Chromosome anomalies as a cause of spontaneous abortion

Reproductive outcome of couples with recurrent miscarriage and balanced chromosomal abnormalities

AIM

Despite known association of parental carriers of structural chromosomal rearrangements with a history of recurrent pregnancy loss (RPL), the possibility of having a miscarriage due to an unbalanced chromosomal aberration remains unknown. There has been limited research on the reproductive outcome of such couples. The present study was done to report the distribution of structural chromosome rearrangements in patients experiencing RPL and to describe subsequent pregnancy outcomes in the carriers.

MATERIAL AND METHODS

Chromosomal analysis was performed on blood samples from 788 individuals with RPL and distribution of chromosomal anomalies was studied. In couples found to have chromosomal rearrangements, pregnancy outcomes were recorded over 2 years. In the subsequent pregnancy, cytogenetic analysis was done on amniotic fluid (obtained at 16-20 weeks), or on miscarriage specimens (in pregnancies that failed to continue).

RESULTS

Chromosomal rearrangements were identified in 6.8% (54/788) cases (including 5.9% reciprocal translocations, 0.7% Robertsonian translocations, and 0.1% inversions). The risk of having a chromosomal aberration was not related to the number of previous miscarriages. Over the next 2 years, two-thirds of the 49 documented pregnancies resulted in a normal live birth, and one-third miscarried. Most miscarriages (56.2%) were euploid, two were trisomic and 12.5% had an unbalanced translocation.

CONCLUSION

 In couples with no other cause of RPL other than a structural chromosomal rearrangement, nearly two-thirds are likely to have a normal outcome in subsequent pregnancy. Couples with pure abortion histories carry higher risk for cytogenetic abnormality than couples with normal children in addition to abortions.

Chromosome variation in the embryos of domestic animals

Chromosome abnormalities in the embryos of domestic animals are mostly eliminated during development. De novo chromosome abnormalities in the embryos of domestic animals have been detected in a larger proportion of embryos produced by in vitro fertilization and somatic cell nuclear transfer than in those produced by natural mating or artificial insemination. The increased incidence of abnormalities in embryos produced in vitro provides evidence for an influence of the embryo production procedures on chromosome stability. Research strategies involving cytogenetics, molecular biology and reproductive biotechnologies hold the promise of yielding insight into the mechanisms underlying chromosome instability in embryos and the impact of the in vitro environment on the chromosome make-up of embryos.

Long-term follow-up of a 26-year-old male with duplication of 16p: Clinical report and review

We report on a 26-year-old male with profound psychomotor retardation and a pattern of dysmorphic features and malformations characteristic for duplication of the short arm of chromosome 16. He has an elongated face, sparse hair, upslanting palpebral fissures, anteverted nostrils, hypoplastic thumbs on both hands, and dislocation of several joints. His chromosome aberration was diagnosed at birth and was due to an unbalanced segregation of a maternal translocation t(2;16)(q36;p11). At 26 years of age he is, to the best of our knowledge, the oldest patient with duplication of 16p reported to date. We present a long-term observation of growth, psychomotor development, dysmorphic features and evolution of his skeletal and joint defects as well as a review of the literature.

[Human cytogenetics. From 1956 to 2006]

The correct enumeration of human chromosomes, only established in 1956, has marked the starting point of the modern cytogenetics. The introduction of banding techniques, then of in situ hybridization techniques, and now of genomic microarray technology allowed a dramatic development of cytogenetics of which the main applications to basic and medical research are evoked in this review.

Double trisomy in spontaneous miscarriages: cytogenetic and molecular approach

BACKGROUND

Although single trisomy is the most common chromosomal abnormality observed within first trimester spontaneous abortions (SA) (>50%), double trisomy (DT) ranges from 0.21 to 2.8% in the literature. Since little is known about mechanisms underlying DT, we report the results of our experience with 517 SA, establishing parental origin and cell stage of non-disjunction when possible in DT cases, and making a revision of those previously reported.

METHODS

Cytogenetic analysis was performed in all aborted specimens. Quantitative fluorescent PCR (QF-PCR) and multiplex ligation-dependent probe amplification (MLPA) were performed in DT cases in order to assess parental origin and stage of error of aneuploidy in addition to its reliability in detecting aneuploidies.

