Cytogenetics of recurrent abortions

Chromosome banding studies were carried out on both partners of 37 couples who had had two or more spontaneous abortions. Three patients had chromosome disorders; one was a triple-X female and the other two (one male and one female) were t(13;14) translocation carriers. Review of the literature indicates that the over-all frequency of major chromosome disorders in couples with repeated abortions is 2.6%. About three-fourths of these disorders are reciprocal and Robersonian translocations.     

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.     

309对早期自然流产夫妇的染色体分析——附4例世界首报核型

目的 :分析早期自然流产与染色体异常核型的关系。方法 :检测 30 9对早期自然流产夫妇双方的外周血淋巴细胞染色体核型。结果 :早期自然流产夫妇中异常核型检出率明显高于普通人群 ,总检出率为 6 .95 %。染色体异常 2 0例 :其中平衡易位 18例 (4例为世界首报核型 ) ,增加额外小染色体 2例 ;染色体异态 2 3例 :9号染色体臂间倒位 7例 ,D、G组随体变异 2例 ,9、16号次缢痕异染色质区变异 2例 ,Y染色体异态 12例。结论 :染色体异常和异态是导致早期自然流产的重要原因之一 ,对早期自然流产夫妇进行染色体检查是必要的 ,可以寻找流产原因 ,为优生优育提供依据     

Cytogenetic study in 50 couples with recurrent abortions

The presence of chromosome abnormalities in couples with repeated spontaneous abortion is known even if the phenomenon is far from a complete assessment. A cytogenetic investigation in 50 couples with a history of two or more spontaneous abortions is referred to in this study. A peripheral blood lymphocyte culture was harvested for each subject and the slides were stained by G- and C-banding. Of the 100 individuals examined, 4 were carriers of balanced translocations, 3 of which were of the Robertsonian type. A chromosomal fragility (chromatidic and/or chromosomic gaps) was seen in 2 cases. The incidence of balanced translocations found here is 8% which is near to the mode (about 9%) observed in previous studies. Those frequencies are greater than in the general population (0.1-0.4%). This indicates that balanced translocations have some importance in causing abortion while this is not the case for other chromosomal abnormalities (e.g. pericentric inversions). Thus, cytogenetic analyses should be recommended in couples with repeated spontaneous abortions, when clinical data fail to clarify the cause.     

502对反复自然流产夫妇的染色体研究

对反复自然流产２次或２次以上的５０２对夫妇进行外周血培养Ｇ显带染色体核型分析。发现异常核型５２例，占５．１８％；其中平衡易位３８例，占７３．０８％；染色体数目异常５例，占９．６２％；嵌合体８例，占１５．３８％；９号染色体臂间倒位１例，占１．９２％。结果表明，平衡易位携带者是反复自然流产夫妇中最常见的染色体异常，故流产史是检出人群中平衡易位携带者的重要临床指征。     

染色体平衡易位携带者妊娠风险及妊娠结局的研究

目的 探讨染色体平衡易位携带者的妊娠风险及其妊娠结局.方法 194例染色体平衡易位携带者,根据平衡易位种类分成相互易位（135例）、非同源罗伯逊易位（52例）、同源罗伯逊易位（7例）3组.调查携带者生育史并随访诊断平衡易位后的妊娠情况,比较各组自然流产、先天缺陷及正常（或）平衡易位后代概率.结果 （1）194对夫妇共妊娠503例次,其中自然流产411例次（81.7%,411/503）;产前诊断胎儿异常而终止妊娠16例次（3.2%,16/503）;活产缺陷儿36例次（7.2%,36/503）;正常（或）平衡易位后代40例次（8.0%,40/503）.（2）相互易位、非同源罗伯逊易位、同源罗伯逊易位3组,活产缺陷儿比率分别为5.7%（20/350）、10.9%（14/128）、8.0%（2/25）,3组间相互比较,差异有统计学意义（P＜0.05）;3组正常（或）平衡易位后代比率分别为6.6%（23/350）、13.3%（17/128）、0,3组间相互比较,差异有统计学意义（P＜0.05）;而3组自然流产及产前诊断胎儿异常终止妊娠比率比较,差异无统计学意义（P＞0.05）.（3）52例次先天缺陷中活产36例次（69%）,经产前诊断确诊后引产16例次（31%）.27例次先天缺陷获得细胞遗传学诊断,唐氏综合征发生率为59%（16/27）.（4）相互易位组和非同源罗伯逊易位组共有39对夫妇得到40个正常（或）平衡易位后代,同源罗伯逊易位组无正常（或）平衡易位后代.40个正常（或）平衡易位后代中26个获得产前细胞遗传学诊断,正常核型6个（23%）,平衡易位核型20个（77%）.结论 染色体平衡易位携带者自然妊娠风险大,尤其同源罗伯逊易位携带者难以获得染色体正常（或）平衡易位的后代.     

