Prenatal diagnosis of supernumerary chromosome derivative (22) due to maternal balanced translocation in association with diaphragmatic hernia: a case report

An aneuploid fetus was detected prenatally by cordocentesis at 27 weeks' gestation following ultrasonographic diagnosis of severe fetal growth retardation and a large diaphragmatic hernia. The fetal karyotype was revealed to be 47,XX,der(22)t(11;22)(q23.3;q11.2) after parental bloods confirmed a balanced reciprocal translocation in the mother. Approximately 85 cases with an unbalanced karyotype 47,XX(or XY),+der(22),t(11;22) due to 3:1 meiotic disjunction in the parental translocation carrier have been reported in the world literature and only one of them was diagnosed prenatally. This is the first detailed case report of a supernumerary derivative (22) chromosome abnormality diagnosed prenatally in association with diaphragmatic hernia.     

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.     

Translocation (13; 18) (q22; p 11) and prenatal diagnosis (author's transl)

A balanced translocation (13; 18) (q 22; p 11) was diagnosed in two generations. Out of 10 pregnancies in these two translocation carriers, mother and daughter, only two phenotypically normal childern were born. One of these, namely the daughter, showed balanced translocation, whilst a normal karyotype was diagnosed prenatally in the second case. The other eight pregnancies ended either in spontaneous abortions, in intrauterine death or in lethal malformations. In the present translocation the formation of unbalanced gametes seems to be enhanced.     

Susceptibility to vinblastine-induced aneuploidy and preferential chromosome segregation during meiosis I in Robertsonian heterozygous mice

Chromosome segregation at meiosis I was studied in oocytes and spermatocytes of four different Robertsonian (Rb) heterozygous mouse stocks by cytogenetic analysis of meiotic products. Two Rb heterozygotes spontaneously yielded high frequencies of unbalanced oocytes. In one case, Rb(2.18)Rma, the excess hyperploidy was mainly accounted for by nondisjunction of normal bivalents, suggesting a generalized impairment of meiotic segregation. In each stock, frequencies of hyperploid spermatocytes were either not significantly different or significantly lower than the corresponding frequencies in the oocytes. This confirmed the greater risk of segregational errors in female than in male carriers of the same Rb metacentric. The hypothesis that an error prone system of meiotic segregation, such as the trivalent configuration of single Rb heterozygous oocytes, could be hypersensitive to chemically induced malsegregation was tested by injecting Rb heterozygous females with low doses of vinblastine (VBL). An intraperitoneal injection of 0.06 or 0.09 mg/kg VBL before the first meiotic division significantly increased the spontaneous frequency of hyperploid oocytes, inducing segregational errors of both the trivalent and normal bivalents. The comparison of these data with VBL effects in B6C3F1 mice showed that single Rb heterozygous oocytes are more sensitive to VBL-induced meiotic aneuploidy than oocytes with a standard karyotype. Although segregation distortion has been repeatedly shown in the progeny of Rb heterozygous mice with a significant excess of all telocentric balanced offspring, it has never been demonstrated whether this is a primary event occurring during meiotic segregation or a consequence of selective postconceptional death. In this study, we showed that preferential segregation occurred during female meiosis in all the Rb stocks tested. When segregation distortion was analyzed separately in balanced and unbalanced oocytes, the latter did not show preferential segregation, suggesting that, when the two telocentrics segregated from each other, then the metacentric was randomly directed to the ovum or the polar body.     

Case report: chromatid exchange and predivision of chromatids as other sources of abnormal oocytes detected by preimplantation genetic diagnosis of translocations

Preimplantation genetic diagnosis of translocations can be performed on first polar bodies (PB) at metaphase stage using FISH with whole-chromosome painting DNA probes. Here we report the use of this method in a couple in which the female was a carrier of a balanced translocation 46,XX,t(11;16)(q21;q22). This case unusual in that two polar bodies showed recombination events between the homologue chromosomes of 11 and 16 pairs, resulting in M-II oocytes with monovalent chromosomes having a normal and a derivative chromatid. For this type of case, PGD analysis on polar bodies cannot give a useful result, because, at the second meiotic division, either of these chromatids could remain in the oocyte, resulting in a normal, balanced or unbalanced embryo. PGD analysis on blastomeres can provide a solution. 11 previous cases of PGD of translocations performed by metaphase PB analysis are reviewed.     

