TPA stimulation culture for improved detection of t(11;14)(q13;q32) in mantle cell lymphoma

Cytogenetic analysis of mantle cell lymphoma (MCL), characterized by the presence of t(11;14)(q13;q32) translocation, is often difficult because of the low proliferating rate of MCL cells and the presence of normal cells in bone marrow which may interfere with growth of MCL cells. We describe herein a TPA (12-O-tetradecanoylphorbol 13-acetate) stimulated culture to improve detection of t(11;14)(q13;q32) in 20 MCL patients regardless of the samples used.     

Meiotic and sperm chromosome studies in a reciprocal translocation t(1;2)(q32;q36)

Summary Meiotic and sperm chromosomes were studied in a man heterozygous for a reciprocal translocation t(1;2)(q32; q36). Forty-five meiotic metaphase I cells were obtained from semen samples: 86.6% were 22,XY,IV and 13.3% had synaptic anomalies that affected all or some of the bivalents. The quadrivalents observed had a ring configuration (92.3%) or a chain configuration (7.7%). A total of 105 sperm chromosome complements were analyzed: 41% resulted from an alternate segregation, and the percentage of unbalanced sperm was 59%; most of them (71%) resulted from an adjacent 1 segregation. The frequency of anomalies unrelated to the translocation (5.7% numerical and 14.1% structural anomalies) were within the normal range for control donors. There was a good correspondence between the percentage of cells with a ring IV (92.3%) and the proportion of 2:2 segregations (88.6%) and between the percentage of chain IV (7.7%) and the incidence of 3:1 segregations (11.4%).     

A subpopulation of t(2;14)(p11;q32) cells in ataxia telangiectasia B lymphocytes

Summary Partially purified B cells from ataxia telangiectasia (A-T) patients and normal individuals were stimulated with Staphylococcus aureus Cowan I organisms (SAC). High levels of apparently random rearrangements were seen in the A-T B cells only. In addition a t(2;14)(p11;q32) rearrangement was identified in B cells from more than one patient.     

Fine mapping of the constitutional translocation t(11;22)(q23;q11)

Translocation t(11;22)(q23;q11) is the most common constitutional reciprocal translocation in man. Balanced carriers are phenotypically normal, except for decreased fertility, an increased spontaneous abortion rate and a possible predisposition to breast cancer in some families. Here, we report the high resolution mapping of the t(11;22)(q23;q11) breakpoint. We have localised the breakpoint, by using fluorescence in situ hybidisation (FISH) walking, to a region between D11S1340 and WI-8564 on chromosome 11, and D22S134 and D22S264 on chromosome 22. We report the isolation of a bacterial artificial chromosome (BAC) clone spanning the breakpoint in 11q23. We have narrowed down the breakpoint to an 80-kb sequenced region on chromosome 11 and FISH analysis has revealed a variation of the breakpoint position between patients. In 22q11, we have sequenced two BACs (BAC2280L11 and BAC41C4) apparently mapping to the region; these contain low copy repeats (LCRs). Southern blot analysis with probes from BAC2280L11 has revealed different patterns between normal controls and translocation carriers, indicating that sequences similar/identical to these probes flank the translocation breakpoint. The occurrence of LCRs has previously been associated with genomic instability and "unclonable" regions. Hence, the presence of such repeats renders standard translocation breakpoint cloning techniques ineffective. Thus, we have used high resolution fiber-FISH to study this region in normal and translocation cases by using probes from 22q11, LCRs and 11q23. We demonstrate that the LCR containing the gap in 22q11 is probably substantially larger than the previous estimates of 100 kb. Using fiber-FISH, we have localised the breakpoint in 22q11 to approximately 20-40 kb from the centromeric border of the LCR (i.e. the telomeric end of AC006547) and have confirmed the breakpoint position on 11q23.     

