Prenatal diagnosis of a homologous Robertsonian translocation involving chromosome 15

We report the prenatal diagnosis of a fetus with a de novo Robertsonian translocation: 45,XY,der(15;15)(q10;q10). Although Robertsonian translocations are common chromosomal rearrangements, those involving homologous chromosomes are infrequent. Since chromosome 15 is imprinted, uniparental disomy (UPD) is a concern when chromosomal rearrangements involving chromosome 15 are identified. In the present case, UPD studies showed normal biparental inheritance. In contrast to the fact that most homologous acrocentric rearrangements are isochromosomes, these results indicate postzygotic formation of a Robertsonian translocation between biparentally inherited chromosomes 15.     

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.     

Prevalence of chromosomal aberrations in Mexican women with primary amenorrhoea

Primary amenorrhoea refers to the absence of menarche by the age of 16-18 years in the presence of secondary sexual characteristics, and occurs in 1-3% of women of reproductive age. To study the prevalence of chromosomal abnormalities and the different options available for clinical management of women in Mexico with primary amenorrhoea, a cross-sectional study was conducted in 187 women with primary amenorrhoea referred from Department of Reproductive Medicine of Morones Prieto Hospital, IMSS in Monterrey, Mexico during 1995-2003. Peripheral blood lymphocytes were cultured for chromosomal studies by the standard methods. Numerical or structural abnormalities of the sex chromosome were found in 78 women (41.71%). These women were classified into four categories: X-chromosome aneuploidies (22.99%: 12.83% pure line and 10.16% mosaicism association with a 45, X cell line); presence of chromosome Y (10.70%); structural anomalies of the X chromosome (4.28%); and marker chromosomes (3.74%). In conclusion, the prevalence of chromosomal abnormalities in Mexican women with primary amenorrhoea is within the range (24-46%) reported in world literature. Chromosomal analysis is absolutely necessary for appropriate clinical management of these patients.     

A family study of complex chromosome rearrangement involving chromosomes 1, 8, and 11 and its reproductive consequences

Complex chromosome translocations are structural chromosomal rearrangements involving three or more chromosomes and more than two breakpoints. A complex chromosome rearrangement was detected in a phenotypically normal female patient that was referred to the hospital for genetic counseling due to reproductive failure. A cytogenetic evaluation was performed, according to standard method of chromosomal analysis, using G-banding technique. The patient’s karyotype showed a balanced complex chromosome rearrangement (BCCR) involving chromosomes 1, 8, and 11 with three breakpoints 1p31, 8q13, and 11q23. The karyotype designed according to ISCN (2013), is 46,XX,t(1;8;11)(p31;q13;q23) (8qter→8q13::1p31→1qter;8pter→8q13::11q23→11qter;11pter→11q23::1p31→1pter). Additionally, the proband’s mother and brother were tested, resulting in the same exact translocation. In this study, we describe all possible meiotic segregations regarding this translocation, as well as the clinical phenotypes which could arise, if unbalanced products of conception survive. This is a rare case of familial complex chromosome rearrangement, giving a view for its reproductive consequences.     

Cytogenetic analysis of 179 Iranian women with premature ovarian failure

Abstract

The importance of chromosomal abnormalities in etiology of premature ovarian failure (POF) is well known but in many cases, POF still remains idiopathic. We investigated the frequency and type of chromosomal aberrations in Iranian women diagnosed with idiopathic POF. Standard cytogenetic analysis was carried out in a total of 179 patients. Karyotype analysis of these patients revealed that 161 (89.95%) patients had normal female karyotype and 18 (10.05%) patients had abnormal karyotypes. The abnormal karyotypes included sex reverse sex determining region Y (SRY) negative (five Cases), X chromosome mosaicism (five cases), abnormal X chromosomes (three cases), abnormal autosomes (three cases) and X-autosome translocation (two cases). The overall prevalence of chromosomal abnormalities was 10.05% in this first large-scale report of chromosomal aberrations in Iranian women with POF. The results confirm previous observations and emphasis on the critical role of X chromosome abnormalities as one of the possible etiologies for POF.     