RESULTS

Karyotyping was successful in 321 miscarriages; the rate of DT was 2.18%. Among the seven DT cases reported, three new combinations were found. Maternal origin was established for all DT SA analysed. Meiotic stage of error was presumed meiosis I (MI) for 48,XX+15+22 and 48,XX+8+21, meiosis II (MII) for 48,XXX+18, and MII and MI respectively for 48,XY+18+22. Molecular results agreed with cytogenetic results.

CONCLUSIONS

Similar maternal age-related mechanisms could be implicated in both single and double trisomy. Molecular techniques could be useful in diagnosing not only single but multiple aneuploidy and determining its origin. This will improve our knowledge about mechanisms underlying human aneuploidy, and enable appropriate genetic counselling.

Pathophysiology of histological changes in early pregnancy loss

An early pregnancy loss (EPL) or first-trimester miscarriage is the most common complication of human reproduction, with an incidence ranging between 50 and 70% of all conceptions. Two-thirds of EPL cases present with a thinner and fragmented trophoblastic shell, and reduced cytotrophoblast invasion of the tips of the spiral arteries. This leads to incomplete plugging during early pregnancy, and premature onset of the maternal circulation throughout the placenta. The excessive entry of maternal blood into the intervillous space has a direct mechanical effect on the villous tissue, and an indirect oxidative stress effect that contributes to cellular dysfunction and/or damage. Correlation of in vivo and in vitro data suggests that overwhelming oxidative stress of the placental tissues represents a common pathophysiological mechanism for the different etiologies of EPL. Autosomal trisomies are the most frequent karyotypic abnormalities found in EPL, but the comparison of data from different cytogenetic studies is difficult because of the lack of clinical information in many cases on maternal age, gestational age, time of fetal demise and the cytogenetic methodology employed. The majority of authors did find a weak association between villous morphologic features and chromosomal abnormalities, with the exception of partial mole triploidy. The comparison of ultrasound findings and placental histological data indicates that villous changes following fetal demise in utero could explain the overall low predictive value of placental histology alone in identifying an aneuploidy or another non-chromosomal etiology. By contrast, the histological features of complete and partial hydatidiform molar EPL are so distinctive that most cases of molar EPL are correctly diagnosed by histological examination alone. Overall, histopathology when correlated with in vivo ultrasound/Doppler has provided novel clues to the pathophysiology of EPL. Prospective studies are needed to evaluate the impact of these findings on routine histopathologic examination in first-trimester miscarriages.

The contribution of placental oxidative stress to early pregnancy failure

In cases of miscarriage, onset of the maternal blood flow to the placenta is precocious and disorganized compared with this event in normal pregnancy. We sought to determine whether this difference is associated with excessive levels of oxidative damage and stress in the placental tissues. Morphological and immunohistochemical markers of cellular stress and damage, including expression of heat shock protein 70, formation of N-Tyr residues, and lipid peroxidation, were increased in tissues obtained from missed miscarriages compared with controls. The effect was greatest in those pregnancies of shorter than 77 days' duration and with evidence of recent fetal demise. It was associated with increased apoptosis and decreased numbers of mitotic cells, indicating that oxidative stress overwhelms cellular antioxidant defense systems. No differences were observed between miscarriages with normal and abnormal karyotypes. The spectrum of villous changes occurring after fetal demise indicates that the duration of placental retention in utero after fetal demise is a critical determinant of villous histology. The causes of many miscarriages remain unclear; however, our findings indicate that placental oxidative stress with resultant damage to the syncytiotrophoblast, secondary to early onset of the maternal circulation, may provide a final common mechanism.

Duplication of chromosome region (16)(p11.2 --> p12.1) in a mother and daughter with mild mental retardation

We report a 40-year-old female with mild mental retardation and behavior problems and her 6-year-old daughter. Chromosome analysis showed that both patients had a proximal duplication in the short arm of chromosome 16. The aberration was characterized further with band-specific probes, resulting in a 46,XX,dir dup(16)(pter --> p11.2::p12.1 --> qter) karyotype. The clinical and cytogenetical findings are compared to other patients with partial trisomy 16p reported in the literature.

