Fetus with unbalanced translocation involving chromosomes 2 and 11.

We report a fetus with an unbalanced translocation between chromosomes 2 and 11, the product of a paternal balanced reciprocal translocation, fetal karyotype 46, XX, -11, +der(11)t(2;11) (q35;q24.1)pat. The fetus had unusual facial features. The relevance of this case to mapping of the type I Waardenburg syndrome gene is discussed.     

Cytogenetics of aborters and abortuses

783 aborters and 430 abortuses were studied in a prospective cytogenetic survey which attempted to link chromosome abnormalities and history of recurrent abortion. 425 female and 358 male spontaneous aborters and their 430 abortuses (310 were karotyped) showed 4 women and 2 men as balanced translocation carriers (3 Robertsonian and 3 reciprocal translocations) and a woman with an XXX karotype. 5 of the abortuses were successfully karotyped; 4 had inherited unbalanced translocation products, and the other had a balanced 13q14q translocation plus trisomy 18. Apparently, translocation chromosomes carried by aborters were transmitted to their abortuses. Structural chromosome abnormalities were found with higher frequency (.8%) among aborters than among the general adult population (.3%). Translocation carriers were more frequent among the aborters with histories of recurrent abortions (2.7%) as well as among aborters with a history of perinatal deaths (3.6%) than among those persons with no such histories (.6%). Data on 18 couples whose 2 or 3 successive spontaneous abortuses were karotyped are presented.     

Prenatal diagnosis of a 9q34.3 microdeletion by array-CGH in a fetus with an apparently balanced translocation

OBJECTIVES: Use high-resolution genome analysis to clarify the genomic integrity in a fetus with a cytogenetically balanced translocation t(2;9)(q11.2;q34.3). METHODS: High resolution molecular cytogenetic analyses including G-banded chromosome analysis, fluorescence in situ hybridization (FISH), and array-comparative genomic hybridization (CGH) were performed on cultured cells, and DNA extracted from chorionic villus sample (CVS), amniotic fluid cells and fetal tissue. In addition, a custom fosmid-based tiling path 9q34.3 microarray with a resolution of 35-40 kb was used for array-CGH. RESULTS: GTG-banding analysis showed an apparently balanced de novo translocation between the long arms of chromosomes 2 and 9; t(2;9)(q11.2;q34.3). Array-CGH using a targeted chromosomal microarray analysis (CMA) uncovered a submicroscopic deletion of the subtelomeric region of 9q34.3 revealing the unbalanced nature of the rearrangement. These results were confirmed independently by FISH. The deletion was delimited to 2.7 Mb in size using the 9q34.3 fosmid-based tiling path array-CGH. CONCLUSION: Array-CGH is a powerful tool for rapid detection of genomic imbalances associated with microdeletion/duplication syndromes and for the evaluation of de novo apparently balanced translocation to enable high-resolution genomic analysis at the breakpoints. Prenatal diagnosis of chromosomal rearrangements involving dosage-sensitive genomic regions is an important adjuvant to prenatal care and provides more accurate information for counseling and informed decision making.     

Molecular cytogenetic characterization of de novo concomitant proximal 21q deletion of 21q11.2q21.3 and distal Xp deletion of Xp22.33p22.2 due to an unbalanced X;21 translocation detected by amniocentesis

ObjectiveWe present molecular cytogenetic characterization of de novo concomitant proximal 21q deletion of 21q11.2q21.3 and distal Xp deletion of Xp22.33p22.2 due to an unbalanced X; 21 translocation detected by amniocentesis.Case reportA 35-year-old, primigravid woman underwent amniocentesis at 17 weeks of gestation because of advanced maternal age. Amniocentesis revealed a karyotype of 45,X,der(X)t(X; 21) (p22.2; q21.3),-21. Simultaneous array comparative genomic hybridization (aCGH) revealed the result of an 11.9-Mb Xp22.33p22.2 deletion encompassing HCCS, SHOX, AMELX and OFD1 and a 15.4-Mb 21q11.2q21.3 deletion encompassing NRIP1 and APP. The pregnancy was subsequently terminated, and a malformed fetus was delivered with craniofacial dysmorphism. The parental karyotypes were normal. Polymorphic DNA marker analysis by quantitative fluorescence polymerase chain reaction (QF-PCR) confirmed a paternal origin of the 21q proximal deletion. Cytogenetic analysis of cord blood confirmed the karyotype of 45,X,der(X)t(X; 21) (p22.2; q21.3),-21. aCGH analysis of the cord blood confirmed the prenatal diagnosis.ConclusionQF-PCR analysis is useful for determination of the parental origin of a de novo unbalanced X; autosome translocation detected by prenatal diagnosis. The information acquired is useful for genetic counseling under such a circumstance.     