Polkörperdiagnostik bei zytogenetischer Prädisposition

Polar body diagnosis (PBD) enables the indirect cyto- and molecular genetic analysis of oocytes. Its main application is the detection of chromosomal aneuploidies in oocytes. In this article, we present our investigations on the use of PBD in cases with a known cytogenetic predisposition. Our data show that the application of PBD is beneficial for maternal translocations as the majority of oocytes are unbalanced for the chromosomes involved in the translocation. The exclusion of aneuploid oocytes results in acceptable pregnancy and delivery rates. Our data on women with low level sex chromosome mosaicism in peripheral lymphocytes are equally interesting. Gonosomal aneuploidies were not found to contribute predominantly to the chromosomal disorders identified in mature oocytes in these patients.     

Terminal 14q deletion with unbalanced t(Y;14)(q12;q32) translocation

Terminal deletions of chromosome 14q are very rarely reported. Schneider et al. (2008) reviewed about 20 cases of 14q32 region deletion in a previous article and only three of the cases involved autosomal translocations; however, no sex chromosome translocations were reported. Here we report the clinical findings of a patient with terminal 14q32 deletion derivated from at (Y;14)(q12;q32) translocation.     

Balanced autosomal translocation and double Robertsonian translocation in cases of primary amenorrhea in an Indian population

ObjectiveTo assess the frequency of balanced autosomal translocations in patients with primary amenorrhea in an Indian population.MethodsCytogenetic analysis was carried out among women referred from all parts of India for primary amenorrhea between 2002 and 2010. Clinical history and laboratory findings were taken into consideration to determine the diagnosis. G-banding with trypsin–Giemsa was performed to detect chromosome abnormalities.ResultsThere were 15 balanced autosomal translocations in 1100 patients. Two novel translocations were identified: 1 with mosaic pattern of X chromosome monosomy and male karyotype, together with balanced autosomal translocation of chromosomes 11 and 20 in both cell lines; and 1 with double Robertsonian translocation of chromosomes 14 and 21.ConclusionAutosomal genes have a crucial role in reproductive development. More candidate genes need to be recognized for appropriate genetic counseling and clinical management.     

Chromosomal translocations and semen quality: A study on 144 male translocation carriers

Research question

Chromosomal translocations are known genetic causes of male infertility. Are certain translocations or chromosomal regions more directly associated with sperm defects? Is there a threshold of sperm impairment that can be relevant for detection of translocations?

Hypoplastic external genitalia in association with X;autosome chromosome translocation.

STUDY OBJECTIVE: To learn the relationship between X;autosome chromosome translocation and hypoplastic external genitalia. BACKGROUND: An X;autosome translocation usually presents with phenotypic features similar to Turner syndrome. PARTICIPANTS: We present three female siblings and their mother with X;autosome translocation and hypoplastic external genitalia. METHODS: Case presentation. RESULTS: Three female siblings, ages 14, 16, and 18 years, presented for routine checkup. All had been seen in the past for short stature, learning disability, and other features similar to those seen in Turner syndrome. At time of presentation, all three had primary amenorrhea. On genital exam, each was found to have hypoplastic external genitalia with absent clitoris and labia minora. Pelvic ultrasound in all subjects showed normal but prepubertal uterus and ovaries. Two subjects have unbalanced translocations with karyotype 46,X,der(9)t(9;X)(q11.2;q22.3). This abnormal chromosome complement results in the loss of the short arm of the X chromosome and the gain of an extra copy of the long arm of chromosome 9. The third subject and her mother have balanced translocations with the karyotype 46,X,t(9;X)(q11.2;q22.3). X-inactivation studies showed skewed inactivation of the normal X chromosome in the balanced translocation carriers, while the two girls with the unbalanced karyotype had skewed inactivation of the translocation product. All subjects have growth hormone deficiency. The oldest sibling was able to menstruate regularly after estrogen/progesterone therapy. The other two patients are currently receiving growth hormone and are gaining height. CONCLUSION: X;autosome translocations may be associated with hypoplastic external genitalia but normal internal genitalia. Balanced carriers can be fertile. To our knowledge, the presence of hypoplastic external genitalia in association with X;autosome translocation has not been previously reported. This should be added to the possible causes of hypoplastic external genitalia.     

