression of the involved gene/s.