MLPA as a screening method of aneuploidy and unbalanced chromosomal rearrangements in spontaneous miscarriages

OBJECTIVE: The present study aims to validate multiplex ligation-dependent probe amplification (MLPA) technique with subtelomeric probe mixes as a screening method to detect aneuploidy and unbalanced terminal chromosomal rearrangements in spontaneous abortions (SAs). METHODS: MLPA with P036B and P070 probe mixes was performed on 221 miscarriage DNA samples between the 5th and 24th week of gestation. Cytogenetic culture was attempted on 178 miscarriages. Karyotyped miscarriages served as controls in this blinded study. Results were confirmed by quantitative fluorescent-PCR (QF-PCR). RESULTS: Among the karyotyped miscarriages, MLPA was able to detect all the expected aneuploidies, as well as an unbalanced product from a reciprocal translocation, and revealed cryptic deletions and duplications not visible at the 550-band resolution level. In addition, chromosomal anomalies were found in approximately 37% of cases that failed to grow or could not be cultivated. As expected, ploidy changes were not detected. Copy number variation was found for target sequences of P036B (CYFIP1, MRPL41, CAB45) and P070 (DECR2, TNFRSF18) probe mixes. CONCLUSIONS: We propose the use of MLPA with subtelomeric probe mixes as a reliable, rapid and economical first approach to detect aneuploidy and unbalanced terminal chromosomal rearrangements in SAs.     

Anterior chamber eye anomalies, redundant skin and syndactyly--a new syndrome associated with breakpoints at 2q37.2 and 7q36.3.

We report a 34-year-old female with a de novo balanced reciprocal translocation involving 2q37.2 and 7q36.3. She has a unique combination of multiple congenital malformations that include redundant skin, complete tissue syndactyly of the hands and feet, hirsutism, polycystic ovaries and bilateral anterior chamber eye anomalies. Her son has inherited the unbalanced product (46,XY,der(2) t(2;7)(q37.2;q36.3). He has a similar clinical picture with additional features including complex congenital heart disease, post axial polydactyly, hypotonia and global developmental delay. The breakpoints may indicate the location of the gene(s) responsible for this unique combination of features.     

Chromosomal 10Q26 trisomy resulting from paternal T(9;10)(PTER;Q26.1).

Distal 10q trisomy is a well defined but rare syndrome, and almost always the result of an unbalanced translocation. Clinical evaluation and cytogenetic molecular analyses were performed in a 6-year-old boy with developmental delay and facial dysmorphism including marked blepharophimosis. His karyotype showed an unbalanced translocation between chromosomes 9 and 10, resulting in trisomy of the distal part of the long arm of chromosome 10q26. A balanced translocation of the segment between chromosomes 9 and 10 with breakpoints at 10q26.1 and 9pter or p24.3 was found in his father, who had normal phenotype. Unlike most cases of partial 10q trisomy which have concurrent partial monosomy of one other translocated chromosome, fluorescence in situ hybridization studies revealed this case to be a pure 10q26 trisomy. The translocated 10q segments in most cases of 10q trisomy originate from the father. Imprinting effect may exist in this chromosomal syndrome; distal 10q trisomy from paternal reciprocal translocations is more compatible with life.     

Phenotypic features of a boy with trisomy of 16q22-->qter due to paternal Y; 16 translocation

We report on the phenotypic features of a patient with partial trisomy of the long arm of chromosome 16 due to an unbalanced Y;16 translocation (46,X,der[Y]t[Y;16] [q12;q22]pat). The patient was noted to have craniofacial anomalies and developmental delay, but no other major malformations. The father, a balanced Y;16 translocation carrier, has apparently normal fertility.     