Chromosomally abnormal early ongoing pregnancies: correlation of ultrasound and placental histological findings

The pathophysiology of placental microscopic changes in chromosomally abnormal pregnancies remains poorly understood. We have reviewed the relationship between ultrasound findings and villous histological features in a group of 25 ongoing pregnancies presenting with fetal aneuploidy at 11 to 15 weeks of gestation. The chromosomal abnormalities were diagnosed by chorion villous sampling, and the data were compared with those of a group of 25 chromosomally normal pregnancies undergoing surgical termination and matched for gestational age. The aneuploid group included 10 pregnancies with trisomy 21, nine with trisomy 18, three with triploidy, two with monosomy X, and one with trisomy 13. The overall degree of agreement between the two investigators for the histological diagnosis was good (kappa, 0.64), and the sensitivity of histology ranged between 72.0% and 80.0%. Fetal and placental edema was observed on scan in 10 and 7 cases, respectively, of the aneuploid group and was systematically associated with trophoblastic hypoplasia, stromal edema, or cavitation, reduced vascularization, and ramification of the main villous trunks. Fetoplacental hydrops was not observed in the euploid group. These findings indicate that histological changes observed in the placenta of fetuses from ongoing pregnancies presenting with aneuploidy can be linked with early fetal hydrops. The villous features in these cases are probably secondary to a reduction in the villous circulation due to a cardiovascular defect and leading to generalized stromal edema. The reduced villous branching and trophoblastic hypoplasia could be secondary to the enlargement of all villous types or to a basic defect in placental development.

Trisomy 16 fetus surviving into the second trimester

A 27-year-old gravida 4, para 3 was found to have anhydramnios at 14 weeks' gestation following a size/date discrepancy noted at her routine prenatal visit. A detailed ultrasound revealed multiple fetal anomalies including congenital heart defect, chest hypoplasia, and bilateral dysplastic kidneys. Karyotype revealed trisomy 16 in 15/15 cells from a tissue specimen obtained from the fetal cord insertion site following elective pregnancy termination.

Turner syndrome and occlusion of the internal carotid artery

A 2-year-old girl with Turner syndrome was admitted with left hemiplegia and left facial palsy. Serial cranial computed tomographic scan demonstrated multiple cerebral infarctions in the right putamen and right medial cortical areas. Single photon emission computed tomographic scan revealed hypoperfusion from the right frontal to the right temporal area. Right carotid angiography showed narrowing and occlusion of the right internal carotid artery at the sphenoidal portion. Collateral circulation was not detected between the external and internal carotid arteries. Left carotid angiography revealed that the left anterior artery was narrow, and that the left internal carotid artery provided blood to the right internal carotid artery through the anterior communicating artery. These findings suggested that the cerebrovascular abnormality might be due to congenital hypoplasia of arteries in this patient. The unusual combination of cerebral infarction and Turner syndrome was reported.

Variable clinical expression of mosaic trisomy 16 in the newborn infant

Trisomy 16 is common in embryos and fetuses aborted early during development. Mosaicism for trisomy 16 is sometimes encountered during prenatal diagnosis, particularly with chorionic villi biopsy specimens, and, until recently, was thought to be confined to the placenta. However, recently, several liveborn infants with trisomy 16 mosaicism have been described. We report on an additional liveborn infant with trisomy 16 mosaicism and compare the clinical findings with those of the previously reported cases in an attempt to delineate a mosaic trisomy 16 syndrome. Cytogenetic analysis from our patient showed that there was a different proportion of abnormal cells in different tissues and that the anomaly was undetectable in blood lymphocyte cultures. This observation was consistent with some of the previous reports. DNA analysis of parents and child was carried out using a polymorphic dinucleotide marker that maps to the long arm of chromosome 16. This analysis showed that the extra chromosome 16 in the infant was maternal in origin and suggested that the nondisjunction was probably a first meiotic division error. Our results suggest that an investigation of multiple tissues is required before concluding that mosaicism is confined to the placenta. We conclude that a finding of trisomy 16 mosaicism at prenatal diagnosis should be regarded with extreme caution. This diagnosis may be associated with a highly variable phenotype that may occasionally be compatible with extrauterine life.

