Antenatal screening for cystic fibrosis: a trial of the couple model.

OBJECTIVE--To assess the delivery and acceptability of antenatal couple screening for cystic fibrosis. Carrier status was notified only when both members of a partnership had cystic fibrosis alleles and therefore a one in four risk of having an affected child. DESIGN--Mouthwash samples were tested when both partners participated. Results were returned only to positive couples. SETTING--Two large maternity hospitals in Edinburgh. SUBJECTS--Screening was offered to all couples who booked at one of the two hospitals. MAIN OUTCOME MEASURES--(a) The take up of screening, carriers and carrier couples identified, take up of prenatal diagnosis, and numbers of affected fetuses detected; (b) questionnaire measures of patient satisfaction and stress. RESULTS--Screening was offered to 8536 couples. 714 (8.4%) were regarded as ineligible, usually because of late booking or absence of a partner. 1900 (24.3%) of the remainder declined screening. Among the 5922 screened couples, four tested positive--that is, both partners were cystic fibrosis heterozygotes. All four elected to have prenatal diagnosis. There were three terminations of pregnancy because of an affected fetus, one couple having two successive pregnancies with affected fetuses. The participation rate was 76% for eligible couples (5922/7822) and 69% for all couples (5922/8536). Only 89 screened couples (1.5%) requested information on individual carrier status. No anxiety was detected among a cohort of the screened population, and 99% of questioned participants expressed satisfaction with the concept of couple screening. CONCLUSIONS--Antenatal couple screening is a satisfactory and acceptable way of screening for cystic fibrosis and has been adopted as routine in the two trial hospitals.     

Requests for prenatal diagnosis from parents of children with cystic fibrosis

The request for prenatal diagnosis of cystic fibrosis has been evaluated by an interview during a visit at a cystic fibrosis clinic among 32 couples whose one or several children are affected. Six couples resorted to the procedure between June 1984 and October 1985. In all the cases, in these families the only child (or children) alive was affected. The diagnosis of the disease in the first affected child reduces the number of children planned by the family. The significant use of the test, since its availability points to the existence of a real demand from the parents.     

The place of prenatal diagnosis in genetic counseling (1982-1983)

34.2% of couples seen during the years 1982 and 1983 for genetic counselling had some kind of familial anamnesis such as affected partner or relative or children. They could have benefit from prenatal diagnosis who would have been accurate informative twice on three times. Indications methods and accuracy are studied in consideration to the reason of referring and the level of the risk. Genetic counselling and prenatal diagnosis appear as preventive means adapted to each consultant. Otherwise systematic ultrasonography allows a true prevention from which 17.6% of the couples having give birth to affected children could have benefit.     

Preimplantation genetic diagnosis and embryo research--human developmental biology in clinical practice.

Research on human preimplantation embryos in vitro is controversial. Yet it has been the cornerstone for the development important clinical assisted conception techniques. Preimplantation genetic diagnosis which has developed out of this assisted reproductive technology for the first time provides a realistic alternative to prenatal diagnosis and abortion for couples who are at substantial risk of conceiving a pregnancy affected by a known genetic disorder. It also provides the first real hope of therapy for couples who have suffered repeated miscarriages due to chromosome translocations. However, the ability to test very early embryos in vitro presents new and unusual ethical challenges for clinicians and developmental biologists.     

Carrier screening for beta-thalassemia during pregnancy in India: a 7-year evaluation

AIM: Premarital screening for beta-thalassemia is not widely acceptable in India; hence, we evaluated the effectiveness of antenatal screening and counseling over 7 years. METHODS: 61,935 pregnant women were screened using the single-tube osmotic fragility test during their first antenatal visit. Individuals who were positive were investigated further for diagnosis of beta-thalassemia and other abnormal hemoglobins. Spouses of carrier women were tested whenever available. Couples at risk were given the option of prenatal diagnosis. RESULTS: Only 19% of the women registered at the antenatal clinic in the first trimester of pregnancy, and 14% of the women were positive per the osmotic fragility test; 1020 beta-thalassemia heterozygotes and 213 women with other hemoglobinopathies were identified, majority being in the second and third trimesters. Seven hundred and thirteen (69%) of their husbands could be tested, and 37 couples at risk were identified. Only 15 couples had a prenatal diagnosis done. Four couples with affected fetuses opted for termination of pregnancy. The remaining couples either did not respond after counseling or the pregnancies were advanced for prenatal intervention. CONCLUSION: This first large study shows that antenatal screening is acceptable in India; however, awareness generation is still a primary requisite to make women register early at antenatal clinics and bring their spouses for screening when required.     

