Gamete segregation in female carriers of Robertsonian translocations

Eleven female carriers of either 45,XX,der(13;14) (q10;q10) or 45,XX, der(14;21)(q10;q10) underwent hormonal stimulation with the purpose of producing enough oocytes for in-vitro fertilization and preimplantation genetic diagnosis. Polar body biopsy was performed in those oocytes and FISH with painting probes was applied in their metaphase-like first polar body chromosomes. In this way, unbalanced, normal and balanced oocytes could be distinguished and segregation modes ascertained. der(14;21)(q10;q10) produced 42% unbalanced, 37% normal and 21% balanced oocytes (n = 86) while der(13;14)(q10;q10) generated 33% unbalanced, 51% normal and 16% balanced oocytes (n = 69). In both translocations the number of normal oocytes was significantly higher than the number of balanced oocytes. However, while the frequency of unbalanced events involving chromosome 13 and 14 was similar in der(13;14)(q10;q10), there were significantly more abnormalities involving chromosome 21 than 14 in the der(14;21) (q10;q10) cases. When comparing survival rates to term, trisomies from Robertsonian origin seem to survive more often than those originated by non-disjunction in non-translocation carriers. The meiotic segregation patterns found in female Robertsonian translocations are different from those described in male carriers, with higher rates of unbalanced gametes in females than in males.     

Emanuel syndrome due to unusual segregation of paternal origin

Emanuel syndrome is an inherited chromosomal abnormality resulting from 3:1 meiotic segregation from parental balanced translocation carrier t(11;22)(q23;q11), mostly of maternal origin. It is characterized by mental retardation, microcephaly, preauricular tag or sinus, ear anomalies, cleft or high arched palate, micrognathia, congenital heart diseases, kidney abnormalities, structural brain anomalies and genital anomalies in male. Here in, we describe a female patient with supernumerary der(22) syndrome (Emanuel syndrome) due to balanced translocation carrier father t(11;22) (q23;q11). She was mentally and physically disabled and had most of the craniofacial dysmorphism of this syndrome. Our patient had cleft palate, maldeveloped corpus callosum and hind brain with normal internal organs. Additionally, arachnodactyly, hyperextensibility of hand joints, abnormal deep palmar and finger creases, extra finger creases and bilateral talipus were evident and not previously described with this syndrome. Cytogenetic analysis and FISH documented that the patient had both translocation chromosomes plus an additional copy of der(22) with karyotyping: 47,XX,t(11; 22)(q23;q11),+der(22)t(11;22)(q23;q11). We postulated that this rare chromosomal complement can arise from; 2:2 segregation in the first meiotic division of the balanced translocation father followed by non-disjunction at meiosis II in the balanced spermatocyte.     

Proximal monosomy 13

A 45,XX,-13, der(22), rcp(13;22)(q12;q13)mat karyotype was observed in a 7-month-old female with multiple congenital anomalies. Her mother is a balanced t(13;22)(q12;q13) carrier.     

X-autosome translocation with a breakpoint in Xq22 in a fertile woman and her 47,XXX infertile daughter

Summary An unusual case is presented of a fertile woman heterozygous for a balanced X-autosome translocation t(X;12) (q22;p12) with a break-point (Xq22) in the critical region of the X chromosome. The karyotypes of her daughter, who is infertile, and one of her two sons are 47,XXX,t(X;12)(q22;p12) and 46,XY,t(X;12)(q22;p12) respectively. The literature on balanced X-autosome translocations in males and females involving both arms of the X chromosome is reviewed. All 23 of the 36 cases of females with balanced Xq-autosome translocation, that exhibited gonadal failure have a break-point between bands Xq13 and Xq26.     

Pure partial trisomy 5q33-->5q35 resulting from the adjacent-1 segregation of a paternal (5;14)(q33;p12) translocation.

A 14-year-old male was referred for evaluation of mental retardation with short stature and dysmorphic features. His karyotype was 46,XY,der(14)t(5;14)(q33;p12)pat, resulting in a pure partial 5q33-q35 trisomy due to the adjacent-1 segregation of a paternal balanced translocation. Paternal blood karyotype revealed a balanced translocation t(5;14)(q33;p12) retaining Ag-Nors. To date, only two cases of pure partial 5q trisomies spanning this region have been reported. Analysis of these cases and the one we report does not allow the delineation of a specific phenotype.     

