A 22/22 translocation carrier with recurrent abortions demonstrated by a Giemsa banding technique

Summary a 22/22 Robertsonian translocation has been identified in a woman with recurrent abortions by a Giemsa banding technique. Cytogenetic studies of the embryonic tissue derived from one of her spontaneous abortions have demonstrated that the aborted fetus had a 46,XX,-22,+t(22q22q) karyotype.     

A familial translocation t(6q+;8q-) identified by fluorescence microscopy

Summary A balanced translocation t(6q+;8q-) was identified by fluorescence studies in a family with multiple spontaneous abortions. It is suggested that a zygote, monosomic for the long arm of chromosome No. 8 is not viable.

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Zusammenfassung Eine balancierte Translokation t(6q+;8q-) wurde durch Fluorescenzuntersuchungen in einer Familie mit mehreren spontanen Aborten nachgewiesen. Es wird betont, daß eine Zygote mit Monosomie des langen Armes vom Chromosom 8 nicht lebensfähig ist.

     

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.     

The segregation of a translocation t(1;4) in two male carriers heterozygous for the translocation

Summary We examined the meiotic segregation pattern of a t(1;4)(p36.2;q31.3) reciprocal translocation in two male cousins heterozygous for the translocation. The wife of subject 1 had four recognized spontaneous abortions and two carrier daughters, and the wife of subject 2 had three recognized spontaneous abortions and no liveborn children. The results showed that subject 1 had an imbalance rate of 54% and subject 2 had an imbalance rate of 61% with respect to the translocation. This was not statistically different (P = 0.3174) and the 95% confidence intervals overlapped for each segregation type. The sex ratio of X- and Y-bearing sperm was not statistically different than the expected 50%. The rate of structural abnormalities was 11.3% in subject 1 and 17.8% in subject 2. Both of these values were above the range of control subjects in our lab, but only subject 2's value fell outside the 95% confidence interval for the control population.     

A new RFLP withStuI and probe cX55.7 (DXS105) and its usefulness in carrier analysis of fragile X syndrome

Summary The case of a healthy 29-year-old woman is reported who had a history of three early spontaneous abortions. Chromosomal analysis of the mother of the patient showed a balanced karotype of 46,XX,t(6;11)(q24; q21), whereas the chromosomes of her father were normal. The karotype of this patient is thus a combination of a familial translocation 6;11 and a de novo translocation 4;11, which is very rare.     

A novel family-specific translocation t(2;20)(p24.1;q13.1) associated with recurrent abortions: molecular characterization and segregation analysis in male meiosis

In the present study, we present a novel reciprocal translocation t(2;20)(p24.1;q13.1) and its segregation in a three generation family. The rate of miscarriages (50%) in pregnancies from male translocation carriers could be explained by unbalanced translocation-bearing spermatozoa found with a frequency of approximately 55% in the entire sperm population of a t(2;20)(p24.1;q13.1) carrier. These imbalanced spermatozoa mainly present as 2, der(20) and der(2), 20 missegregated (approximately 46%) while adjacent 2 and 3:1 segregation patterns account for approximately 5% and 4% of imbalances, respectively. While the translocation is associated clearly with an increased risk of early abortions (7/12) in both male and female carriers, no malformed livebirths were observed. Our results suggest complete embryonic lethality of imbalanced offspring. With respect to a high rate of segregation to 2, der(20) and to der(2), 20 imbalanced spermatozoa in male translocation carriers and with respect to known cases of partial trisomy 2p and 20q we consider that their corresponding monosomies result in fetal loss. This is the first study reporting multiple abortions associated with partial monosomy 20q13.1-->qter and 2pter-->p24.1 and the first report on the frequency of chromosomal imbalances in gametes of a male t(2;20)(p24.1;q13.1) heterozygote.     

Successive spontaneous abortions including one with whole-arm translocation between chromosomes 2

Summary A family with five induced and seven spontaneous abortions and no live births is described. Four of the seven spontaneous abortuses were available for cytogenetic examination and three were successfully karyotyped. Their karyotypes were 46,XX; 46,XX/46,XX,t(2;2)(2p2p;2q2q); and 46,XY. The karyotypes of the parents were normal. The origin of the 2p/2p and 2p/2p translocation in one of the abortuses was assigned to an interhomologous whole-arm translocation in an early mitotic division in a conceptus with a 46,XX karyotype.     