Active cascade testing for carriers of cystic fibrosis gene.

OBJECTIVE--To examine the acceptability, practicability, efficiency, and application of active screening for carriers of the cystic fibrosis gene in the extended families of those in whom the disease is present (Cascade screening). DESIGN--Paediatricians and physicians provide details of their affected patients, pedigrees are drawn up, and relatives offered tests after initial contact by the affected nuclear families. Affected patients are genotyped in a laboratory with a special interest in the genetics of cystic fibrosis. SETTING--North Western health region. SUBJECTS--Relatives and partners of 607 people with cystic fibrosis. INTERVENTIONS--Genetic counselling by letter for people found to be carriers; formal genetic counselling and when indicated arrangements for prenatal diagnosis for couples discovered to be carriers. MAIN OUTCOME MEASURES--Number of carrier couples detected; action in pregnancy of detected carrier couples; extent of the uptake of screening by relatives. RESULTS--Of 1563 relatives or partners tested, 15 carrier couples were detected; of nine pregnancies undertaken by these 15, eight had prenatal tests and three terminated pregnancies. An average of 16 people per family have come forward for testing so far. CONCLUSIONS--Cascade screening for carriers of cystic fibrosis is well accepted by relatives, especially on the mother''s side of the family; it is 10 times more efficient in detecting carrier couples than unfocused screening. Detected carrier couples make practical use of the information in pregnancy. Active cascade screening for carriers is effective in cystic fibrosis and widespread application is recommended. These principles could be applied to other recessive disorders.     

Prevention of homozygous beta-thalassemia by carrier screening and prenatal diagnosis in Sardinia.

We report here results of a 3-year pilot voluntary screening program coupled with prenatal diagnosis directed to the prospective prevention of homozygous beta-thalassemia (beta-thal) in Sardinia. The screening program took two approaches: outreach community testing and hospital testing on request after a period of sensibilization. The outreach testing was very effective as, taking into account the already known number of couples at risk with an affected proband (20), 74% of the couple at risk expected (61) on the basis of the carrier rate were identified. Less effective was the hospital testing in which half of the couples at risk expected were detected (502 with the 199 without an affected proband). After nondirective genetic counseling, approximately 85% of the couples at risk, which had a pregnancy, with no statistically significant difference between those with and those without a proband, requested prenatal testing. This figure showed a steadily increase from the beginning in 1977 to 1980. All the pregnancies (42), but two carrying homozygous fetuses, were terminated on parental request. A continuous hospital survey of thal-major admissions in the different hospitals of the counties showed a steady decline in the incidence figure at birth from 1976 (1:213) to 1978 (1:290). These results showed that even in a medium-developed, rural, Catholic population screening coupled with prenatal diagnosis can be successful in the control of a fatal, recessively inherited disorder.     

Human embryonic stem cells carrying mutations for severe genetic disorders

Human embryonic stem cells (HESCs) carrying specific mutations potentially provide a valuable tool for studying genetic disorders in humans. One preferable approach for obtaining these cell lines is by deriving them from affected preimplantation genetically diagnosed embryos. These unique cells are especially important for modeling human genetic disorders for which there are no adequate research models. They can be further used to gain new insights into developmentally regulated events that occur during human embryo development and that are responsible for the manifestation of genetically inherited disorders. They also have great value for the exploration of new therapeutic protocols, including gene-therapy-based treatments and disease-oriented drug screening and discovery. Here, we report the establishment of 15 different mutant human embryonic stem cell lines derived from genetically affected embryos, all donated by couples undergoing preimplantation genetic diagnosis in our in vitro fertilization unit. For further information regarding access to HESC lines from our repository, for research purposes, please email dalitb@tasmc.health.gov.il.     

