Translocation t(13;14) in nine generations with a case of translocation homozygosity

The Robertsonian translocation 5(13;14)(p11;q11) was studied in three families with probable common ancestry in Eastern Finland. In the largest family the translocation has segregated through at least nine generations. The same family also included a female who was homozygous for t(13;14). No clear-cut effect of the translocation on fertility could be demonstrated and only one case of trisomy 13 was recorded in the offspring of t(13;14) carriers. The results are discussed, with implication for human chromosomal evolution.     

Familial t(6;21)(p21.1;p13) translocation associated with male-only sterility

A 38-year-old male with primary infertility was referred for cytogenetic investigation. Karyotype analysis revealed a 46,XY,t(6;21)(p21.1;pl3) translocation. The Ag-nucleolar organizer regions (NORs) banding technique demonstrated that the 21p NORs were retained in the derivative and actively transcribed. Family studies showed that three brothers, two sisters and their mother carried the t(6;21). All carrier males suffered from primary infertility with severe oligoasthenoteratospermia or azoospermia, whereas at least two of the three carrier women were fertile. The region of the translocation breakpoint was narrowed down cytogenetically and by fluorescence in situ hybridisation as 21p13 and 6p21.1. Southern blot analysis showed that the gene ZNF165, which maps to this region and which is specifically expressed in the testis, was not disrupted by the translocation. However, studies performed on testicular biopsy showed spermatocyte meiosis anomalies. We discuss the possible mechanisms by which the translocation might affect meiosis in spermatogenesis and lead to infertility.     

45,XY,-13,-14,-21,+t(13;14),+t(21;21)一例

患儿男,1岁9个月.系第2胎第1产,第1胎人工流产,足月顺产,眼距宽,双手通贯掌,患儿体重9.5 kg,智力低下.父母非近亲结婚,无家族史,生育年龄为母19岁、父26岁.细胞遗传学检查:外周血淋巴细胞培养,G带分析,计数30个分裂相,分析5个,患儿核型为:45,XY,-13,-14,-21,+t(13;14),+t(21;21),父母核型正常.     

A de novo translocation, 14q21q,with a microchromosome—14p21p

A familial translocation, t(14;21)(14p21p;14q21q), in a mother and her child is described. The translocation was ascertained through the birth of a Down syndrome baby with the chromosome constitution 47,XX,-14, +der 14, +der 21,t(14;21)(q11; p12) mat. A 1:3 segregation in the maternal meiosis is suggested for the evolution of the unbalanced chromosome state. The main translocated chromosome 14q21q mimics the product of a Robertsonian translocation, while the 14p21p chromosome has the morphology of a satellited microchromosome. The cytogenetic nature of this translocation is discussed.     

Segregation of chromosomes into the spermatozoa of a man heterozygous for a 14;21 Robertsonian translocation

Twenty-four spermatozoa from a man heterozygous for a Robertsonian translocation (45,XY,-14,-21,+t(14q;21q) were studied cytogenetically in order to determine the meiotic segregation of the translocation. When compared to the expected 1:1 ratio we observed a greater number of chromosomally normal sperm than sperm with the balanced translocation. Three sperm carried the translocation in an unbalanced form.     

Familial t(11;13)(q21;q14) and the duplication 11q, 13q phenotype

Cases of duplication of distal 11q or proximal 13q have been reported independently. A specific translocation resulting in duplication of distal 11q, [der(22)t(11;22)(q23;q11)], has been documented in over 40 cases. We report on a male fetus with chromosomal excess of both distal 11q and proximal 13q resulting from a familial translocation. This case supports the causal association of duplication 11q with neural tube defects. © 1993 Wiley-Liss, Inc.     