Fetal blood chromosome analysis: some new indications for prenatal karyotyping

Prenatal karyotyping using stimulated fetal blood lymphocytes was undertaken in 170 pregnancies between 16 and 36 weeks gestation for the following reasons--mosaicism or marker chromosomes found in amniotic fluid culture; a family history of X-linked mental retardation with fragile Xq28; fetal abnormalities detected ultrasonographically; late booking or amniotic fluid culture failure in patients with advanced age or balanced translocations; and twin pregnancies discordant for a chromosomal anomaly. Forty-one karyotypic abnormalities were detected (24%). These were: 45,X (7 cases), trisomy 13 (5 cases), trisomy 18 (6 cases), trisomy 21 (4 cases), twin pregnancy where one twin had trisomy 21 (1 case), supernumerary marker chromosome (3 cases, one of which occurred in a twin pregnancy), triploidy (3 cases), X-linked mental retardation with fragile site at Xq28 in males (6 cases), fetal erythroleukaemia (3 cases including 2 cases with Turner's), Fanconi's anaemia (1 case), unbalanced chromosome translocation 47,XY+der22,t(11;22) mat (1 case), mos 46,XX18p-/46,XX,-18+i(18q) (1 case), 46,XXdel(2q) (1 case), and 46,XYt(5;17) de novo (1 case). In fetuses at high risk of a chromosome aberration, a rapidly obtained karyotype is helpful and fetoscopy and fetal blood sampling are justified in the second or third trimester.     

Ovarian stimulation in a woman with premature ovarian failure and X-autosome translocation. A case report

BACKGROUND: There are only a few reports on ovulation induction in women with premature ovarian failure resulting from an X chromosome abnormality. Up to now, there have been no publications on ovulation stimulation in a patient with an X-autosome translocation. CASE: A healthy, 29-year-old woman had premature ovarian failure (POF) but no other discernible pathologic clinical features. Laboratory tests prior to initiating a stimulation cycle revealed a 46,XX t(X;16) karyotype. Genetic counseling was proposed, and the risk of X chromosome abnormality was discussed. The couple decided to undergo ovulation induction. For treatment of infertility, clomiphene citrate had been administered in the past. Because those treatments were not successful, GnRH-a and follicle stimulating hormone treatment was recommended. The first treatment cycle was successful in inducing ovulation, but on the 15th day after human chorionic gonadotropin administration, menstruation occurred. The couple refused a second stimulation, and menstruation occurred 32 days after the first. The patient then became amenorrheic again. CONCLUSION: At least some hope can be offered to infertile women with hypergonadotropinism and X-autosomal translocation, although it is impossible to determine whether ovulation induction will result in pregnancy. New treatments can be anticipated for women with POF and X chromosome aberrations who have similar hormonal environments.     

Two unusual chromosome aberrations ascertained by sonographic anomalies

We describe two cases of sonographic abnormalities associated with unusual chromosomal aberrations. Case 1 presented with a cystic hygroma at 12 weeks' gestation. Cytogenetic analysis revealed an unbalanced complex chromosome rearrangement implicating chromosomes 6, 13 and 21 (karyotype: 47,XX,t(6;21;14)(q14;q21;q21)mat,+21) and corresponding to a complete trisomy 21. This anomaly resulted from malsegregation of a maternal balanced three-way translocation. For case 2, an alobar holoprosencephaly was identified by ultrasonography at 23 weeks' gestation. Chromosomal analysis showed a recombinant rec (13), dup q chromosome, secondary to unequal crossing-over of a paternal pericentric inversion of chromosome 13, giving rise to partial trisomy 13q (karyotype: 46,XX,rec(13)dup(13q)inv(13)(p11q21)pat). These two cases illustrate the role of ultrasound in leading to detection not only of foetal chromosomal aberrations but also of rare balanced chromosomal rearrangements presented by one of the two parents.     