Trisomy 4 in a fetus with cyclopia and other anomalies

We report on an 18-week fetus with cyclopia, alobar holoprosencephaly, complex congenital heart defect, anal atresia, oligosyndactyly, cystic hygroma, and skeletal abnormalities with trisomy 4. Structural anomalies were detected on routine ultrasound of the pregnancy of a 17-year-old G3 P1 TAB1 woman with sickle cell trait. Trisomy 4 conceptuses usually miscarry in the first trimester. We are aware of no other reports of a fetus with trisomy 4 and cyclopia. Causal association of chromosome abnormalities and holoprosencephaly sequence may be more apparent in embryos and early fetuses than term fetuses because of poor viability of affected conceptuses.

Trisomy 16p in a liveborn infant and review of trisomy 16p

We report on an infant boy with duplication of part of 16p and partial deficiency of 9p: 46,XY, -9, + der(9)t(9;16)(p24;p13.1)mat. The child has the typical phenotype of dup(16p) even though the extra piece of 16p is small (16p13.1----pter). Manifestations include severe developmental delay, rounded face, sparse hair, ear anomalies, hypertelorism, cleft soft palate, a thin vermilion border of the upper lip, and left renal dysgenesis. We review 16p duplications.

Ullrich-Turner syndrome with agenesis of the corpus callosum

We report on a 19-year-old woman with 45,X Ullrich-Turner syndrome who was severely mentally retarded and had hypotonia. Computer tomography (CT) scan showed agenesis of the corpus callosum. There have been few reports of gross developmental central nervous system (CNS) abnormalities in Ullrich-Turner syndrome. Only one case of Ullrich-Turner syndrome with agenesis of the corpus callosum has been reported. The high prenatal lethality of Ullrich-Turner syndrome may mask a CNS abnormality.

Fertility after contraception or abortion

There is a very small correlation, if any, between the prior use of OCs and congenital malformations, including Down's syndrome. There are few, if any, recent reports on masculinization of a female fetus born to a mother who took an OC containing 1 mg of a progestogen during early pregnancy. However, patients suspected of being pregnant and who are desirous of continuing that pregnancy should not continue to take OCs, nor should progestogen withdrawal pregnancy tests be used. Concern still exists regarding the occurrence of congenital abnormalities in babies born to such women. The incidence of postoperative infection after first trimester therapeutic abortion in this country is low. However, increasing numbers of women are undergoing repeated pregnancy terminations, and their risk for subsequent pelvic infections may be multiplied with each succeeding abortion. The incidence of prematurity due to cervical incompetence or surgical infertility after first trimester pregnancy terminations is not increased significantly. Asherman's syndrome may occur after septic therapeutic abortion. The pregnancy rate after treatment of this syndrome is low. The return of menses and the achievement of a pregnancy may be slightly delayed after OCs are discontinued, but the fertility rate is within the normal range by 1 year. The incidence of postpill amenorrhea of greater than 6 months' duration is probably less than 1%. The occurrence of the syndrome does not seem to be related to length of use or type of pill. Patients with prior normal menses as well as those with menstrual abnormalities before use of OCs may develop this syndrome. Patients with normal estrogen and gonadotropin levels usually respond with return of menses and ovulation when treated with clomiphene. The rate for achievement of pregnancy is much lower than that for patients with spontaneous return of menses. The criteria for defining PID or for categorizing its severity are diverse. The incidence of PID is higher among IUD users than among patients taking OCs or using a barrier method. The excess risk of PID among IUD users, with the exception of the first few months after insertion, is related to sexually transmitted diseases and not the IUD. Women with no risk factors for sexually transmitted diseases have little increased risk of PID or infertility associated with IUD use. There appears to be no increased risk of congenital anomalies, altered sex ratio, or early pregnancy loss among spermicide users. All present methods of contraception entail some risk to the patient. The risk of imparied future fertility with the use of any method appears to be low.(ABSTRACT TRUNCATED AT 400 WORDS)

Congenital heart disease among spontaneous abortuses and stillborn fetuses: prevalence and associations