一家三代Robertson易位t(15;21)及其优生遗传咨询的探讨

本文报道一家三代罗氏易位t(15；21)，并探讨唐氏综合征核型分类与临床症状的相关性以及罗氏易位、平衡易位、不平衡易位、遗传效应、再发风险、配子形成、产前诊断、产前筛查、存在问题与未来展望，为读者提供唐氏综合征优生遗传咨询有价值的参考资料。     

Homozygosity for a Y/22 chromosome translocation: t(Y;22) (q12;p12/13)

A newborn girl, homozygous for a balanced Y/22 chromosome translocation is described. This unique karyotype was detected during prenatal chromosome studies in the first pregnancy of a 26-year-old woman. Amniocentesis was performed because of clinical evaluation of severe fetal growth retardation in the 28th week of gestation. The cytogenetic results were confirmed using a lymphocyte culture after birth in the 30th week. Subsequent chromosome studies of the parents were hampered by the fact that the pregnancy was thought to be the result of artificial insemination with donorsperm. Nevertheless both, consanguineous, parents were shown to be carriers of the same, singular, chromosome translocation and the spermdonor could be excluded from paternity by bloodgroup- and HLA studies. Distamycin-A-DAPI chromosome staining and DNA studies of the mother were used to confirm the involvement of the Y-chromosome in this translocation. The probanda is developing quite normally at the age of 21 months.     

Myotonic dystrophy and autosomal balanced translocation t(2; 20) (p21; q11)

The present paper reports the concurrence of Myotonic Dystrophy and an autosomal balanced translocation t(2;20)(p21;qll), both occurring de novo in a 21–year-old female.     

Sperm chromosome complements in a man heterozygous for a reciprocal translocation 46,XY,t(9;13)(q21.1;q21.2) and a review of the literature

Sperm chromosome complements were studied in a man heterozygous for a reciprocal translocation t(9;13)(q21.1;q21.2). A total of 89 spermatozoa were karyotyped after in vitro penetration of hamster eggs. The frequencies of alternate, adjacent 1 and adjacent 2 segregations were 46.9%, 35.8% and 17.3% respectively. For alternate segregation, the number of normal spermatozoa (21) was not significantly different from the number of spermatozoa carrying a balanced form of the translocation (17), as theoretically expected. The proportion of spermatozoa with an unbalanced form of the translocation was 53.1%. There was no evidence for an interchromosomal effect since the frequency of numerical abnormalities (unrelated to the translocation) was within the normal range of control donors. Data from a total of 31 reciprocal translocations studied by sperm chromosomal analysis were reviewed.     

Meiotic segregation in spermatozoa of a 45,XY,-14,der(18)t(14;18)(q11;p11.3) translocation carrier: a case report

A 35-year-old male was found to have a 45,XY,-14,der(18)t(14;18)(q11;p11.3) karyotype during the investigations for a couple with infertility for 8 years. Two sperm samples were obtained and analysed in triple fluorescence in situ hybridization (FISH) with the D18Z1 and LSI IGH/BCL2 probes. The frequency of gametes exhibiting a normal or balanced chromosomal equipment was 87.26 and 90.97% in samples 1 and 2, respectively. No statistically significant difference was found between the results of meiotic segregation of both samples. These proportions are close to those observed among Robertsonian translocation carriers. They can probably be explained by the formation of trivalent in cis configuration during meiosis I between the derivative chromosome and the normal chromosomes 14 and 18, as in Robertsonian translocation carriers. These results suggest that the configuration adopted at pachytene strongly determines the segregation mode that will be preferentially followed during anaphase I.     

Partial trisomy 6q, due to balanced maternal translocation (6;22) (q21; p13) or (q21; pter)

We report a stillborn infant with partial trisomy 6q who had several major congenital malformations not previously associated with this chromosomal aberration. These included occipital encephalocele, ambiguous genitalia with imperforate anus, omphalocele and unilateral hydronephrosis. The infant's karyotype was 46, XY,-22, der(22), t(6;22)(q21; p13) or (q21;pter)mat. The mother and maternal grandmother are balanced translocation carriers.     

Chromosome 18 translocation (18;21) (p11.1;p11.1) associated with psychosis in one family

In the course of recruiting families with 2 schizophrenic siblings for genome screening and linkage studies, a family was found with mental retardation, schizophrenia, and/or other related psychotic illnesses in individuals who also had an unbalanced or balanced translocation between chromosomes 21–18 [t(18;21) (p11.1;p11.1)]. The pericentric region of chromosome 18 has already been noted as a possible location of a gene for bipolar psychosis. The family described here provides further evidence that this region should be examined for a candidate psychosis gene. © 1996 Wiley-Liss, Inc.     