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.     

Predisposition for breast cancer in carriers of constitutional translocation 11q;22q

A translocation between the long arms of chromosomes 11 and 22, t(11;22)(q23;q11), is the most frequent constitutional reciprocal translocation in man. This chromosome abnormality has not previously been reported to be associated with an increased risk for neoplasia. The observation of one patient with a constitutional translocation t(11q;22q) and breast cancer prompted us to study the relationship between these two conditions. The incidence of breast cancer was determined in carriers of t(11q;22q). The karyotypes were determined by QFQ-banding, and the breakpoints were then further characterized by fluorescent in situ hybridization. Eight families with a total of 22 balanced carriers were found. In five of these families there was one case of breast cancer each. In another family a case of an unknown malignancy was reported in one member. No other malignancies were found among these patients. The number of breast cancer cases was significantly higher than expected among the translocation carriers (P < .001). The chromosomal breakpoints showed the same localization with the markers used, in the seven families studied. The association of constitutional translocation t(11q;22q) and breast cancer identifies a subset of patients with a highly increased risk for breast cancer who would benefit from counseling and screening. It also suggests the involvement of genes on 11q and/or 22q, in the tumorigenesis of breast cancer.     

Cytogenetic aberrations in Ewing sarcoma: are secondary changes associated with clinical outcome?

BACKGROUND: Ewing sarcoma is associated with a nonrandom pattern of primary and secondary chromosomal aberrations. Whereas the finding of rearrangements of chromosome 22, usually in the form of a balanced translocation t(11;22)(q24;q12), is important diagnostically, nothing is known about the potential prognostic impact of the secondary chromosomal aberrations. PROCEDURE: During a 1 3-year-period, short-term cultured tumor samples from 21 children and young adults with Ewing sarcoma were cytogenetically analyzed successfully. RESULTS: Clonal chromosome aberrations were detected in 18 patients, 17 of whom had the characteristic t(11;22)(q24;q12) or variants thereof. The most frequent secondary change was +8, followed by +12, +2, +5, +9, +15, and gain of material from the long and short arms of chromosome 1. The only recurrent secondary change that was restricted to tumors from the ten patients that were dead at latest follow-up was gain of 1q material. Furthermore, all three patients with tumors with chromosome numbers over 50 had died, and the only patient with a tumor karyotype lacking chromosome 22 rearrangement was alive without evidence of disease. CONCLUSIONS: These data and previously published results indicate that the karyotypic pattern not only may be of diagnostic significance but also may be important prognostically.     

Partial duplication of 3q and distal deletion of 11q in a stillbirth with an omphalocele containing the liver, short limbs, and intrauterine growth retardation

We describe a female stillbirth with duplication of 3q21-->qter and deletion of 11q23-->qter resulting from an unbalanced segregation of a maternal t(3;11) reciprocal translocation. The proband had some of the clinical features consistent with those seen in patients with dup(3q) syndrome or distal del(11q) syndrome. Prenatal sonographic examination showed short limbs, intrauterine growth retardation, and an omphalocele containing the liver.     

Meiotic segregation, recombination, and gamete aneuploidy assessed in a t(1;10)(p22.1;q22.3) reciprocal translocation carrier by three- and four-probe multicolor FISH in sperm

