A reciprocal whole-arm translocation, rcp(1;6)(1p6p;1q6q) in a boar, localization of the breakpoints, and reassignment of the genes for glucose phosphate isomerase (GPI) and calcium release channel (CRC).

A reciprocal whole-arm translocation between chromosomes 1 and 6 in a Swiss Large White boar with reduced fertility was identified by the use of different staining techniques in mitotic metaphase cells, synaptonemal complex analyses, and meiotic chromosome preparations. The karyotype of this boar was demonstrated to be 38,XY,rcp(1;6)(1p6p;1q6q). To further localize the breakpoints more precisely and determine the precise gene locations, several in situ hybridization experiments were performed with a chromosome 1 centromere-specific probe and two other gene probes. The breakage and reunion points of both chromosomes were located in the centromeric regions. The genes for glucose phosphate isomerase and calcium release channel were mapped to 6cen----q12.     

Molecular cytogenetic characterization of a familial balanced reciprocal translocation t(11;18) (q13.3; q23) associated with pregnancy wastage

A new male patient associated with a pregnancy wastage was detected in China. Cytogenetic analyses including G-banding, chromosome painting and observation of synaptonemal complexes (SCs) demonstrated that the pregnancy wastage was associated with a balanced reciprocal translocation t(11;18) (q13.3; q23). The proband was the carrier of the translocation and his karyotype was 46,XY,t(11;18)(11pter-->11q13.3:: 18q23-->18qter; 18pter-->18q23::11q13.3-->11qter). The pedigree was analyzed based on a G-banded karyotype of the nine familial members. The translocation chromosomes came from the proband's mother. The result of the SC observation in the proband showed that each of the spermatocytes displayed one quadrivalent during their pachytene stages. In the quadrivalents, there existed homologous and nonhomologous synapses and the latter occurred widely during early, middle and late pachytene stages. The reasons and genetic basis of the pregnancy wastage are discussed.     

Meiotic studies of a human male carrier of the common translocation, t(11;22), suggests postzygotic selection rather than preferential 3:1 MI segregation as the cause of liveborn offspring with an unbalanced translocation

The t(11;22)(q23;q11) translocation is the only non-Robertsonian rearrangement for which there are a large number of unrelated families, apparently with the same breakpoints. These families most often have been ascertained through an abnormal child with the karyotype 47,XX or XY, +der(22) t(11;22)(q23;q11). To explain the high incidence of 3:1 segregants, rarely seen in offspring of carriers of other reciprocal translocations, a number of theoretical models have been suggested. We have used both electron microscope analysis of the synaptonemal complex (SC) and dual-color FISH to investigate the meiotic chromosome behavior in a male carrier of the translocation who has the karyotype 46,XY, t(11;22)(q23;q11). Chromosome synapsis, first-meiotic chiasma configuration, and segregation behavior of this translocation have been analyzed directly. Examination of SCs by electron microscopy showed pachytene-cross formation in 49/50 nuclei. Approximately 50% (26/50) revealed a classical fully synapsed quadrivalent. A proportion of these (10/26), however, showed some central asymmetry, suggesting heterologous synapsis. The remaining cells appeared to have incomplete synapsis. FISH analysis showed only quadrivalents in all 100 metaphase I nuclei. The chiasma frequency was increased within the interstitial segments, in comparison with the same region in normal bivalents. All types of segregation category were found in metaphase II nuclei. There was no indication of preferential 3:1 anaphase I segregation. We conclude that the +der(22) constitution in offspring of carriers of t(11;22)(q23;q11) is not likely to be due to meiotic 3:1 segregation being especially common. Rather, the +der(22) constitution is more likely to be the result of postzygotic selection against other unbalanced karyotypes.     

A case of insertional translocation resulting in partial trisomy 16p

This report concerns the case of a boy with partial trisomy 16p resulting from the insertional translocation of the short arm of chromosome 16 into the long arm of chromosome 1 in his father. He was referred for genetic testing because of mental retardation, short stature, microcephaly, seizures and multiple dysmorphic features. Chromosome analysis performed in the child demonstrated the presence of additional material in the long arm of chromosome 1. Paternal high resolution chromosome analysis and fluorescence in situ hybridisation revealed the following karyotype: 46,XY,ins(1;16)(q42;p13.1p13.3), while the karyotype of the boy is 46,XY,der(1),ins(1;16)(q42;p13.1p13.3)pat. This is the first reported case of partial trisomy 16p due to paternal insertional translocation.     