Chromosome study of couples with repeated spontaneous abortions

The incidence of chromosomal abnormalities was evaluated in couples with a history of repeated abortions. The study included 14 couples with a history of 2 or more spontaneous abortions. Chromosome analysis was carried out on both marital partners from peripheral lymphocyte cultures. In every case, 30-62 metaphases were counted, and at last 20 karyotyped. Among the 14 couples, chromosome anomaly was found in 1 of the partners in 1 case. The patient, a 29-year-old female, was admitted to the hospital in the 36th week of her 10th pregnancy. In addition to an induced abortion and a premature delivery, her history included 7 spontaneous abortions at the 1st or 2nd month. Chromosome analysis of her peripheral blood revealed neither numerical nor structural aberations. In the 38th week, the patient gave birth ato a 3990 gm healthy boy whose karyotype of the cord blood also proved to be normal. The karyotype of the patient's husband revealed 45 chromosomes in 32 observed cells, and a chromosome was missing from each of the D and G groups. It was not possible to include in any of the groups a medium-sized, subterminal chromosome, diagnosed as D/G translocation. The husband proved to be a balanced D/G translocation carrier. When the pedigree was prepared, it was found that the younger sister of the husband had given birth to a child 1 month before term. Both the sister and her child were studied. The sister proved to be a balanced D/G translocation carrier. The child had translocational Down's syndrome: the D/G translocation occured in an unbalanced form. A table lists the results of chromosome investigations of cases of repeated abortions. Of 1066 married partners, chromosome aberations or variations responsible for multiple abortions were found in 70 (6.5%). Of these, 26 proved to be translocations. This incidence, 2-4%, is higher than the .4% in the general population. The results add credence to the argument that chromosome aberation may play a role in the causal background of recurring abortions. It is possible that with special staining procedures some aberations can be demonstrated in cases hitherto considered normal. In cases of repeated abortion, cytogenetic examination of both partners is routinely justified. In cases of chromosome aberations valuable data can be gained to serve as a basis for genetic counseling. When examining women with recurrent abortions, it should be possible to select patients to whom the possibility of intrauterine cytogenetic diagnosis can be offered.     

Zytogenetische Diagnostik

Cytogenetic diagnostics plays a crucial role in human genetics. Although today it appears to have become substituted by modern techniques, such as molecular karyotyping, it remains the basic diagnostic approach for many questions in obstetrics and gynecology. Chromosome aberrations are the reason for approximately 50% of spontaneous abortions and balanced translocations can be found in approximately 5% of couples with recurrent abortions. Moreover, cytogenetics remains the only technique routinely applied for nondirectional whole genome analyses in prenatal diagnostics. An understanding of not only the technique, its potential, and limitations, but also a profound knowledge of the nature of detectable cytogenetic aberrations, their clinical consequences, and recurrence risks are necessary for appropriate counseling of the patients.     

Chromosome abnormalities in 118 couples with recurrent spontaneous abortions

Cytogenetic studies were carried out on 118 couples with recurrent spontaneous abortions. Four major chromosomal abnormalities were found including two 13/14 Robertsonian translocations, one t(7;12) and one t(1;10) reciprocal translocation. The incidence of chromosomal abnormalities in this study was 3.39%, which is lower than the mean value of the published data. The clinical significance of balanced translocations in recurrent reproductive loss is discussed.     

Cytogenetic studies in infertility]

10 TO 15% of all married couples are undesired childless. New investigations show the tendency of a wider increase. Infertility is a possibility caused chromosomaly. In married couples carriers of balanced translocations causing repeated spontaneous abortions in a rate of ten times more than in the normal population. Every 50 married partner is a carrier. Chromosomal cause of infertility should be excluded before an operative therapy is planed and gives a base for genetic counseling.     