Successful pregnancy after preimplantation genetic diagnosis for carrier of t(2;7)(p11.2;q22) with high rates of unbalanced sperm and embryos: a case report

BACKGROUND: Regarding the literature on the results of preimplantation genetic diagnosis (PGD) in reciprocal chromosomal translocation carriers seems to prevail a view that this method reduces the frequency of miscarriages, and the pregnancy rate is directly proportional to the number of normal spermatozoa. Therefore, we compared the results of sperm karyotype analysis of a carrier of familial t(2;7)(p11.2;q22) with PGD results. The carrier was ascertained as his wife had had two miscarriages. METHODS: Empirical data from a pedigree of t(2;7)(p11.2;q22) carrier was collected. A tri-color fluorescence in situ hybridization method (FISH) was used to show the meiotic segregation pattern in sperm of the proband. PGD of blastomeres from a single ICSI cycle and standard prenatal diagnosis procedures to confirm the PGD results was performed. RESULTS: Meiotic segregation pattern showed only 34.2% of normal/balanced spermatozoa. The high rate (42%) of miscarriages was observed in this family, which could be explained by chromosomal unbalanced karyotypes as a product of fertilization by unbalanced spermatozoa found with a frequency of approximately 66%. The lack of unbalanced progeny at birth suggests a natural selection of unbalanced fetuses. The 37.5% of normal/balanced embryos received after a single ICSI cycle and PGD was similar to the percentage of normal/balanced spermatozoa (34.2%). After 38 weeks a healthy girl with normal karyotype was born. CONCLUSION: The presented study is an optimistic message for translocation carriers showing that even in case with more than 60% of genetically unbalanced sperm there is a reasonable chance for reproductive success.     

Inv dup del(10q): identification by fluorescence in situ hybridization and array comparative genomic hybridization in a fetus with two concurrent chromosomal rearrangements

ObjectiveTo present molecular cytogenetic characterization of an inverted duplication with terminal deletion of 10q, or inv dup del(10q) in a fetus with two concurrent chromosomal rearrangements.Materials, Methods and ResultsA 39-year-old woman underwent amniocentesis at 20 weeks of gestation because of advanced maternal age. Amniocentesis revealed a der(10) with additional material at the end of the long arm of chromosome 10, a der(9) and a der(22). Parental karyotypes were normal. A de novo unbalanced complex chromosomal rearrangement (CCR) was diagnosed by conventional cytogenetics, but the breakpoints could not be defined. The pregnancy was subsequently terminated, and a malformed fetus was delivered with facial dysmorphism. Postnatal analysis of fetal tissues using spectral karyotyping, fluorescence in situ hybridization, multicolor banding, and array-comparative genomic hybridization identified an inv dup del(10q) with an inverted duplication of 10q25.1→q26.2 and a terminal deletion of 10q26.2→qter, and a balanced reciprocal translocation between chromosomes 9 and 22. Microsatellite analysis determined a paternal origin of the inv dup del(10q). The karyotype of the fetus was 46,XX,t(9;22)(p23;q13),der(10)del(10)(q26.2) dup(10)(q26.2q25.1)dn.ConclusionA de novo inv dup del(10q) can be associated with a concurrent de novo balanced reciprocal translocation and should be differentiated from an unbalanced CCR by molecular cytogenetic techniques.     

Six cases of deletion 9p24 and trisomy 19q13.4 inherited from a familial balanced translocation.

The deletion 9p with trisomy 19q syndrome is a rare disorder. We report 2 adults and 4 children with deletion 9p and trisomy 19q due to familial balanced 9p;19q translocation with clinical features suggestive of monosomy 9p. The children had dysmorphic features and psychomotor retardation while the adults were self-sufficient but worked in a sheltered environment. High-resolution chromosome analysis and fluorescence in situ hybridization confirmed that the 6 cases of unbalanced translocation, der(9)t(9;19)(p24.1;q13.4) were inherited from a balanced translocation carrier, t(9;19)(p24.1;q13.4). The dysmorphic features included trigonocephaly, small nose with stunted tip, and long philtrum. Associated anomalies included wide-set nipples, extra finger flexion creases, hernia, external genitalia hypoplasia, scoliosis, and hypopigmented skin patch. We suggest that genetic counseling is necessary for those who have family members with dysmorphic features and/or major anomalies and/or psychomotor retardation.     