The prevalence, range, and associations of congenital heart disease (CHD) were studied among 400 spontaneous abortuses between 9 and 40 weeks' gestation. Fifty-two (13.0%) cases of CHD were detected. To minimize selection bias the specimens were grouped by external appearance and the prevalence expressed accordingly. CHD was detected in 21 (7.3%) of 289 externally normal and 31 (27.9%) of 111 externally abnormal fetuses. Ventricular septal defect (VSD) was the most frequent CHD found in isolation as well as in combination with extracardiac malformations. Seventy-five percent of isolated CHD was VSD. Forty (69.2%) of the 52 cases of CHD were associated with extracardiac malformations. Chromosomal syndromes were responsible for a minimum of 19.2% of the cases and suspected in up to 36.5%. The most frequent associations involved the musculoskeletal system, central nervous system, abdominal wall, and kidneys. In contrast, studies of liveborn infants have reported 70% of CHD as isolated defects, including many CHD infrequently seen among spontaneous abortuses. This suggests that fetuses with isolated CHD often survive to term, and CHD does not significantly affect the survival of the fetus in utero. Ventricular septum formation may be particularly susceptible to hemodynamic changes and may be indicative of an underlying pathologic condition that also leads to a spontaneous abortion.

Familial transmission of 16p trisomy in an infant

Based on four reported cases including the present case, 16p trisomic infants have remarkably similar features. These are severe developmental delay, psychomotor retardation, typical facies, and anomalies of extremities.

Cytogenetic abnormalities among spontaneously aborted previable fetuses

We have reviewed spontaneously aborted fetuses of 9 to 20 developmental weeks. All fetuses with either external or internal developmental defects and those with maternal history of repeated spontaneous abortion were studied cytogenetically. Among 723 fetuses the cytogenetically proven prevalence of chromosome abnormalities was 5.8%. Inclusion of suspected chromosome abnormality based on morphologic findings resulted in an overall prevalence of only 7.1%. This prevalence and restricted spectrum of chromosome abnormalities, which included monosomy X, triploidy, gonosomal aneuploidy, trisomies 13, 18, and 21, resembled the prevalence and spectrum found among perinatal deaths and differed both in prevalence and type from those chromosome abnormalities found in spontaneous abortions occurring during the embryonic period. Monosomy X was the most common chromosome abnormality among previable fetuses. Both monosomy X and triploidy were more frequently detected in the early fetal period than in perinatal deaths. The combined prevalence of autosomal trisomies was equal to that which has been reported in the perinatal deaths. Chromosomal structural abnormalities, seen in perinatal deaths, were not found in our study.

Recurrent pregnancy losses and parental chromosome abnormalities: a review

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.

A gradual fixation method for chromosomal preparations of human oocytes

Eleven oocytes were recovered after follicle aspiration carried out in nine women during laparoscopy or laparotomy. All oocytes were classified as preovulatory, judged by the fully dissociated cumulus. After elimination of the cumulus, ten of the oocytes exhibited the first polar body, and one was degenerated. A gradual fixation method was used for the chromosomal preparation of the oocytes. The quality of the preparations was improved, compared with the previously used air-drying technique. Nine of ten preparations from oocytes with first polar body displayed chromosomes. These sets consisted of well-spread meiotic chromosomes, and in six of them the chromosome complements of the first polar body could be seen, although quite distinct from the oocyte complement. Of eight preparations where the chromosomes could be counted, six showed 23 chromosomes, and two were abnormal, showing 21 and 16 chromosomes.

Deletion mapping of the T/t complex: evidence for a second region of critical embryonic genes

The developmental effects of three different deletion mutations of the T/t complex of the mouse have been studied. The three mutations, TOak Ridge (OR), TOrleans (TOrl), and THair pin (THp), each produce a unique homozygous lethal phenotype: THp homozygotes fail to develop normally past the morula stage, TOrl homozygotes past the blastocyst stage, and TOR homozygotes past the egg cylinder stage. In compound embryos (TX/TY), the lethal phenotype observed corresponds to the shared length of deleted chromosome. This interaction allows the regions of chromosome 17, containing genetic information critical to early mammalian development, to be mapped.