Familial t(X;2) (p223;q323) with partial trisomy 2q and male and female balanced carriers

Summary A familial t(X;2) (p223;q323) is responsible for partial trisomy 2q in the proposita, a 3-year-old girl with severe mental retardation and hypotrophia. It is present in the balanced state in the mother, two daughters, and one son. X-replication was studied after BUDR incorporation and acridine organge staining. The reproductive impairment of balanced X/autosome translocations is discussed.     

Balanced autosomal translocations and ovarian dysgenesis

We report two unrelated women with gonadal dysgenesis, and a (6;15)(p21.3;q15) and a (8;9)(p11.2;q12) balanced translocation, respectively. The patients were of normal stature and showed no phenotypic abnormality or malformation other than ovarian failure. We are not aware of other reports of balanced autosomal translocations associated with gonadal dysgenesis in women. The occurrence of chromosome anomaly and sterility in the two females may be coincidental. However, studies on mouse gametic progression indicate that balanced autosomal translocations can cause oocyte degeneration and reduction of reproductive lifespan. On the basis of these observations, we cannot exclude that the ovarian failure in our patients is the result of oocyte degeneration because of as yet unidentified consequences of the balanced translocations.     

De novo balanced translocation (2;10)(q24;q22) associated with mental retardation

We report a case of a reciprocal translocation between the long arms of the 2 and 10 chromosomes observed in a 14-year-old male with mild mental impairment, compulsive and obsessive behavior. The apparently balanced translocation was characterized by fluorescence in situ hybridization and the karyotype was 46, XY, t(2;10)(q24;q22). The way by balanced chromosomal translocations can lead to a disease phenotype are reviewed and discussed.     

Partial trisomy 2q and familial translocation t(2;12)(q31;q24)

Summary Report is given of a boy with trisomy of the distal part of the long arm of chromosome 2 (q31ter) due to a balanced 2/12 translocation in the mother: 46,XX,t(2;12) (q31;q24). Other phenotypically normal carriers of this balanced translocation are the patients sister and grandfather. The patient shows a variety of dysplastic signs mainly of the face.     

Trisomy of the distal 15q region due to familial balanced translocation t(15;16)(q24;p13) and unusual mosaicism in the mother of the proband

Clinic-cytogenetic analysis of the patient with distal 15q trisomy is presented. Proband's mother and grandmother are carriers of the balanced translocation t (15; 16) (q24; p13). Phenotypically normal proband's mother has a second cell clone with repaired marker chromosome 15 which participates in the balanced translocation of the main cell line. It is supposed possible to repair translocated human chromosomes as a result of mitotic recombination process.     

A jumping translocation (5p;15q), (8q;15q), and (12q;15q) (author's transl)]

Three balanced karyotypes (5p;15q), (8q;15q), and (12q;15q) were found simultaneously in a child with the Willi-Prader syndrome. The hypothesis is presented of a "jumping# translocation by affinity of telomeric and interstitial palindromes. The relationship between the Willi-Prader syndrome and a juxtacentric anomaly of the long arm of chromosome 15 is discussed.     

Partial trisomy of distal 5q and partial monosomy of Xp as a result of mating between two translocation carriers: a female with a balanced translocation t(X;5)(p11;q31) and a male with a der(13;14)(q10;q10)--a case report and a family study

This paper presents the family of a dysmorphic child with the phenotypic features of Turner's syndrome and 5q trisomy, whose parents are both carriers of a balanced translocation. The parents' karyotypes are 46,X,t(X;5)(p11.1;q31) and 45,XY,der(13;14)(q10;q10), respectively.     

Nondisjunction of a translocation-chromosome t(4;13)

Summary We have studied a male infant with multiple congenital anomalies due to a double derivative chromosome 13 resulting from an inherited balanced reciprocal translocation t(4;13)(q23;q12).     

Two cases of del(13q)-retinoblastoma and two cases of partial trisomy due to a familial insertion

A del(13)(q13q21.1) was found in a patient with bilateral retinoblastoma and mental retardation. The father was carrier of an ins(16;13)(q12.2;q13q21.1) which also was present in several other family members, and responsible for another case of del (13q)-retinoblastoma and two cases of trisomy for the inserted segment. This second del(13q) patient was also carrier of a balanced t(11;22).     