Familial C/D translocation t(9;13)(9p23;13q21) in a male associated with recurrent abortion

Summary A familial reciprocal translocation, established by R-banding as t(9;13) (9p23; 13q21), is described in a phenotypically normal male carrier, whose father is also a balanced carrier and wife had four consecutive spontaneous abortions. The role of translocation in reproductive failure through production of chromosomally unbalanced gametes or by impairment of the spermatogenesis is briefly discussed.     

Novel chromosomal insertional translocation in chicken uncovered by double color FISH

A novel insertion 78,ZZ or 78,ZW, ins(3;1)(q25q27;undetermined) was revealed in chicken by double color fluorescent in situ hybridization (FISH). A fragment of chromosome 1 spanning either from q13-14 to q34-35, or from q14-21 to q36-41 bands, had been translocated to chromosome 3 at a site located between q25 to q27 bands. This has resulted in the generation of an interstitial deletion in chromosome 1 and an insertional translocation in chromosome 3. Chickens with this balanced insertional translocation are asymptomatic carriers and their fertility is not affected, but embryo mortality increases. Greater than 50% occurrence of unbalanced gametes are observed. However, progeny sex ratio is not affected.     

Four familial translocations ascertained through spontaneous abortions

Summary In a study of 514 spontaneous abortions, 194 were found to have a chromosome anomaly. Of these, 4 (2.1%) were unbalanced translocations. Three of the translocations were Robertsonian (13q14q) and one was reciprocal. Each translocation was ascertained independently and each was associated with a balanced rearrangement in a carrier parent.     

Translocation +(7p+; Bq-) associated with recurrent abortion.

A balanced translocation was found in a normal female with a history of four abortions. On the basis of the Giemsa-banding pattern the abnormality was interpreted as to be a translocation of a part of the long arm of chromosome 13 to the short arm of chromosome some 7:t(7;13)(7qter leads to 7p22::13q14 leads to 13qter;13q14 leads to 13pter::7p22 leads to 7 pter). Problems in genetic counseling are discussed with respect to this case.     

A family with two different chromosomal translocations

The proband was a 22-year-old woman who had two spontaneous abortions in the first trimester of pregnancy. She had a consanguineous marriage with no history of malformation or developmental disorders in the family. Her gynecological examination was normal. Chromosome analysis of the family showed two different katyotypes 46,XY,t(1;16)(p22;p13) and 46,XX,t(1;16)(q24;q24) using high-resolution banding (HRB). Proband's family was also examined for chromosome analysis. A t(1;16)(p22;p13) was found in the husband's father and other relatives, and a t(1;16)(q24;q24) translocation in the proband's family. This second tanslocation is not found in her parents.     

A rare reciprocal translocation (12;21) segregating for nine generations

An autosomal reciprocal translocation (12;21) was found in five seemingly unrelated families in Finland. Three families had had multiple spontaneous abortions and two families had a child with Down's syndrome. The genealogies of the five families were traced using population registries, and four families were found to have a common ancestor born in 1752. Kinship to the fifth family could not be established but its ancestors were traced back to the same rural parishes as those of the four other families. The translocation segregated at the same frequency as normal chromosomes. A statistically insignificant increase in spontaneous abortions was detected when the matings of translocation carriers were compared with non-carrier matings. The increase may however be clinically significant. These results permit more accurate counselling in these and similar translocation families.     

A cytogenetic study of recurrent abortion

Summary Chromosomal analysis was performed in a series of 27 women with repeated spontaneous abortions and in 16 of the husbands. In one woman a balanced translocation of the type 13q/15q was detected, and a pericentric inversion of a chromosome A₁ was found in the husband of another proband. The significance of these findings is discussed.

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Zusammenfassung Bei 27 Frauen mit wiederholten Aborten und bei 16 zugehörigen Ehemännern wurden Chromosomenanalysen durchgeführt. Bei einer Probandin fand sich eine balancierte Translokation 13q/15q, bei dem Ehemann einer anderen Probandin eine perizentrische Inversion eines Chromosoms A₁. Die Bedeutung der Befunde wird diskutiert.