Partial trisomy 14q due to maternal t(4;14)(p16;q32) in a dysmorphic newborn

Partial Trisomy 14q is a rare chromosomal disorder that mostly results from a parental translocation. We report here a newborn boy with partial trisomy 14q and dysmorphic features that are compatible with previously reported cases. Conventional cytogenetic analysis revealed an extra chromosomal segment at the end of the short arm of chromosome 4. In order to determine the origin of this chromosome region we used subtelomeric FISH technique. Based on the results of these cytogenetic studies and the physical examination, this dysmorphic case was diagnosed as partial trisomy of 14q and his karyotype determined as 46 XY, der(4)t(4;14)(p16;q32) resulting from a balanced maternal translocation identified as 46,XX, t(4;14)(p16;q32).     

Detection of an unbalanced translocation (4;14) in a mildly retarded father and son by flow cytometry

Summary A child with impaired intelligence, minor dysmorphisms, obesity and genital hypoplasia was found to have an apparently balanced translocation, 46,XY,t(4;14)(q12;q13), following cytogenetic analysis. The same rearrangement was also detected in the child's father, who had similar phenotypic abnormalities to his son. Detailed study of flow karyotypes produced from lymphoblastoid cell lines established that in both patients the translocation was in fact unbalanced with approximately 11 million base pairs of DNA (corresponding to about 6.0% of chromosome 4 or 11.0% of chromosome 14) being lost.     

Localization of the human type 5, tartrate-resistant acid phosphatase gene by in situ hybridization

We report the localization of the gene for the human type 5, tartrate-resistant, iron-containing acid phosphatase isoenzyme (HGM designation ACP5) to chromosome 15 (15q22-q26) using the technique of in situ hybridization to metaphase chromosomes. We have localized this gene using peripheral blood chromosomes obtained from both a normal male and an individual carrying an unbalanced translocation involving chromosome 15 [45,XY,-15,-18,+der(18)-t(15;18)(q13;p11)]. In addition, we have demonstrated the utility of employing a standard fluorescent staining technique (distamycin/DAPI) to an emulsion-coated, Wright-stained, and destained chromosome preparation.     

Aberrations of the synaptonemal complexes in a male 46,XY,-14,+der(14)t(Y;14)

An unbalanced translocation 46,XY,-14,+der(14)t(Y;14)(q11;p11) was observed in an azoospermic male, with reduced spermatogenesis and absent spermiogenesis. At the pachytene stage of spermatocyte 1, the segments of the 2 Y chromosomes, fluorescent with quinacrine mustard, were always found close together. This proximity was also demonstrated by the study of synaptonemal complexes, which showed, in addition, an unusual hypercondensation of the proximal segment of bivalent 14, adjacent to the translocated Y chromosome. This allows us to propose that this hypercondensation might correspond to an inactivation of the translocated autosome, which could be responsible of the degeneration of the germ cells.     

Additional chromosome in a child as a result of a balanced reciprocal translocation t(12;18)(p13;q12) in his mother's karyotype

In this case report we present a child with an additional chromosome in the karyotype. The karyotypes of the boy and his parents were analyzed by use of a conventional banding technique (GTG) and fluorescence in situ hybridization (FISH). Probes painting whole chromosomes 12 and 18 were used in FISH. Cytogenetic examination of the parents revealed that his mother was carrying balanced reciprocal translocation between chromosomes 12 and 18. Her karyotype was described as 46,XX,t(12;18)(p13;q12). Father's karyotype was normal, described as 46,XY. The boy's karyotype was defined as 47,XY,+der(18)t(12;18)(p13;q12). The additional chromosome appeared probably due to 3:1 meiotic disjunction of the maternal balanced translocation, known as tertiary trisomy. The mother displayed a normal phenotype and delivered earlier a healthy child. However, the boy with the unbalanced karyotype shows multiple congenital abnormalities.     

XY pair associates with the synaptonemal complex of autosomal male-sterile translocations in pachytene spermatocytes of the mouse (Mus musculus)

Analysis of the chromosome behaviour at pachytene has been performed by means of the silver staining technique visualizing the synaptonemal complexes (SCs) in male mice heterozygous for the male-sterile translocations T(5;12)31H, T(16;17)43H and T(7;19)145H, respectively. The T(9;17)138Ca male heterozygotes and T43H/T43H homozygous males were used as fertile controls. The sterile mice displayed a high frequency (about 60%) of pachytene spermatocytes with autosomal translocation configuration located in close vicinity of the XY pair. The dense round body (XAB), normally located near the X-chromosome axis in fertile males, exhibited abnormal affinity to translocation configuration in the sterile translocation heterozygotes. The incomplete synapsis of autosomes involved in translocation configuration was observed in more than 70% of the pachytene spermatocytes with the male-sterile translocations but in less than 20% of the cells from T138Ca fertile male.s. A hypothesis relating the spermatogenic arrest of carriers of male-sterile rearrangements to the presumed interference with X chromosome inactivation in male meiosis is discussed.     