Social Effects of Genetic Counselling

In a follow-up study of 104 subjects referred for genetic counselling between 1965 and 1969 all were at risk of having children with a variety of serious genetic disorders. Most subjects were in social classes III and IV, were married, in their late 20s, and already had an affected child. Sixty-three per cent. were referred by hospital consultants, 27% by their general practitioners, and 10% were self-referrals. All of those counselled appeared to have appreciated the genetic implications, although four overestimated the risks and 11 underestimated the risks.Of those at high risk (greater than 1 in 10) of having an affected child 10 out of 55 couples “planned” further pregnancies despite the risks. In two this was because they had been unable to adopt a child, in four because they had no living children and the disorders in question usually resulted in stillbirth or death in infancy so that the “burden” of an affected child would be of relatively short duration, and one mother had had antenatal diagnosis and selective abortion. Most of the couples in the low-risk group (less than 1 in 20) were reassured and planned further pregnancies.     

Reproductive patterns and thalassaemia major

This study investigated the effect of the diagnosis of transfusion-dependent homozygous beta-thalassemia on subsequent parental reproductive patterns in 44 families in New South Wales. The results indicate a shift over time from parental risk-taking (either consciously or in ignorance of the implications of the diagnosis) to premature curtailment of reproduction to the likelihood of attaining birth expectations through antenatal diagnosis. 67% of families with both of their 1st 2 children affected by thalassemia major had additional children, compared with 38% of those where the 1st child was affected and the 2nd child was unaffected and 37% of families where the 1st child was unaffected and the 2nd child was affected. Overall, 48% of mothers of children with thalassemia major had as many children as they had expected at the time of marriage, 13% had more, and 39% had fewer children. The mothers of older children were less likely to have had the planned number of births than those of children born more recently. The value of antenatal diagnosis to couples at risk of thalassemia appears to have been to enable them to meet or almost meet their birth expectations.     

Attitudes toward the prenatal diagnosis of cystic fibrosis: factors in decision making among affected families.

The objective of this study was to explore psychosocial factors underlying decisions about use of prenatal diagnosis for cystic fibrosis (CF), among parents of affected children. Anonymous survey questionnaires, supplemented by voluntary interviews, were used at 12 CF centers in six New England states, for a consecutive sample of families of minor children visiting CF centers during a 4-mo period. In all, 227 (71%) of 318 families responded. We hypothesized that attitudes toward utilization would be affected by (a) intentions to have children, (b) knowledge, (c) perception of risk, (d) the health of the child with CF, (e) expectations about the child's future, (f) attitudes toward abortion, (g) insurance, (h) genetic counseling, and (i) sociodemographic factors (including attendance at religious services). Of the 227 couples who responded, 69% were surgically sterile, over 45 years of age, widowed, or divorced, and 31% were at risk. Of 70 at-risk couples, 44% intended to have more children; of these, 77% had had or were considering CF prenatal diagnosis. Most families knew CF could be diagnosed prenatally; 20% would terminate for CF. Among intended prenatal diagnosis users, 44% would carry a fetus with CF to term, 28% would abort, and 28% were undecided. Stepwise logistic regression showed three variables significantly related to intentions to use prenatal diagnosis: (1) respondent's willingness to abort for CF (P less than .02, odds ratio 3.36), (2) respondent's siblings' approval of abortion for CF (P less than .03, odds ratio 2.99), and (3) respondent listed no accomplishments for the child with CF (P less than .09, odds ratio 3.01). The majority of affected families reject selective abortion for CF; many will curtail childbearing rather than use prenatal diagnosis.     

Effect of introducing antenatal diagnosis on reproductive behaviour of families at risk for thalassaemia major.