Meiotic segregation, recombination, and aneuploidy was assessed for sperm from a t(1;10)(p22.1;q22.3) reciprocal translocation carrier, by use of two multicolor FISH methods. The first method utilized three DNA probes (a telomeric and a centromeric probe on chromosome 1 plus a centromeric probe on chromosome 10) to analyze segregation patterns, in sperm, of the chromosomes involved in the translocation. The aggregate frequency of sperm products from alternate and adjacent I segregation was 90.5%, and the total frequency of normal and chromosomally balanced sperm was 48.1%. The frequencies of sperm products from adjacent II segregation and from 3:1 segregation were 4.9% and 3.9%, respectively. Reciprocal sperm products from adjacent I segregation deviated significantly from the expected 1:1 ratio (P < .0001). Our assay allowed us to evaluate recombination events in the interstitial segments at adjacent II segregation. The frequencies of sperm products resulting from interstitial recombination in chromosome 10 were significantly higher than those resulting from interstitial recombination in chromosome 1 (P < .006). No evidence of an interchromosomal effect on aneuploidy was found by use of a second FISH method that simultaneously utilized four chromosome-specific DNA probes to quantify the frequencies of aneuploid sperm for chromosomes X, Y, 18, and 21. However, a significant higher frequency of diploid sperm was detected in the translocation carrier than was detected in chromosomally normal and healthy controls. This study illustrates the advantages of multicolor FISH for assessment of the reproductive risk associated with translocation carriers and for investigation of the mechanisms of meiotic segregation of chromosomes.     

Partial trisomy 7p associated with familial 7p;22q translocation

A newly described partial trisomy of the short arm of chromosome number 7 is reported in a familial translocation between 7 and 22. The unbalanced translocation was found in one family member, the propositus, and the balanced form in 5 other members. The possibility of this translocation being a rare telomeric attachment previously undescribed in humans is discussed. Prominent clinical features include general mental and motor retardation, microbrachycephaly, and cardiac and oral abnormalities.     

A case of HTLV-I associated polyradiculoneuropathy and cerebral white matter lesions with smouldering type adult T cell leukemia

Chronic myelogenous leukemia (CML) is associated with an acquired karyotypic abnormality, the Philadelphia (Ph) chromosome, in 95% of cases. The Ph chromosome is the product of a balanced translocation that results in a hybrid gene that is considered essential for the pathogenesis of this disease. We have found a complex translocation involving chromosomes 9, 12, and 15 in a 42-year-old Haitian male with the clinical findings of CML. Complex translocations have been shown to result in the masking of the Ph chromosome. We used a mixture of two BCR-specific DNA probes for Southern blot analysis in order to test this hypothesis in our patient. High-molecular weight DNA was digested with the restriction enzymes BglII, BamHI and HindIII. The BglII digestion revealed the presence of two abnormal fragments of 3.9 and 3.0 kb and the BamHI digestion an abnormal 15-kb fragment. These data suggest there is a breakpoint in region 2 of M-bcr. The identification of this breakpoint confirms our hypothesis that a rearrangement involving 22q11 has occurred in the leukemic cells of our patient. A secondary translocation involving chromosomes 12 and 15 has hidden the effects of this translocation. Combined cytogenetic and molecular analysis establishes the karyotype of our patient as 46,XY,t(9;12;15;22)(q34;q12;q21;q11).     

De novo balanced 5;21 translocation in a child with acrobrachycephaly, ventriculomegaly, pulmonary stenosis, ectopic anus and mental retardation

An apparently balanced de novo reciprocal translocation t(5;21) (q13;q22) was demonstrated in a girl with acrobrachycephaly, ventriculomegaly, pulmonary stenosis and anal malformation. The possible relationships between her karyotype and malformations are discussed.     