Male infertility in a case of (Y;6) balanced reciprocal translocation. Mitotic and meiotic study

Summary In a 30-year-old azoospermic male, chromosome analysis revealed an apparently balanced Y-autosome reciprocal translocation, t(Y;6)(Yp6p;Yq6q). Testicular biopsy showed an arrest of spermatogenesis at the First metaphase stage of the meiosis, associated with a considerable desquamation of the germinal epithelium.Meiotic studies showed abnormalities of the sex vesicle at the pachytene stage, and the formation of a chain tetravalent at the diakinesis-metaphase I stage. Possible correlations between the translocation and the defects of spermatogenesis are discussed.     

Synapsis and chiasma distribution in mice heterozygous for translocations in chromosomes 16 and 17

Electron microscopic analysis of synaptonemal complexes and analysis of chiasmata distribution in male mice heterozygous for Robertsonian translocation T(16; 17)7Bnr - (Rb7), for synaptonemal reciprocal translocation T(16;17)43H - (T43), in double heterozygotes for these translocations and in males with partial trisomy of the proximal region of chromosome 17 was carried out. Synaptic disturbances around the breakpoints of the translocations, such as asynapsis of homologous regions of partners and non-homologous synapsis of centromeric regions of acrocentric chromosomes, were revealed. Synaptic regularity in the proximal part of the chromosome 17 appeared to be affected by no t12 haplotype. Good coincidence between sizes of mitotic chromosomes and corresponding lateral elements of synaptonemal complexes was found for all chromosomes, with the exception of Rb7 in trisomics. In the latter karyotype, the proximal part of chromosome 17 involved in Robertsonian fusion seems to be shortened in the course of zygotene and never synapted with homologous segment of neither the acrocentric chromosome 17 nor large product of reciprocal translocation. Drastic increase in chiasmata frequency in the proximal part of chromosome 17 was revealed in heterozygotes for T43H and in trisomics, as compared with the double heterozygotes Rb7/T43. The latter finding was explained by the existence of two independent pairing segments in the former karyotypes.     

Y-autosome translocation and infertility: usefulness of molecular, cytogenetic and meiotic studies

An apparently balanced reciprocal translocation 46,X,t(Y;6) (q11.23 ∼ q12;p11.1) was observed in an infertile man with severe oligozooteratozoospermia. Different mitotic chromosome banding patterns were performed and fluorescence in situ hybridization indicated a breakpoint in the fluorescent Yq heterochromatin. Molecular genetic deletion experiments for the azoospermia factor region in distal Yq11 showed the retention of the DAZ gene and meiotic pairing configurations suggested that the man’s infertility could be due to the pairing behaviour of the Y;6 translocation chromosome with the X chromosome visualised by synaptonemal complex analysis at the electron microscopy level. The morphological appearance of the normal chromosome 6 and the Y;6 translocated chromosome included in the compartment of the sex vesicle may allow an explanation of the degeneration of most spermatocytes after the pachytene stage. Received: 1 August 1997 / Accepted: 25 September 1997     

Spectral karyotyping and fluorescence in situ hybridization analysis of de novo partial trisomy 7p (7p21.2-->pter) and partial monosomy 12q (12q24.33-->qter)

An 8-year-old boy presenting with hypotonia, moderate mental retardation, developmental delay, and psychomotor retardation is reported. Magnetic resonance imaging of the brain at age 3 years revealed a Dandy-Walker variant. Cytogenetic analysis of the peripheral blood revealed a derivative chromosome 12 with unknown additional material attached to the distal region of the long arm of chromosome 12. The parental karyotypes were normal. Spectral karyotyping (SKY) using the 24-color SKY probes and fluorescence in situ hybridization (FISH) using the specific 7p, 7q, 12p, and 12q telomeric probes confirmed a duplication of distal 7p and a deletion of terminal 12q. The karyotype of the proband was designated as 46,XY.ish der(12)t(7;12) (p21.2;q24. 33)(SKY+, 7pTEL+, 12qTEL-). The present case provides evidence for the association of partial trisomy 7p (7p21.2-->pter) and partial monosomy 12q (12q24.33-->qter) with a cerebellar malformation and the usefulness of SKY and FISH in the identification of a de novo aberrant chromosome resulting from an unbalanced translocation.     