Duplication of 16p from insertion of 16p into 16q with subsequent duplication due to crossing over within the inserted segment

Two members of a large family had a similar multiple congenital anomalies mental retardation (MCA/MR) syndrome and an identical aberration of chromosome 16. Their mothers, who are first cousins, had a different abnormality of one chromosome 16, which appeared to be an acrocentric. We interpret these findings as an insertion of a segment of 16p into 16q. following a three-break rearrangement and meiotic crossing over. The two abnormal children have a duplication of 16p11 leads to p13. The clinical manifestations of these patients differ from those of previously reported cases of dup(16p).

Comparison of somatic and germ cell models for cytogenetic screening

A variety of in vivo mammalian test models are available for screening of chemicals for mutagenicity at the chromosomal level. These models have been grouped into those focusing on somatic cell effects and those dealing with germ cell effects. An analysis of available literature indicates that 76 compounds have been tested from chromosome effects in both somatic and germ cells. Of these, concordant results (positive-positive or negative-negative) were obtained with 58 compounds. Of the remaining 18 compounds with discordant results, all were positive in somatic cells, but negative in germ cell assays. These results suggest an inherent relative insensitivity of germ cells themselves to mutagenic chemicals. In the context of screening for safety evaluation purposes, this analysis suggests that a negative somatic-cell response can be taken as highly predictive of negative results in a germ cell assessment.

Tetraploid conceptus with three paternal contributions

Cytogenetic and biochemical polymorphisms have been used to determine the origin of a tetraploid conceptus. Genetic polymorphisms were found in chromosomes 1, 6, 9, 15, 16, 22 and the sex chromosomes. The conceptus was found to have one maternal and three paternal contributions, indicating an origin other than a failure of cytokinesis at the first cleavage division of the zygote. The results presented are in favour of a trispermic origin of the conceptus.

Serial beta-subunit human chorionic gonadotropin doubling time as a prognosticator of pregnancy outcome in an infertile population

Prospective evaluation through the use of radioimmunoassay of the beta-subunit of human chorionic gonadotropin (beta-hCG) in blood samples obtained during the first 30 days of gestation was performed on an infertile population at high risk for pregnancy loss. Four hundred and fourteen samples in 281 pregnancies were analyzed. On the basis of single, random beta-hCG samples in asymptomatic patients, 77% of successful pregnancies and 59% of abortions were correctly identified. On the basis of beta-hCG doubling time (mean 2.2 days +/- 1.0 [2 SD]) computed from serial sampling, again in asymptomatic patients, 88% of successful pregnancies and 76% of abortions were correctly identified. beta-hCG doubling time appears to provide a reliable method of evaluating early pregnancy prognosis with significantly greater ability to identify problem pregnancies within the first 30 days of gestation than does single random hCG values.

Association of ribosomal genes in the fibrillar center of the nucleolus: a factor influencing translocation and nondisjunction in the human meiotic oocyte

Prophase I meiosis was studied in the human oocyte obtained from 16- to 24-week-old fetuses. Electron microscopy and silver stainihg showed that, at pachytene, the ribosomal genes belonging to several chromosomes are gathered in the same nucleolar fibrillar center, where they are embedded in an argyrophilic protein. The nucleolus showed spontaneous segregation of its components due to temporary inactivation of the ribosomal genes. The fibrillar center, separated from the other nucleolar components, was penetrated as midpachytene by chromatin fibers containing rDNA emanating from one to three nucleolar bivalents. Thus, the ribosomal genes from 4-12 chromatids are temporarily juxtaposed inside the same structure. Such a structural arrangement is completely different from that observed in the pachytene-stage mouse oocyte, where two independent and active nucleoli, each displaying its own fibrillar center, were formed on the bivalents containing paired ribosomal genes. These different structural patterns are correlated with the high frequency of nondisjunction in the human oocyte and the relative infrequency of such in the mouse oocyte. The pattern observed in the human oocyte may be a cause of translocations.

Parents' evaluations of genetic counselling

Genetic counseling represents a new and important health service, but little is known about how the clients of genetic clinics actually experience and view the genetic counseling process. This paper reports on the evaluations made by clients of a genetics clinic and their recommendations for ways to improve and expand this service. In their comments, clients stressed the need for more time and individual attention from genetic counsellors, additional follow-up and supportive counselling, and increased efforts to educate the general public about birth defects. Their recommendations are discussed in terms of the implications for developing and improving genetic counselling services.