Unbalanced 1q whole-arm translocation resulting in der(14)t(1;14)(q11-12;p11) in myelodysplastic syndrome

Unbalanced whole-arm translocations (WATs) of the long arm of chromosome 1, resulting in complete trisomy 1q, are chromosomal abnormalities detectable in both solid tumors and hematologic neoplasms. Among the WATs of 1q to acrocentric chromosomes, a few patients with der(1;15) described as a dicentric chromosome have been reported so far, whereas cases of der(1;14) are much rarer. We report on a case of der(1;14) detected as single anomaly in a patient with myelodysplastic syndrome. The aim of our work was to investigate the breakpoints of the (1;14) translocation leading to the der(1;14). Fluorescence in situ hybridization (FISH) experiments have been performed on chromosome preparations from bone marrow aspirate, using specific centromeric probes of both chromosomes, as well as a probe mapping to 1q11 band. FISH results showed that in our patient the derivative chromosome was monocentric with a unique centromere derived from chromosome 14. The breakpoints of the translocation were located in the short arm of chromosome 14 and in the long arm of chromosome 1, between the alphoid D1Z5 and the satellite II domains. The 1q breakpoint was within the pericentromeric region of chromosome 1, which is notoriously an unstable chromosomal region, involved in different chromosomal rearrangements.     

Familial aniridia and translocation t(4;11)(q22;p13) without Wilms' tumor

A family with dominantly inherited aniridia in three generations is presented. All three patients had an apparently balanced chromosome translocation t(4;11)(q22;p13). The patients were otherwise clinically normal and without signs of Wilms' tumor; their erythrocyte catalase activities were within the normal range. We suggest that in this family aniridia is caused either by a submicroscopic deletion at the translocation breakpoint 11p13 or by a position effect on the same chromosome segment. Furthermore, the loci for aniridia and Wilms' tumor susceptibility are separate. It follows that the WAGR complex is caused by a mutation of more than one gene located at 11p13. The theoretical implications of a presumably defective allele causing a mendelian dominant phenotype are discussed.     

The position of t(11;22)(q23;q11) constitutional translocation breakpoint is conserved among its carriers

The t(11;22)(q23;q11) translocation is the most common recurrent balanced translocation described in humans. Carriers are phenotypically normal and often go undetected until diagnosis as a result of infertility investigations or following the birth of chromosomally unbalanced offspring. Efficient diagnostics of t(11;22) is important for children born to carriers of the translocation and for prenatal and pre-implantation diagnosis. The translocation breakpoint on chromosome 22 is located within a region containing low copy repeats, and this site is one of the last unfilled gaps in the sequence of this chromosome. This autosome harbors multiple other low copy repeats, which have been entirely sequenced. We report a combined sequencing and fiber FISH breakpoint characterization in five translocation carriers. From one carrier a cosmid library was constructed, and two chimeric cosmids (cos4_der11 and cos6_der22) were sequenced, which showed that strong palindromes (or inverted repeats) occur on both chromosomes. The translocation breakpoints occur at the tip of both inverted repeats. The palindrome on chromosomes 22 and 11 is composed of 852 and 166 bases, respectively. Four additional carriers were studied using fiber FISH with a resolution limit of 2 kb. Analysis of breakpoints on the DNA sequence level, or at the level of fiber FISH, indicate that they occur at the same position on both chromosomes in all five carriers. Using cos6_der22, PAC 158L19 and BAC 3009A19, we demonstrate that FISH is an attractive alternative in molecular diagnostics of t(11;22), as PCR assays are not reliable, due to the presence of numerous copies of low copy repeats.     

Meiotic chromosome segregation in human t(11;22)(q23;q11) carriers: a theoretical consideration

The t(11;22)(q23;q11) translocation is the most frequently encountered familial reciprocal translocation in humans. In the majority of reported cases ascertainment has been through the birth of a child with the chromosomal constitution 47,XX,+der(22) or 47,XY,+der(22), i.e., tertiary trisomy. Previous segregation analysis of familial cases showed a number of interesting features. Thus, euploid unbalanced genotypes resulting from adjacent segregation are absent in the progeny, and only tertiary trisomic offspring are recovered. To explain this unusual progeny output we present here a model for the meiotic behavior of this translocation in the carriers based on an analysis of cytogenetic data of progeny of carriers. This model predicts the formation of a chain trivalent with chromosome order 11-der(11)-22 during prophase I and its predominant alternate orientation at metaphase I.     

