E. S. Sachs

The 11q;22q translocation: A collaborative study of 20 new cases and analysis of 110 families

SummaryFollowing a previous collaborative study (Fraccaro et al. 1980), 20 new cases of 11q;22q translocation are described. Twelve families were ascertained through an unbalanced carrier of the translocation and eight cases were ascertained as balanced carriers. A segregation analysis was performed on the 110 families so far published. It was concluded that the 11q;22q translocation is a relatively frequent event, and that all the cases thus far reported might have the same breakpoints at 11q23.3 and 22q11.2. The translocation seems to be independent of environmental factors and it seems to have a low rate of mutation as indicated by the scarcity of de novo cases. The new data confirmed that only one type of unbalanced karyotype (47,XX or XY+der(22)t(11;22)(q23.3;q11.2)) is found among the offspring of the translocation carriers. The minimal overall recurrence risk for an unbalanced translocation was estimated to 2%. There was no difference between the recurrence risks for male and female balanced carriers, while the trend was confirmed of an excess of female balanced carriers among the phenotypically normal offspring of the t(11;22) female carriers.

Fetal echocardiography: a review of six years experience

Between January 1982 and January 1988, 2,060 pregnant patients were scanned for congenital heart defects (CHD). In 76.5% of these patients, there was an increased risk of CHDs in their offspring. In this group there were 27 CHDs, 17 of which were correctly diagnosed prenatally. In the remaining 23.5% of the patients, the indication for cardiac studies was fetal pathology in the present pregnancy (fetal cardiac arrhythmia, polyhydramnios, severe intrauterine growth retardation, fetal ascites and suspected structural anomalies). In this group there were 82 CHDs, 79 of which were correctly diagnosed prenatally. The incidence of abnormal karyotype was 35%. When a CHD is diagnosed, a realistic prognosis can be given and appropriate obstetric measures taken according to the degree of disease. In cases with a good prognosis careful follow-up may be offered resulting in the delivery of an infant in optimal condition. Reassurance can be given to patients when abnormalities are excluded.

Results of 180 First Trimester Direct Chromosome Studies in Chorionic Villi

First trimester fetal chromosome analysis has been successfully carried out for 180 patients in our center. Cytogenetic studies of chorionic villi have been greatly facilitated by the observation of Brambati and Simoni (1983) that direct preparations after sampling are possible. This method is a great improvement for parents at high risk of producing offspring with anomalies, such as carriers of a translocation or an X-linked disease. Termination of pregnancy in the case of an abnormal fetal karyotype is now possible at 9 weeks instead of at 19 weeks of gestation, after the cultivation of amniotic fluid cells. We report here the results of 180 pregnancies at risk for a chromosomal anomaly or an X-linked disease, with special emphasis on unbalanced fetal translocations, the demonstration of a fragile X chromosome in villi and DNA linkage studies of a male fetus at risk for Duchenne’s muscular dystrophy.

Reproductive behaviour following spontaneous loss of a pregnancy after prenatal diagnosis

One hundred and fifty‐eight women of advanced maternal age with complete follow up who experienced spontaneous fetal loss after prenatal diagnosis were studied for reproductive behaviour as well as prenatal diagnosis in a subsequent pregnancy. A higher rate of subsequent pregnancies amongst women who experienced an early spontaneous abortion after chorionic villus sampling (CVS) was expected compared with women who lost a pregnancy later during pregnancy after amniocentesis. Of the 92 women who underwent CVS in a previous pregnancy, 57 (62%) became pregnant again. Of the 66 women who underwent amniocentesis in the pregnancy that ended in fetal loss, 34 women (52%) had a subsequent pregnancy. The cumulative incidence of subsequent pregnancies was significantly influenced by maternal age but not by parity or the method of prenatal testing. Most women who decided on a new pregnancy opted for prenatal diagnosis. There was a preference for amniocentesis if the patient had previously undergone CVS. However, the reverse was not the case.

An unexpected high frequency of trisomic fetuses in 229 pregnancies monitored for advanced maternal age

SummaryIn 229 pregnancies monitored because of advanced maternal age, 16 (7%) abnormal fetal karyotypes were detected. We found 13 cases of trisomy 21, twice a trisomy 18, and once an additional marker chromosome. The frequency of abnormal fetal karyotypes in different maternal age groups was found to increase from 1:20 at 38–40 years, to 1:16 at 41–43 years, and finally to 1:45 in women of 44–46 years. The overall incidence of chromosomal aberrations and specifically of trisomy 21 is considerably higher than that described in retrospective studies.

Selective Birth in a Dyzygotic Twin Pregnancy with Discordancy for Down’s Syndrome

The discovery of a twin pregnancy by ultrasound at the intake procedure for chorionic villus sampling or amniocentesis is not unusual because of the raised incidence of dizygotic twins at increased maternal age. Since the conception of dizygotic twins is genetically a separate and unrelated event, the risk of abnormalities in each twin is independent, but additive. In advanced maternal age, the risk of chromosomal aneuploidy in one of both fetuses varies between 2 and 6% [1]. This case report discusses the early prenatal diagnosis of twins discordant for Downs syndrome.