Concomitance of 47,XXY,a balanced reciprocal translocation of t(4;17)(q12;q11.2) encompassing SPINK2 at 4q12 and NOS at 17q11.2 and an AZFa sY86 deletion in an infertile male

ObjectiveWe present an infertile male who was incidentally detected to have Klinefelter syndrome, a balanced reciprocal translocation of t(4; 17) (q12; q11.2) and an AZFa sY86 deletion. We review the literature and discuss the significance of 47,XXY, t(4; 17) (q12; q11.2) and AZFa sY86 deletion in this case.Case reportA 37-year-old married infertile male was referred for genetic studies of azoospermia. His height was 195 cm and his weight was 85 kg. He had been married for more than one year without any pregnancy in his wife. He was referred for genetic counseling. Cytogenetic analysis revealed a karyotype of 47,XXY,t(4; 17) (q12; q11.2). In addition to Klinefelter syndrome, a balanced reciprocal translocation and an AZFa microdeletion were found. Sequence analysis of SPINK2 and NOS was also performed. These two fertile related genes were located at the breakpoints of translocation respectively. Heterozygosity of single-nucleotide polymorphisms (SNPs) evidenced the presence of two alleles as well as no deletions occurred at the breakpoint regions. An AZF gene analysis revealed a microdeletion at the region of AZFa sY86 region.ConclusionGenetic analysis of an infertile male may detect multiple factors associated with azoospermia such as translocation, an AZF deletion and Klinefelter syndrome. This case emphasized the importance of tests for chromosomes and AZF deletions among patients with azoospermia. Complete genetic counseling of the consequence of a familial inheritance is also necessary to detect more family carrier members for the prevention of unbalanced chromosome in the offspring.     

Inheritance of imbalances in recurrent chromosomal translocation t(11;22): clarification by PGT-SR and sperm-FISH analysis

Research questionTo analyse why unbalanced viable offspring are derived mainly from the 3:1 segregation mode in t(11;22)(q23;q11.2) reciprocal translocation.DesignRetrospective analysis of 24 pre-implantation genetic testing for chromosomal structural re-arrangements (PGT-SR) cycles was performed on seven male and five female carriers of t(11;22) translocation. Sperm analysis was performed on each male carrier. These patients were directed to the study centre after several years of miscarriages and/or abortions, primary infertility for male carriers or birth of an affected child.ResultsTwenty-four PGT-SR cycles were performed to exclude imbalances in both male and female carriers. The unbalanced embryos derived from the adjacent-1 segregation mode were the most represented in both male and female carriers (68.4% and 50%, respectively). These results were positively related with meiotic segregation analysis of reciprocal translocation in spermatozoa. A thorough analysis of the unbalanced embryo karyotypes determined that the expected viable +der22 karyotype resulting from 3:1 malsegregation was less represented at 5.3%.ConclusionsThese findings highlight the divergence that may exist between meiotic segregation and post-zygotic selection. Post-zygotic selection would be responsible for the elimination of unbalanced embryos derived from the adjacent-1 segregation mode. The combined action of several factors occurs at the beginning of post-zygotic selection. Genetic counselling must consider the risk of a birth related to the adjacent-1 segregation mode, irrespective of the sex of the translocation carrier. These results will allow deeper understanding of the PGT results of t(11;22) carriers, which often include a high number of aneuploid embryos.     

Simultaneous cell by cell study of both DNA fragmentation and chromosomal segregation in spermatozoa from chromosomal rearrangement carriers

Purpose

Balanced chromosomal translocations are found in one out of 500 subjects in the general population. They usually do not carry any phenotypic consequences, except for possible infertility and for the production of unbalanced gametes leading to spontaneous abortions or chromosomal syndromes in the offspring. An association between chromosomal rearrangements and increased apoptosis markers has been demonstrated on a global scale in sperm samples of translocation and inversion carriers. In order to specify which kind of sperm cells is subject to an increased apoptosis process, this present study was aimed to analyse both chromosomal segregation and DNA fragmentation, sperm cell by sperm cell.