Cytogenetic study of peripheral lymphocyte culture in couples with habitual abortion

We report on a cytogenetic investigation of lymphocytes in 241 couples and six women with at least three abortions. We found a balanced reciprocal translocation three times (1.2% of couples) and a balanced Robertsonian translocation twice (0.8% of couples). Four numerical aberrations of the gonosomes were detected (three of them as a mosaic), and one deletion Xq- as a mosaic. The heterochromatic region of the chromosomes 1, 9 or 16 was enlarged in 12 couples (4.9%). There was no couple with a pericentric inversion of the chromosomes 1 or 9. The enlarged Y-chromosome (five males) according to our results does not play any important role for the reproduction. Five translocations and one supernumerary chromosome each in one cell only indicate an enlarged frequency of breakage events in couples with habitual abortion.     

Natural selection between day 3 and day 5/6 PGD embryos in couples with reciprocal or Robertsonian translocations

Purpose

For translocation carriers, preimplantation genetic diagnosis (PGD) provides the opportunity to distinguish between normal/balanced and unbalanced embryos prior to implantation and, as such, increases the likelihood of a successful ongoing pregnancy. The data presented here compares autosomal reciprocal and Robertsonian translocation segregation patterns in day 3 versus day 5/6 IVF-PGD embryos to determine if there is a difference in the chromosome segregation patterns observed at these developmental time points.

Methods

A retrospective analysis on PGD translocation carriers at Monash IVF was performed. Segregation patterns were compared between day 3 and day 5/6 embryos to ascertain whether selection against malsegregants exists.

Results

For reciprocal translocations, 1649 day 3 embryos (139 translocations) from 144 couples and 128 day 5/6 embryos (59 translocations) from 60 couples were analysed. Day 3 segregation analysis showed that 22.3% of embryos were normal/balanced (consistent with 2:2 alternate segregation) and 77.7% were unbalanced (malsegregation). Day 5/6 segregation analysis showed that 53.1% of embryos were normal/balanced and 46.9% were unbalanced. For Robertsonian translocations, 847 day 3 embryos (8 translocations) from 54 couples and 193 day 5/6 embryos (6 translocations) from 31 couples were analysed. Day 3 segregation analysis showed that 38.7% of embryos were normal/balanced (consistent with 2:1 alternate segregation) and 61.3% were unbalanced. Day 5/6 segregation analysis showed that 74.1% of embryos were normal/balanced and 25.9% were unbalanced.

Conclusions

This data demonstrates an increase in the proportion of genetically normal/balanced embryos at day 5/6 of development. This suggests a strong natural selection process between day 3 and day 5/6 in favour of normal/balanced embryos. These findings support performing PGD testing on day 5/6 of embryo development.

     

Chromosomal aberrations in 2000 couples of Indian ethnicity with reproductive failure

Constitutional chromosomal aberrations contribute to infertility and repeated miscarriage leading to reproductive failure in couples. These aberrations may show no obvious clinical manifestations and remain undetected across multiple generations. However, infertility or recurrent spontaneous pregnancy loss, and/or genotypic/phenotypic aberrations may be manifested in the progeny during gametogenesis. The current study was a retrospective analysis to examine the chromosomal aberrations and prevalence in 2000 couples of Indian ethnicity with reproductive failure. Cytogenetic analysis via conventional G-band karyotyping analysis was carried out on phytohaemagglutinin stimulated peripheral blood lymphocytes, cultured in RPMI1640 medium. The chromosomes were enumerated as per International System for Human Cytogenetic Nomenclature at 500–550 band resolution, and recorded in the screening sheets. Chromosomal aberrations were detected in a total of 110 (2.78%) couples, with structural chromosomal aberrations in 88 cases including reciprocal translocations in 56 cases, Robertsonian translocations in 16 cases, inversions in eight cases, deletions in three cases, derivative chromosomes in five cases and numerical chromosome aberrations in 23 cases. The study emphasizes the importance of cytogenetic work up in both the partners associated with a history of reproductive failure. Genetic counselling with an option of prenatal diagnosis should be offered to couples with chromosomal aberrations.Alteration in the number or structure of chromosomes is associated with adverse obstetric outcome in the form of infertility or recurrent miscarriages. Most of these aberrations are balanced and hence, the person does not manifest any obvious clinical signs and symptoms. However, because of the formation of abnormal gametes (i.e. the eggs and sperm), these chromosomal aberrations result in infertility and recurrent spontaneous pregnancy losses. In the present study, we studied 2000 couples of Indian ethnicity with reproductive failure. Karyotyping was done on the blood sample of these couples using standard protocols. Chromosomal aberrations were detected in a total of 110 (2.78%) couples with structural chromosomal aberrations in 88 cases including reciprocal translocations in 56 cases, Robertsonian translocations in 16 cases, inversions in eight cases, deletions in three cases, derivative chromosomes in five cases and numerical chromosome aberrations in 23 cases. Thus, our study emphasizes the importance of cytogenetic work up in both the associated partners with history of reproductive failure which would help in better patient counselling and management.     