A t(13q14q) family with the translocation and a Philadelphia chromosome in one member

Summary A family with a t(13q14q) is presented. The leukemic proband had a Philadelphia (Ph¹) chromosome and the translocated chromosome. The translocation seems to have been present in 4 generations.     

Molecular analysis of a reciprocal translocation t(5;11)(q11;p13) in a WAGR patient

Summary Most patients with the complex association aniridia — predisposition to Wilms' tumor (WAGR syndrome) present with a de novo constitutional deletion of band 11p13. We report a patient with WAGR syndrome and a reciprocal translocation between chromosomes 5 and 11 t(5;11)(q11;p13). High resolution banding cytogenetic analysis and molecular characterization using 11p13 DNA markers showed a tiny deletion encompassing the gene for CAT but sparing the gene for FSHB. This suggests that syndromes associated with apparently balanced translocations may be due to undetectable loss of material at the breakpoint(s) rather than to breakage in the gene itself.     

Paternal reciprocal translocation t(11;16)(p13;q24.3) in a Silver-Russel syndrome patient

We describe a 7-month-old male child with Silver-Russel syndrome (SRS) phenotype, presented with two major clinical features: low birth weight, short stature, and minor features, such as macrocephaly, clinodactyly, essential for the diagnosis of SRS. Routine cytogenetic studies with GTG-banding showed 46,XY,t(11;16)(p13;q24.3). Fluorescence in situ hybridisation (FISH) with single copy probes BAC (11p13) and PAC (16q24.3), showed a reciprocal translocation. Chromosomal analysis of the mother was normal and the phenotypically normal father had apparently identical translocation t(11;16)(p13;q24.3). The disruption of growth factor genes at 11p and 16q breakpoint regions due to reciprocal translocation in the father might have caused SRS phenotype in the child.     

Molecular analysis of a t(7;14)(q35;q32) chromosome translocation in a T cell leukemia of a patient with ataxia telangiectasia

Molecular analysis of somatic cell hybrids derived from T cells carrying a t(7;14)(q35;q32) chromosomal translocation from a patient with ataxia telangiectasia and T cell leukemia indicates that the breakpoint on chromosome 14 is proximal to the IgH locus and to the D14S1 locus, while the breakpoint on chromosome 7 involves the T cell receptor beta chain locus immediately 5' to J beta 1.5 on chromosome 7. The separation of V beta and C beta observed in somatic cell hybrids defined the orientation of the T cell receptor beta chain locus on chromosome 7 where the V beta genes are centromeric and the C beta genes are telomeric. A novel chromosomal alteration, undetected cytogenetically, was revealed as being an inversion with duplication of the distal band of chromosome 14q32. The importance of the 14q32 region in the leukemogenic process is discussed.     

Studies of the meiotic behavior of a translocation t(10;13)(q25;q11) in an oligospermic man

Summary An new type of translocation, t(10;13)(q25;q11), is observed in a phenotypically normal male who was examined for subfertility. The meiotic behavior of the rearranged chromosomes indicates that crossing-over is very frequent in a rather small segment such as the short arm of chromosome 13 and constant in the distal band of the long arm of chromosome 10.     

47,XY,+der(11;22)(q23;q12) following balanced translocation t(11;22)(q23;q12)mat

Summary Report of a supernumerary extra chromosome der(11;22)(q23; q12) resulting from a balanced translocation in the mother. The propositus suffers from mental deficiency, deafness and extreme muscular weakness and exhibits cleft palate, a labial lymphangioma and an atrial septum defect. Since the features of partial trisomy 11q23 frequently associated with a translocation t(11q;22q) bear similarities with the cases of so called trisomy 22 one might conjecture that some of these observations are in fact products of translocations including partial 11q.     

A balanced translocation t(11;16)(q13;p11), a cytogenetic study and an attempt at gene localization

Summary Members of three generations of a single family were examined and found to have a balanced translocation t(11;16)(q13;p11). Cytogenetic investigation and investigation of a number of gene markers is consistent with the current view that the Hp- locus is situated in the proximity of band 16q22.     

An azoospermic male with reciprocal translocation t(1;15)(q11;p11)

Summary The authors report on a case of 1;15 translocation and request contact with any colleagues who have observed similar cases.