Uniparental disomy in fetuses diagnosed with balanced Robertsonian translocations: risk estimate

Forty-two fetuses with non-homologous Robertsonian translocations were analyzed for uniparental disomy (UPD). One fetus with a de novo translocation t(13q;14q) had maternal isodisomy of chromosome 14. In a summary of the published data (including the present study), 315 cases were analyzed for UPD after prenatal diagnosis of balanced Robertsonian translocations, of these two fetuses had UPD, giving a risk estimate of 0.65% (CI 0.2-2.3). This risk justifies the recommendation of UPD analysis in fetuses diagnosed prenatally with Robertsonian translocations, with the emphasis on the chromosomes known to contain imprinted genes, such as 14 and 15. We also discuss the possibility of UPD in offspring of Robertsonian translocation carriers with normal karyotype. Based on the risk for UPD in fetuses with Robertsonian translocation we suggest to test these fetuses for UPD and to do so on amniocytes rather than chorionic villi when the risk for unbalanced karyotype is approximately 1%, comparable to the risk for UPD.     

Spontaneous Abortions Are Reduced After Preconception Diagnosis of Translocations

Purpose: Preimplantation genetic diagnosis of translocations has seldom been attempted. Recently, a genetic test based on analyzing polar bodies at the methaphase stage, following fluorescent in situ hybridization with commercially available whole-chromosome painting DNA probes has been presented. Here we report the use of this method in seven couples in whom the female was a carrier of one of these balanced translocations: 45,XX,der (13q;14q)(q10;q10) (two cases), 46,XX,t(4;14)(p15.3;q24), 45,XX,der(14q;21q) (q10;q10), 46,XX,t(7;20)(q22;q11.2), 46,XX,t(9,11)(p24;q12), 46,XX,t(14;18)(q22;q11), and 46,XX,t(3;8)(q11;;q11). Methods: The original method was improved in two ways. First, centromeric probes for one or both chromosomes involved in the translocation were added to avoid misdiagnosis caused by possible confusion of first polar body monovalent chromosomes (with two chromatids each) with single chromatids. Second, for cases with terminal translocations where commercially available probes do not cover telomere sequences, a telomere probe labeling the translocated fragment was added. Results: A total of 26 abnormal, 18 balanced, and 22 normal eggs was detected. Nine normal and seven balanced embryos were transferred, resulting in eight (50%) implanting, of which one spontaneously aborted. To date, the remainder have produced karyotypically normal or balanced babies and ongoing pregnancies. The rate of spontaneous abortions after preimplantation genetic diagnosis (12.5%) was significantly reduced (P < 0.001) compared to natural cycles in the same patients (95%). Conclusions: With the above improvements, the test can characterize any translocation of maternal origin and produce a high pregnancy rate and an apparently low frequency of spontaneous abortion.     

Prenatal UPD testing survey in Robertsonian translocations

A systematic search was made for uniparental disomy (UPD) in familial or de novo balanced Robertsonian translocations, identified by prenatal cytogenetic investigations. Parent-of-origin studies were performed using molecular markers for both chromosomes involved in the translocation. No UPD cases were identified out of 23 analysed cases. The results presented here, combined with other available data, provide preliminary elements for genetic counselling in these common chromosomal rearrangements.     

Rapid prenatal diagnosis of trisomy 21 in 5049 consecutive uncultured amniotic fluid samples by fluorescence in situ hybridisation (FISH).