A rapid and simple sandwich-method used for chromosome analysis from small fetal and adult biopsy specimens

A new Sandwich-Method is described which uses aborted material and yields a high frequency of metaphases. Chromosome studies may be performed after 7--8 days without subculturing. It is possible to freeze the original tissue for later cell culture.

Studies in mice on the mutagenicity of two contraceptive drugs

An experiment is described which tests for visible and invisible mutants in mice treated with four different doses each of the contraceptives Gynanovlar and Lyndiol. The results show that there is no reason to suppose that either substance has an appreciable mutagenic effect, expressed as an increase of antenatal and postnatal lethals or visibles. The substrain CBA/CagCam, used throughout, has an incidence of 0.27% of singly occurring abnormalities, mainly of the appendicular skeleton, which distinguishes it from the parent CBA strain and its axial variation described by Gruneberg (1963).

Cytogenetic and histologic analyses of spontaneous abortions

In a study of spontaneous abortions the correlations between karyotype (166 cases), anamnestic data, and macroscopic and histologic findings in placentas (107 cases) and embryos (73 cases) were analyzed. The main results were: 1. The rate of chromosomal aberrations was 39%. Trisomies predominated (60%), followed by monosomy X (20%), triploidies (14%), and structural aberrations (6%). 2. In trisomies a clear prevalence of female sex constitution (2:1) was observed. In normal karyotypes a slight prevalence of females was seen (1.2:1). 3. With increasing maternal age, more trisomies were found in the abortions. 4. Women whose index abortion had a normal karyotype had a history of fewer births but more abortions. 5. Trisomies of acrocentric chromosomes were mainly chorionic sacs with an embryo, while trisomies of the other autosomes resulted in intact empty sacs. 6. The average developmental stage of the embryos was 5 weeks, with a mean gestational age of 14 weeks. Gross malformations were found in 58% of the embryos.

Trisomy 16p in a liveborn infant and a review of partial and full trisomy 16

An abnormal female infant, who survived for 10 months with almost complete trisomy 16p and monosomy of sub-band 21q22.3, is described. The chromosome anomaly was the result of an unbalanced segregation of a maternal balanced translocation t(16;21)(p11;q22.3). The partial monosomy was considered to have had little or no adverse phenotypic effect. Cases with trisomy of chromosome 16 material are reviewed. It appears that while full trisomy 16 always results in early spontaneous abortion, trisomy 16p or 16q may be compatible with limited postnatal survival.

Multinationals and health: reflections on the Seveso catastrophe

On July 10, 1976, a cloud of vaporized products containing dioxin escaped from a deposit of a plant of the Icmesa firm in the northern suburbs of Milan. The fallout was deposited on a vast zone in the municipalities of Desio, Seveso, Meda, and Cesano. Dioxin was not the desired product of the industrial process, but rather an impurity which generally accompanies trichlorophenol, and, to a smaller extent, the products synthesized from trichlorophenol. Among these there are hexachlorophene and the herbicide 2,4,5-trichlorophenoxyacetic acid, which was used as a defoliant in the Vietnam War. After describing toxicological properties of dioxin, this paper examines the role of multinational corporations and of capitalist governments in exploiting not only the people of underdeveloped lands, but also workers of developed countries, transforming into capital not only the increased value of man, but also the conditions, harmfulness, and risks of work.

Cytophotometric DNA-measurements in abortion

Triploid abortuses ascertained by cytogenetic analysis histologically show molar degeneration of the placental villi. Changes of this type which are occasionally encountered in routine material may suggest chromosome abnormality although chromosome analysis is precluded due to fixation. However, suspected triploidy can be proven in Feulgen-stained sections by DNA-measurements. In nine cases of molar degeneration selected according to histological criteria, evaluation of nuclear DNA-content revealed only two triploid placentae. It seems acceptable to assume that such molar changes in diploid abortuses may be due to prolonged retention of the placenta. Thus, histological criteria may suggest but cannot establish the diagnosis of triploidy. In case of susepcted triploidy of the feto-placental tissue, DNA-measurements can confirm or exclude the diagnosis even if a cytogenetical analysis is not applicable.