Families who were at risk of producing a child with thalassaemia major were studied to determine the sequential effects on their reproductive behaviour of knowing the risk and, subsequently, of knowing that antenatal diagnosis was available. Knowing the risk caused them virtually to stop reproduction and to seek termination of 70% of pregnancies, most of which were accidental. The introduction of antenatal diagnosis in 1975 permitted the resumption of nearly normal reproduction by at-risk families, with fewer than 30% of pregnancies being terminated for thalassaemia major. All couples at risk for thalassaemia major should be detected and counselled before they produce an affected child; responsibility for either choosing or refusing antenatal diagnosis should be theirs alone.     

Case series of fertility treatment in HIV-discordant couples (male positive, female negative): the Ontario experience

The success of combination antiretroviral therapies for the treatment of human immunodeficiency virus (HIV) has resulted in prolonged life expectancy (over 40 years from diagnosis) and an improved quality of life for people living with HIV. The risk of vertical HIV transmission during pregnancy has been reduced to less than 1%. As a result of these breakthroughs and as many of these individuals are of reproductive age, fertility issues are becoming increasingly important for this population. One population in which conception planning and reduction of horizontal HIV transmission warrants further research is HIV-discordant couples where the male partner is HIV-positive and the female partner is HIV-negative. Sperm washing is a technique carried out in a fertility clinic that separates HIV from the seminal fluid. Although sperm washing followed by intrauterine insemination significantly reduces the risk of horizontal HIV transmission, there has been limited access to the procedure in North America. Furthermore, little is known about the conception decision-making experiences of HIV-discordant couples who might benefit from sperm washing. Chart reviews and semi-structured interviews were completed with 12 HIV-discordant couples in Ontario, Canada. Couples were recruited through HIV clinics and one fertility clinic that offered sperm washing. Participants identified a number of factors that affected their decision-making around pregnancy planning. Access to sperm washing and other fertility services was an issue (cost, travel and few clinics). Participants identified a lack of information on the procedure (availability, safety). Sources of support (social networks, healthcare providers) were unevenly distributed, especially among those who did not disclose their HIV status to friends and family. Finally, the stigmatisation of HIV continues to have a negative affect on HIV-discordant couples and their intentions to conceive. Access to sperm washing and fertility service is significantly limited for this population and is accompanied with a number of challenges.     

Genetic counselling (results of ten years experience). IV. Attitude of persons seeking counselling and reliability of the counsel (author's transl)

The authors, from their personal experience arising from 766 consultations, show that the percentages of marriages or procreations in subjects themselves suffering from a disorder, or with affected relatives, are independent of the risk estimated for their offspring. The procreation rate in couples with affected children is lower in high risk cases and depends also on the family composition. It appears that this procreation is voluntary in the great majority of cases because there were very few terminations of pregnancy among the couples seen before procreation. The estimated risks correspond to the risks observed but the authors insist that there is a relatively high proportion (4.4 per cent) of children born with a disorder different from that which motivated the consultation.     

Clinical applications of MARSALA for preimplantation genetic diagnosis of spinal muscular atrophy

Conventional PCR methods combined with linkage analysis based on short tandem repeats(STRs) or Karyomapping with single nucleotide polymorphism(SNP) arrays, have been applied to preimplantation genetic diagnosis(PGD) for spinal muscular atrophy(SMA), an autosome recessive disorder. However, it has limitations in SMA diagnosis by Karyomapping, and these methods are unable to distinguish wildtype embryos with carriers effectively. Mutated allele revealed by sequencing with aneuploidy and linkage analyses(MARSALA) is a new method allowing embryo selection by a one-step next-generation sequencing(NGS) procedure, which has been applied in PGD for both autosome dominant and X-linked diseases in our group previously. In this study, we carried out PGD based on MARSALA for two carrier families with SMA affected children. As a result, one of the couples has given birth to a healthy baby free of mutations in SMA-causing gene. It is the first time that MARSALA was applied to PGD for SMA, and we can distinguish the embryos with heterozygous deletion(carriers) from the wild-type(normal) ones accurately through this NGS-based method. In addition, direct mutation detection allows us to identify the affected embryos(homozygous deletion), which can be regarded as probands for linkage analysis, in case that the affected family member is absent. In the future, the NGS-based MARSALA method is expected to be used in PGD for all monogenetic disorders with known pathogenic gene mutation.     