OBJECTIVES: This was a retrospective study on the results of interphase fluorescence in situ hybridization (FISH), performed routinely for chromosome 21 and on ultrasonographic indications for chromosomes 13, 18, X and Y in a series of 5049 amniotic fluid samples. METHODS: Interphase FISH for chromosome 21 was performed in 5049 consecutive amniotic fluid samples for the rapid prenatal diagnosis of Down syndrome. Aneuploidy for four other chromosomes (13, 18, X and Y) was tested following ultrasonographic indications. Karyotypes from standard cytogenetic analysis were compared to the FISH results. RESULTS: Using conventional cytogenetics 3.6% (183/5049) chromosomal anomalies were detected. After exclusion of familial chromosome rearrangements, i.e. balanced autosomal reciprocal or Robertsonian translocations (30/5049) and inversions (19/5049), 2.65% chromosomal anomalies (134/5049) were diagnosed. Of this group 0.18% (9/5049) were chromosomal rearrangements not detectable by FISH and 2.47% (125/5049) were numerical chromosomal anomalies detectable by interphase FISH for chromosomes 13, 18, 21, X and Y. With routine interphase FISH for chromosome 21 and FISH on echographic indication for the other four chromosomes we detected 107/125 of these numerical chromosomal anomalies, i.e. 85.6%. All 70 cases of trisomy 21 were detected by FISH and confirmed with conventional cytogenetics (sensitivity=100%) and there were no false-positive results (specificity=100%). Maternal cell contamination of amniotic fluid samples occurred in 1.27% (64/5049) of samples; 0.26% (13/5049) of these samples were uninformative by FISH due to maternal cell contamination (12/5049) or absence of nuclei in one sample (1/5049). CONCLUSION: In this group of 5049 samples we found that FISH is a reliable technique for the rapid prenatal diagnosis of trisomy 21. The number of uninformative cases due to maternal cell contamination was low. The strategy to perform FISH for chromosome 21 in all samples and only on ultrasonographic indication for the four other chromosomes (13, 18, X and Y) followed by standard cytogenetics is effective.     

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.     

Primary Amenorrhoea in a Triple X Female

The incidence of trisomy X in the newborn population is estimated to be 1 in 1,000 liveborn females. Most of them have normal physical appearance and puberty. Therefore, the reported number of triple X females in the literature is low. We herein report one patient with triple X chromosomes, primary amenorrhoea and normal intelligence. Steroid hormonal levels, clinical and ultrasound findings were suggestive of ovarian failure/gonadal dysgenesis. This case emphasizes the need for chromosomal analysis in women presenting with premature ovarian failure leading to primary or secondary amenorrhoea.     

Recurrent pregnancy losses and parental chromosome abnormalities: a review

Summary. A compilation of the cytogenetic results taken from 79 published surveys of couples with two or more pregnancy losses (comprising 8208 women and 7834 men) showed an overall prevalence of major chromosome abnormalities of 2.9%. This is five to six times higher than that of the general adult population. In every group of chromosome abnormalities in the parents a predominance of female to male affected was noted (2:1). Approximately 50% of all chromosome abnormalities detected were balanced reciprocal translocations, 24% were Robertsonian translocations, 12% were sex chromosomal mosaicisms in females, and the rest consisted of inversions and other sporadic abnormalities. Parents with two or more idiopathic pregnancy losses should be karyotyped to aid in management and counselling. When a translocation or other abnormality (e.g. X chromosomal mosaicism) predisposing to an abnormal zygote is found, prenatal diagnosis is indicated in future pregnancies. Even when parental karyotypes are normal, prenatal diagnosis should be considered in subsequent pregnancies of parents with two or more pregnancy losses because of the high incidence of chromosome abnormalities in spontaneous abortions. For the same reason, if a single previous pregnancy loss is known to have been chromosomally aneuploid, parental karyotypes may have to be examined (depending upon the finding in the pregnancy loss), and prenatal diagnosis should also be considered in subsequent pregnancies.