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The study was supported by the Deutsche Forschungsgemeinschaft, Sonderforschungsbereich 35.     

A family with a high risk of segregation for an autosomal unbalanced reciprocal translocation

Summary A family with autosomal reciprocal translocation t(4;13) (q25;q31) with a sibship comprising 2 children with unbalanced karyotypes, der(13) partial trisomy 4q, 1 child with the balanced translocation, and 2 abortions were studied. The segregation risk of unbalanced derivation in reciprocal translocations is discussed. The clinical picture of the 2 children with partial trisomy 4q is compared with similar cases.     

Segregation and fertility analysis in an autosomal reciprocal translocation, t(1;8)(q41;q23.1).

We report a previously undescribed autosomal reciprocal translocation, t(1;8)(q41;q23.1). It segregates in three families whose common origin lies at least 11 generations back. No examples of unbalanced karyotypes were encountered. Moreover, there was no circumstantial evidence that such live births had occurred during earlier generations. Couples in which one spouse was a translocation carrier were compared to related couples with normal karyotypes. The 15 carrier families had significantly more spontaneous abortions (32%) than the 22 normal couples (10%), irrespective of the sex of the carrier parent. However, the mean number of children was equal in both groups (2.0 and 2.4). Carrier families produced 17 children with a balanced translocation and seven with a normal karyotype. This deviates significantly (P = .04) from the expected 1:1 ratio. We conclude that this malsegregation helps to maintain the translocation in the population. These results show that empirically derived 1:1 segregation ratios previously reported in series that combine many different translocations do not apply to all individual translocations.     

罗伯逊易位分子机理初探

目的：探讨复发性自然流产与染色体罗伯逊易位间的关系。方法：采用人外周血淋巴细胞培养,常规G显带技术行染色体核型检查,并结合临床资料对其进行分析。结果：57对复发性自然流产夫妇中,检出罗伯逊易位染色体核型4例,检出率3.51%。结论：罗伯逊易位是导致复发性流产的重要原因之一,对复发性自然流产患者进行常规的染色体检查及遗传咨询具有一定的临床意义。     

Inversion of chromosome 2 (p11p13): Frequency and implications for genetic counselling

Summary We report a case of an X-autosome translocation t(X;4)(q13;p16) found in both sexes in three generations. The anomaly was diagnosed in a couple referred for cytogenetic investigation as a result of three spontaneous abortions. With the exception of the miscarriages there are no particularities in the gynecologic data of the woman or in the pedigree. In all 50 lymphocytes and in 66 of 68 fibroblasts investigated the normal X chromosome was the late replicating one.     

Analysis of translocations observed in three different populations. I. Reciprocal translocations

A sample of 437 reciprocal translocations was classified into three groups according to their method of ascertainment (Group I = couples with repeated abortions; Group II = karyotypically unbalanced carriers; Group III = balanced translocation heterozygotes). Statistical analysis showed that the distributions of chromosome breaks observed in the three groups could not be accounted for by chromosome arm length alone. In couples with repeated abortions, an excess of breaks in 7p, 17p, and 22q was found, whereas in the balanced translocation heterozygotes an excess of breaks was found only in 11q. An excess of breaks was found in arms 9p, 14p, 18p, 18q, 21q, and 22q in karyotypically unbalanced probands. A significant decrease of breaks in the medial chromosome regions was accompanied by a concomitant increase in the terminal regions in all groups. The three groups demonstrated different distributions of chromosome arm involvement in the observed translocations. Balanced translocation heterozygotes had the highest frequency of large (greater than the length of 4p) translocated segments and an excess in the frequency of large-large translocations, whereas karyotypically unbalanced probands had the highest frequency of small (shorter than 21q) translocations and an excess in the frequency of small-small translocations. For each type of chromosomal imbalance observed, the balanced translocation heterozygotes demonstrated the greatest potential imbalance and the karyotypically unbalanced probands the least.     

Paracentric inversion of chromosome 15(q15q24): description of three families

Three unrelated families with paracentric inversion of chromosome 15(q15q24) are reported. An additional pericentric inversion of chromosome 9 with breakpoints in p11.2q13 was also observed in one of the three families. Reproductive problems, such as stillbirths, spontaneous abortions and two live-born children with multiple abnormalities, were present.