Two sibs with duplication of 4q31-->qter due to 3:1 meiotic disjunction and mild phenotype

Two sibs with duplication of 4q31-->qter due to 3:1 meiotic disjunction and mild phenotype: Clinical and cytogenetic findings in two sibs with partial duplication of 4q31.3-->qter and 21q11.2-->pter are reported. These patients are rare cases of reoccurrence of those partial trisomies due to 3:1 segregation of a maternal balanced translocation. A review of the literature reporting cases of trisomy of the 4q31-->qter segment is also made; previously reported cases mostly in addition have deletions of other chromosomes resulting from adjacent segregation of balanced translocation. The findings of our study confirm the high risk for offspring with unbalanced rearrangements in women with reciprocal translocation involving acrocentric and short chromosome segments. The study also points out that duplication of 4q31-->qter may go along with only mild phenotypic findings if there is no significant additional aneuploidy of the other chromosome involved in the rearrangement.     

The fetal phenotype of partial trisomy of the long arm of chromosome 4 (4q22----4qter).

A slightly malformed female fetus with partial trisomy 4q due to a maternal balanced translocation t(1;4)(q44;q22) is reported. This fetus presented some of the typical facial features and internal malformations associated with pure partial trisomy 4q indicating that chromosomal diagnosis is needed to confirm the reality of the malformative syndrome.     

Two new cases of trisomy 10q21 to 10qter in two sisters due to paternal translocation t(9;10) (q34;q24)]

Two sisters with multiple congenital malformations were shown to be trisomic for 10q24 to 10qter as a consequence of malsegregation of the balanced paternal translocation t(9;10) (q34;q24). Comparison of their phenotype with that of other patients reported in the literature confirms the individuality of the partial 10q trisomy syndrome.     

Balanced de novo translocation t(6;7)(p25;q31) and cleft palate as an isolated finding

We report a prenatally diagnosed balanced de novo translocation t(6;7)(p25;q31). Physical examination of the baby born at term revealed only a posterior cleft palate. Laboratory examinations and radiologic investigations were found normal. Two years follow-up of the patient showed her mental and motor development was appropriate with her age. Our report is the first observation on balanced de novo translocation t(6;7)(p25;q31) and cleft palate. Association of this translocation and cleft palate has not been reported previously.     

De novo microdeletion on an inherited Robertsonian translocation chromosome: a cause for dysmorphism in the apparently balanced translocation carrier.

Robertsonian translocations are usually ascertained through abnormal children, making proposed phenotypic effects of apparently balanced translocations difficult to study in an unbiased way. From molecular genetic studies, though, some apparently balanced rearrangements are now known to be associated with phenotypic abnormalities resulting from uniparental disomy. Molecular explanations for other cases in which abnormality is seen in a balanced translocation carrier are being sought. In the present paper, an infant is described who has retarded growth, developmental delay, gross muscular hypotonia, slender habitus, frontal bossing, micrognathia, hooked nose, abundant wispy hair, and blue sclerae. Cytogenetically, she appeared to be a carrier of a balanced, paternally derived 14;21 Robertsonian translocation. Analysis of DNA polymorphisms showed that she had no paternal allele at the D14S13 locus (14q32). Study of additional DNA markers within 14q32 revealed that her previously undescribed phenotype results from an interstitial microdeletion within 14q32. Fluorescent in situ hybridization was used to show that this microdeletion had occurred de novo on the Robertsonian translocation chromosome. These observations may reactivate old suspicions of a causal association between Robertsonian translocations and de novo rearrangements in offspring; a systematic search for similar subcytogenetic rearrangements in other families, in which there are phenotypically abnormal children with apparently balanced translocations, may be fruitful. The clinical and molecular genetic data presented also define a new contiguous gene syndrome due to interstitial 14q32 deletion.     

Regional chromosomal localisation of APOA2 to 1q21–1q23

Summary Using in situ hybridisation, we have mapped APOA2 to the 1q21–1q23 region of chromosome 1. DNA hybridisation to somatic cell hybrids made from cells carrying a balanced translocation between X and 1 confirms the localisation as proximal to 1q23. This was further confirmed by the presence of two polymorphic alleles in a cell line carrying a deletion of 1q25–1q32.