Data on Families of Chromosome Translocation Carriers Ascertained Because of Habitual Spontaneous Abortion

Cytogenetic studies were performed on 1,180 individuals--490 couples + 200 females presenting with habitual spontaneous abortion (HSA). These revealed 24 abnormal results (2.03%)--15 were apparently balanced reciprocal translocations and 9 were Robertsonian translocations. Of 97 pregnancies among the translocation carriers, there were 10 living children and 87 pregnancy losses--a loss rate of 89.7%. There were 11 familial translocations. In 10 familial cases with a full family tree, there were 27 spontaneous abortions and 64 livebirths among the 30 adult translocation carrier relatives--a loss rate of 29.6%. This is twice the risk found in the general population but not as high as in the probands, who had 6 times the abortion rate in the general population. Mechanisms are suggested for this difference. The subsequent pregnancy history of 12 index translocation couples showed an apparently improved pregnancy outcome with 13 further fetal losses and 13 living children, over a follow-up time per patient ranging from 1-5.5 years. However, when the pregnancy losses at ascertainment were combined with postascertainment losses, the overall rate of pregnancy loss remained the same.     

Prenatal diagnosis and postnatal follow-up of a child with two de novo unrelated balanced reciprocal translocations

Two unrelated, apparently balanced, reciprocal translocations involving chromosomes 3 and 17, and 10 and 15 were found in cultured amniotic fluid cells from a 41-year-old 10-gravida. Chromosome analysis of peripheral blood lymphocytes of both parents revealed normal karyotypes. Post-partum examination of lymphocyte cultures from the proband confirmed the chromosome rearrangements. The child showed normal development during follow-up examinations up to the age of 4 years.     

Detection of balanced chromosome rearrangements in 445 couples with repeated abortion and cytogenetic prenatal testing in carriers

Cytogenetic studies were performed in 445 couples presenting because of repetitive abortion. The authors detected a balanced translocation in 19 (4.2%) of the couples, pericentric inversions in 8 (1.8%), and polymorphisms in 52 (11.4%). The results were compared with those obtained in a series of 600 consecutive normal liveborns. Significantly higher frequencies for translocations and polymorphisms were present in couples with repetitive abortion. No sex predominance in translocation carriers was observed, and reciprocal translocations were more common (16 of 19) than the robertsonian type (3 of 19). Contrary to other reports, all of the translocations and inversions were detected among couples without previous abnormal offspring. Cytogenetic prenatal testing in 17 pregnancies from a carrier parent showed that none of the fetuses had the unbalanced karyotype, 13 carried the balanced rearrangement, and 4 had a normal karyotype. Although a risk profile can be obtained for these couples, prenatal testing must be offered to avoid anxiety and unjustified pregnancy interruptions.     

Cytogenetic findings in fifty-five couples with recurrent fetal wastage

Balanced chromosomal translocations in parents and Müllerian abnormalities constitute defined causes of reproductive wastage. Fifty-nine couples with histories of recurrent abortion with or without fetal malformations were evaluated with cytogenetic studies and gynecography. In 44 of the couples with pure abortion histories of two or more spontaneous abortions, three (6.8%) balanced carrier parents were identified. In 11 couples with a mixed history of abortion plus fetal malformation, 3 (27.3%) had balanced translocations in one of the parents. The over-all incidence of Müllerian abnormalities in the group of 59 patients was 11.9%.     

X-chromosome hyperploidy in couples with multiple spontaneous abortions

From 1973 to 1983, cytogenetic analyses were performed on blood samples from 144 couples referred because of two or more spontaneous abortions. Any couple with abnormal offspring in addition to the miscarriages was excluded from the study. Two balanced translocations were found in the 288 individuals examined (0.7%). There was a high frequency of phenotypically normal individuals with cells hyperploid for the X chromosome. This may be a manifestation of an impaired genetic control of chromosome disjunction in these patients.     

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.     

染色体异常与自然流产

染色体异常是自然流产的常见原因,包括夫妇染色体异常和胚胎染色体异常。其中夫妇染色体异常涉及结构异常,如相互易位、罗氏易位、倒位等;数目异常,如特纳综合征、克氏综合征等。胚胎染色体异常以非整倍体为主。文章将对染色体异常与自然流产的相关研究进展予以阐述。