Partial trisomy 13 as a result of de novo (6p;13q) translocation

Summary A newborn infant with the clinical features of the Patau syndrome was found to have excess chromosome 13 material present as a tandem translocation involving the short arm of chromosome 6 and the long arm of an extra chromosome 13: 46,XY,t(6;13)(p24;q12). The major part of the long arm of the extra chromosome 13 was attached linearly (tandem translocation) to the short arm of chromosome 6. Both parents were phenotypically and karyotypically normal.     

Quinacrine mustard fluorescence of a second Y chromosome in a Y-autosomal translocation

Summary Screening buccal smears from 97 prisoners by the quinacrine mustard technique revealed one XYY-individual and one Y-autosomal translocation of a second Y chromosome with a 46,XY, D-,t (?15q;Yq)+ karyotype. The translocation chromosome could be identified by its intense fluorescence of the short arm in all 75 metaphases examined.

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Zusammenfassung Untersuchungen von Abstrichen der Mundschleimhaut von 97 Gefängnisinsassen mit der Quinacrine-Mustard-Methode führten zur Aufdeckung eines XYY-Karyotyps und einer Y-autosomalen Translokation eines zweiten Y-Chromosoms mit einem Karyotyp von 46,XY,D-,t(?15q;Yq)+. Das Translokationschromosom konnte durch helle Fluorescenz des kurzen Armes in allen 75 Metaphasen identifiziert werden.

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This work was supported in part by grant number Pa 118/8 from the Deutsche Forschungsgemeinschaft and is part of a thesis by S. F.     

Partial trisomy 4q and monosomy 9p resulting from a familial translocation t(4;9)(q27;p24) in a child with choanal atresia.

A male infant with a deletion of 9p and concomitant duplication of 4q: 46,XY, der(9)t(4;9)(q27;p24), is described. Parental chromosome analysis showed a balanced maternal translocation. To our knowledge, the above cytogenetic and clinical abnormalities have not been described previously. A phenotype comparison is presented with previously reported cases concerning a deletion of 9p and a duplication of 4q.     

A new balanced autosomal reciprocal translocation in cattle revealed by banding techniques and human-painting probes

Three hundred and twenty-two (264 males and 58 females), randomly sampled Grey Alpine cattle individuals from Northeastern Italy, were investigated cytogenetically by both conventional chromosome staining and R-banding. Two hundred and eighty-one (87%) individuals had a normal karyotype and 41 (13%) carried chromosomal aberrations such as (a) rob(1;29) in two individuals, (b) rob(26;29) in 36 individuals, (c) XX/XY-chimerism in two individuals, and (d) an abnormally long chromosome in one individual. All these aberrations except (d) have been described before. GBG-, RBG-, CBA-banding and sequential GBG/CBA- and RBG/CBA-banding techniques revealed that the abnormally long chromosome was the result of a reciprocal translocation between chromosomes 1 (q21-->qter) and 5 (q11-->q33), as confirmed also by chromosome painting with human chromosome 3 and 12 probes. The dam of the carrier bull carried the same translocation, while the grandam showed a normal karyotype. Since the sire of the dam was not available for study, no conclusion about the origin of the chromosome translocation could be drawn. The carrier bull was eliminated because of poor fertility. The dam had three other calves, which all were chromosomally normal. On average the dam had to be served 2.5 times (breed average was 1.2) to be in calf.     

A de novo unbalanced reciprocal translocation identified as paternal in origin in the Prader-Willi syndrome

Summary Interstitial cytogenetic deletions involving the paternally derived chromosome 15q11–13 have been described in patients with the Prader-Willi syndrome (PWS). We report a child with PWS and a de novo unbalanced karyotype –45,XY,–9,–15,+der(9)t(9;15)(q34;q13). Molecular studies with the DNA probe pML34 confirmed that only a single Prader Willi critical region (PWCR: 15q11.2-q12) copy was present. Hybridisation of patient and parental DNA with the multi-allelic probe CMW1, which maps to pter-15q13, showed that the chromosome involved in the translocation was paternal in origin. This is the first example of a paternally-derived PWCR allele loss caused by an unbalanced translocation that has arisen de novo.