Methods

Six patients carrying a chromosomal rearrangement (three reciprocal translocations, two Robertsonian translocations, and one chromosomal pericentric inversion) were included in a retrospective manner. Both DNA fragmentation and chromosomal segregation in spermatozoa were evaluated simultaneously using a modified TUNEL assay associated with FISH. Two thousand spermatozoa were analysed for each patient.

Results

We showed a higher proportion of spermatozoa with fragmented DNA among the unbalanced sperm cells, compared to the balanced ones, in all six patients.

Conclusions

These results suggest an increased fragility of unbalanced spermatozoa to exogenous fragmentation factors. The exact mechanisms of those processes remain to be elucidated.     

Microphthalmia with linear skin defects (MLS) syndrome evaluated by prenatal karyotyping, FISH and array comparative genomic hybridization

OBJECTIVE: To explore the utility of comparative genomic hybridization to BAC arrays (array CGH) for prenatal diagnosis of microphthalmia and linear skin defects syndrome. METHODS: We used karyotype analysis, FISH and array CGH to investigate an X;Y translocation. Replication studies were done on cultured amniocytes and lymphoblasts. RESULTS: We describe a severe case of MLS syndrome that presented prenatally with multiple anomalies including cystic hygroma, microphthalmia, intrauterine growth restriction and a complex congenital heart defect. Cytogenetic analysis of amniocytes revealed an unbalanced de novo translocation between chromosomes X and Y [karyotype 46,X,der(X)t(X;Y)(p22.3;q11.2).ish der(X)(DXZ1+,DMD+,KAL-,STS-,SRY-),22q11.2 (Tuple1 x 2)]. MLS diagnosis was made at birth and the prenatal karyotype was confirmed. Replication studies showed the derivative X chromosome was the inactive X. Array CGH confirmed the X and Y imbalances seen in the karyotype and also showed twelve BACs in the MLS region were deleted as a result of the translocation. FISH with BAC clones verified the array findings and placed the X breakpoint in Xp22.2, resulting in the amended karyotype, 46,X,der(X)t(X;Y)(p22.2;q11.2).ish der(X)(DXZ1+,DMD+,KAL-,STS-,SRY-),22q11.2(Tuple1 x 2) arr cgh Xp22.33p22.2(LLNOYCO3M15D10 -->GS1-590J6)x 1,Yq11.222q23(RP11-20H21-->RP11-79J10)x 1. CONCLUSION: The sensitivity of array CGH was valuable in detecting monosomy of the MLS critical region. Array CGH should be considered for the prenatal diagnosis of this syndrome.     

Unbalanced cryptic translocation der(14)t(9;14)(q34.3;q32.33) identified by subtelomeric FISH

We investigated a girl with dysmorphic features and moderate developmental delay by subtelomeric FISH (fluorescence in-situ hybridization). We found an unbalanced cryptic translocation, t(9;14)(q34.3;q32.33), resulting in a subtelomeric deletion of 14q and duplication of 9q deriving from a balanced translocation in the mother. A review of the literature suggests that the phenotype of our case is related to the 14 qter deletion, without signs of concomitant partial trisomy 9. The case reinforces the value of subtelomeric screening for genetic counselling.     