A balanced autosomal reciprocal translocation in an azoospermic bull

This appears to be the first reported case of a bull with a balanced autosomal reciprocal translocation associated with azoospermia. The analysis includes somatic chromosome banding, conventional meiotic analysis, and electron microscopy of synaptonemal complexes (SCs). The karyotype of the bull was found to be 60,XY,rcp(8;13)(q11;q24). Electron microscopy of SCs in microspread pachytene spermatocytes revealed a high incidence of terminal asynapsis of the smallest arm of the quadrivalent. Most quadrivalents with such asynapsis and few with nonhomologous synapsis showed associations with the XY sex bivalent, leading to complete meiotic arrest at late pachynema. Except for one diakinetic cell, no diplotene and subsequent stages were encountered in air-dried meiotic preparations. The presence of degenerating primary spermatocytes in SC preparations, as well as in testicular sections, and the absence of spermatozoa in ejaculates confirm the chromosomally derived male sterility of the bull. X-chromosome reactivation, evidenced by the cytomorphological reversal of associated sex bivalents, appeared to be the initial step in the degeneration of spermatocytes. Consequently, the formation of a separate, fully developed XY body, which was previously demonstrated on the periphery of spermatocyte nuclei in fertile bulls, could not be attained in this case. Extensive end-to-end association of autosomal bivalents in meiotically arrested, as well as degenerating, spermatocytes was a consistent and unique observation of this study. Such associations may lead to enhanced reactivation of the X chromosome.     

Cytogenetic abnormalities in pediatric myelodysplastic syndrome: a report of three cases

Three consecutive cases of pediatric myelodysplastic syndrome (MDS) diagnosed over a three-year period in Queen Mary Hospital, Hong Kong, were described. Depending on the classification system used, they comprised two cases of chronic myelomonocytic leukemia (CMMoL) of which one can be reclassified as juvenile chronic myeloid leukemia (JCML) and one cases of refractory anemia with excess of blasts (RAEB) or an alternative diagnosis of atypical CML. Cytogenetic abnormalities were detected in all of them on examination of bone marrow cells. Of the two CMMoL, one had monosomy 21, whereas the other had hypodiploidy. The patient with RAEB had a complex karyotype of 46,X,del(X)(q24),t(1;7) (p22;q32),add(15)(q26)(8). The balanced translocation (1;7) seen in this patient was exceedingly rare and, to the best of our knowledge, was reported only twice in the literature. The karyotypic abnormalities that we saw in our patients were not well recognized in pediatric MDS. This report emphasizes the importance of cytogenetic study in children suspected of suffering from MDS, which remains a rare disorder of childhood, and a need to rationalize current classification schemes.     

Thyroid hemiagenesis

The translocation t(12;22)(p13;q11) has been consistently described in myeloid malignancies and shown to result from a fusion between the TEL and MN1 genes. Previously described deletions of 12p in acute lymphoblastic leukemias have been recently shown to harbor undetected translocations involving the TEL gene at 12p13. We document a case of an aggressive chronic B-cell leukemia whose cells had trisomy 12 and two unbalanced translocations involving 12p13, including a t(12;22)(p13;q11) as shown by conventional cytogenetics and fluorescence in situ hybridization (FISH). The 12p13 breakpoint of the t(12;22)(p13;q11) was telomeric to the TEL gene, and the second unbalanced translocation with breakpoint 12p13 resulted in the deletion of TEL. This case demonstrates that TEL gene deletions may be relevant in cases of mature B-lymphoproliferative diseases.     

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.     

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.     

Characterization of the breakpoints in unbalanced t(5;11)(p15;p15) constitutional chromosome translocations in two patients with beckwith-wiedemann syndrome using fluorescence in situ hybridisation

Although the majority of patients with Beckwith-Wiedemann syndrome (BWS) have a normal karyotype, the study of those rare patients with a cytogenetic abnormality has given considerable insight into the genetics of this condition. The karyotypic abnormalities found include partial chromosome duplications of paternal origin and maternally derived translocations which usually involve the 11p15 region and provide one of the lines of evidence for the location of the BWS gene(s). Because the extent of the duplicated region in these patients is variable, the phenotypic expression of BWS is presumably due to the presence of a common duplicated region. Two unrelated patients with BWS were both noted to have a similar unbalanced t(5;11)(p15;p14) translocation. The parents in both families were unaffected but both fathers carried a balanced translocation involving the same chromosomes. Since the extent and nature of the duplication apparently determines the complex phenotypes seen in these patients, we undertook a detailed analysis of the extent of the triplicated region using fluorescent in situ hybrisation (FISH). Despite having markedly different phenotypes and presenting in disimilar ways the two patients had apparently identical duplication breakpoints.