Segregation of chromosomes in sperm of a t(X;18)(q11;p11.1) carrier inherited from his mother: case report

Balanced reciprocal translocations are the most common structural abnormalities; most involve two autosomes while a few involve a gonosome (X or Y chromosome) and an autosome. These rearrangements are usually associated with infertility and/or a higher risk of chromosomal imbalances among offspring. This 26 years old man was first seen because of a 3-year history of primary infertility. He had been found to have a translocation, t(X;18)(q11;p11.1), inherited from his mother when he was 9 years old. Semen analysis showed a very severe oligoasthenoteratozoospermia (OAT). A total of 447 spermatozoa were analysed using three-colour fluorescent in situ hybridization (FISH). The alternate segregation pattern, leading to a normal or balanced chromosomal content, was found in 54.36% of the spermatozoa studied. The frequencies of Adjacent I, Adjacent II, 3:1 segregation and diploidy (or 4:0 segregation) were 8.28, 5.14, 22.37 and 2.01%, respectively. Balanced reciprocal translocations between an autosome and the X chromosome lead to important disruptions in human spermatogenesis. Almost all the males with an X-autosome translocation have azoospermia. The man reported here had very severe OAT and is the first in whom the meiotic segregation pattern was analysed. This case further emphasizes the interest in performing FISH studies in infertile males with a chromosomal translocation to provide them with a personalized imbalance risk.     

A case of Prader – Willi syndrome arising as a result of familial unbalanced translocation t(11;15)(q25;q13)

We report on a case of Prader-Willi syndrome (PWS) with a true reciprocal unbalanced translocation, 45,XX,-15,der(11)t(11;15)pat. The proposita was diagnosed clinically as having severe PWS. Molecular studies revealed loss of the paternal methylation pattern at locus D15S63 and a deletion encompassing the loci from at least D15S10 to D15S97 of paternal chromosome 15. FISH studies confirmed the deletion of 15q11-q13 region and the presence of two telomeres on all chromosomes. The proposita's father, the father's sister and their mother are all carriers of the same balanced translocation t(11;15)(q25;q13). By genomic imprinting we would expect that if the father's sister were to give birth to a child with the same unbalanced translocation as the proband, it would be affected by Angelman syndrome.
To date, a similar familial unbalanced translocation due to loss of the small chromosome 15 derivative has not been described.     

Multiple congenital anomalies in a man with (X;6) translocation

X;autosome translocations in humans, often associated with congenital anomalies or with gonadal dysgenesis syndromes, are informative for the study of X-linked gene expression and of the phenomenon of X chromosome inactivation. When such translocations occur in association with multiple congenital anomaly (MCA) syndromes, the observed phenotypes are not always attributable solely to disruption of specific genes, if X-inactivation spreads onto the translocated autosome, rendering some distal genes inactive. We report on a man with multiple congenital anomalies and a maternally inherited (X;6)(p22.1;p25) translocation. He has abnormalities not described in the Klinefelter or 6p deletion syndromes. His unique findings constitute a recognizable syndrome, which is likely caused by disomy for a region of Xp in conjunction with a partial 6p deletion. © 1994 Wiley-Liss, Inc.     

Sperm chromosome complements in a man heterozygous for a reciprocal translocation t(2; 3)(q24;p26)

Sperm chromosome complements were studied in a man heterozygousfor a reciprocal translocation t(2; 3)(q24;p26). This man wasidentified during a family study after his sister was investigatedfor amenorrhea. A total of 92 spermatozoa were karyotyped afterin-vitro penetration of hamster eggs. The frequencies of alternate,adjacent 1, adjacent 2 and 3: 1 segregations were 55.4, 36.1,7.2 and 1.2% respectively. For alternate segregations, the numberof normal spermatozoa (n < 25) was not significantly differentfrom the number of spermatozoa carrying a balanced form of thetranslocation (n < 21), as theoretically expected. The proportionof spermatozoa with an unbalanced form of the translocationwas 44.6%. There was no evidence for an interchromosomal effectsince the frequencies of numerical and structural abnormalities(unrelated to the translocation) were within the normal rangeof control donors.