De novo monosomy 9p24.3-pter and trisomy 17q24.3-qter characterised by microarray comparative genomic hybridisation in a fetus with an increased nuchal translucency

OBJECTIVES: Increased nuchal translucency (NT) during the first trimester of pregnancy is a useful marker to detect chromosomal abnormalities. Here, we report a prenatal case with molecular cytogenetic characterisation of an abnormal derivative chromosome 9 identified through NT. METHODS: Amniocentesis was performed because of an increased NT (4.4 mm) and showed an abnormal de novo 46,XX,add(9)(p24.3) karyotype. To characterise the origin of the small additional material on 9p, we performed a microarray comparative genomic hybridisation (microarray CGH) using a genomic DNA array providing an average of 1 Mb resolution. RESULTS: Microarray CGH showed a deletion of distal 9p and a trisomy of distal 17q. These results were confirmed by FISH analyses. Microarray CGH provided accurate information on the breakpoint regions and the size of both distal 9p deletion and distal 17q trisomy. The fetus was therefore a carrier of a de novo derivative chromosome 9 arising from a t(9;17)(p24.3;q24.3) translocation and generating a monosomy 9p24.3-pter and a trisomy 17q24.3-qter. CONCLUSION: This case illustrates that microarray CGH is a rapid, powerful and sensitive technology to identify small de novo unbalanced chromosomal abnormalities and can be applied in prenatal diagnosis.     

Semilobar holoprosencephaly prenatal diagnosis: an unexpected complex rearrangement in a de novo apparently balanced reciprocal translocation on karyotype

We report a semilobar holoprosencephaly (HPE) in a post-intracytoplasmic-sperm-injection pregnancy. It was suggested by ultrasonography (US), documented on karyotype, identified with magnetic resonance imaging (MRI), established after birth and confirmed on post-mortem autopsy. An amniocentesis revealed a de novo apparently balanced reciprocal translocation 46,XY, t(7;8) (q31.3;q12). Fluorescence in situ hybridization (FISH) identified a deletion in the region of the Sonic Hedgehog gene (SHH) on der(8); nevertheless, the subtelomeric regions for chromosomes 7 and 8 were present. The parents decided to continue the pregnancy; a boy was born and survived for 3 days. The brain autopsy confirmed the semilobar HPE previously noted on US and MRI. Further, band-specific FISH revealed, in addition to SHH deletion, the presence of an inversion in the 7q translocated material on der(8). The parents' karyotypes were normal. An unexpected complex rearrangement was present in a de novo apparently balanced reciprocal translocation in a semilobar HPE.     

Cytogenetic studies in couples with repeated spontaneous abortions

Chromosome studies were carried out on both partners of 509 couples with a history of two or more spontaneous abortions. 1) Twenty-six individuals (2.6%) were carriers of a major chromosome abnormality. This incidence is at least six to seven times higher than that in the general adult population. 2) Of these, 10 were reciprocal translocations, 10 robertsonian translocations and 6 numerical aberrations of gonosomes. None of the carriers showed abnormal phenotypes. 3) Chromosome aberrations were more frequent in the women than in their husbands. There were 19 abnormalities in females and 7 in males. 4) The use of banding techniques in chromosome analysis improves the detection of balanced reciprocal translocations. 5) Prenatal diagnosis was performed in 5 subsequent pregnancies of 4 balanced translocation carriers. The fetal karyotypes were 2 normal and 3 balanced translocations. It would seem reasonable to recommend chromosome analysis for couples with repeated spontaneous abortions.     

Cytogenetic analysis of trophoblasts by comparative genomic hybridization in embryo-fetal development anomalies

Cytogenetic studies of spontaneous abortions or intrauterine fetal death depend on conventional tissue culturing and karyotyping. This technique has limitations such as culture failure and selective growth of maternal cells. Fluorescent in situ hybridization (FISH) using specific probes permits diagnosis of aneuploidies but is limited to one or a few chromosomal regions. Comparative genomic hybridization (CGH) provides an overview of chromosomal gains and losses in a single hybridization directly from DNA samples. In a prospective study, we analyzed by CGH trophoblast cells from 21 fetuses in cases of spontaneous abortions, intrauterine fetal death or polymalformed syndrome. Six numerical chromosomal abnormalities including one trisomy 7, one trisomy 10, three trisomies 18, one trisomy 21 and one monosomy X have been correctly identified by CGH. One structural abnormality of the long arm of chromosome 1 has been characterized by CGH. One triploidy and two balanced pericentromeric inversions of chromosome 9 have not been identified by CGH. Sexual chromosomal constitutions were concordant by both classical cytogenetic technique and CGH. Contribution of trophoblast analysis by CGH in embryo-fetal development anomalies is discussed.