Cystic fibrosis heterozygote screening in 5,161 pregnant women.

A screening program for cystic fibrosis (CF) heterozygotes was conducted in a large HMO prenatal population, to evaluate the level of interest among eligible patients, the effectiveness of prescreening education, attitudes toward the screening process, psychological effects, and utilization of prenatal diagnosis and its outcomes. The heterozygote identification rate and frequency of specific CFTR mutations were also assessed. Identified carriers were offered genetic counseling and testing of male partners. Prenatal diagnosis was offered if both parents were identified as carriers. A total of 5,161 women underwent carrier testing; 947 others completed survey instruments only. The acceptance rate of screening was high (78%), and pretest education by videotape was generally effective. Adverse psychological effects were not reported. Participants generally found screening to be desirable and useful. Screening identified 142 female heterozygotes, 109 couples in which the male partner was not a carrier, and 7 high-risk couples. The incidence of R117H mutations was much higher than expected. The number of identified carriers was much lower in Hispanics than in Caucasians. We conclude that large-scale prenatal screening for CF heterozygotes in the absence of a family history of CF is an acceptable method for identifying couples at risk for affected fetuses. Sufficient pretest education can be accomplished efficiently, test insensitivity is well accepted, adverse psychological events are not observed, and general patient satisfaction is high.     

Twenty-year outcome analysis of genetic screening programs for Tay-Sachs and beta-thalassemia disease carriers in high schools.

Programs for education, screening, and counseling of senior-high-school students, in populations at high risk for Tay-Sachs and beta-thalassemia diseases, have existed for >20 years in Montreal. Four process and outcome variables are reported here: (i) voluntary participation rates in the high-school cohort; (ii) uptake rates for the screening test; (iii) origin of carrier couples seeking the prenatal diagnosis option in the programs; and (iv) change in incidence of the two diseases. Between 1972 and 1992, we screened 14,844 Ashkenazi-Jewish students, identified 521 HexA-deficient carriers (frequency 1:28), reached 89% of the demographic cohort in the educational component of the program, and achieved 67% voluntary participation in the subsequent screening phase. The corresponding data for the beta-thalassemia program are 25,274 students (mainly of Mediterranean origin) representing 67% of the cohort with 61% voluntary participation in the screening phase (693 carriers; frequency 1:36). From demographic data, we deduce that virtually all the carriers identified in the high-school screening program remembered their status, had their partner tested if they did not already know they were a carrier couple, and took up the options for reproductive counseling/prenatal diagnosis. In Montreal, the current origin of all couples using prenatal diagnosis for Tay-Sachs and beta-thalassemia diseases is the corresponding genetic screening/testing program, whereas, at the beginning of the programs, it was always because there was a history of an affected person in the family. Incidence of the two diseases has fallen by 90%-95% over 20 years; the rare new cases are born (with two exceptions) outside the target communities or to nonscreened couples.     

Detection of representative enteropathogenic bacteria, Vibrio spp., pathogenic Escherichia coli, Salmonella spp., Shigella spp., and Yersinia enterocolitica, using a virulence factor gene-based oligonucleotide microarray

Rapid identification of enteropathogenic bacteria in stool samples is critical for clinical diagnosis and antimicrobial therapy. In this study, we describe the development of an approach that couples multiplex PCR with hybridization to a DNA microarray, to allow the simultaneous detection of the 10 pathogens. The microarray was synthesized with 20-mer oligonucleotide probes that were designed to be specific for virulence-factor genes of each strain. The detection limit for genomic DNA from a single strain was approximately 10 fg. In the presence of heterogeneous non-target DNA, the detection sensitivity of the array decreased to approximately 100 fg. We did not observe any non-specific hybridization. In addition, we successfully used this oligonucleotide-based DNA microarray to identify the causative agents in clinical stool samples from patients with food-borne enteritis.     

Metachromatic leukodystrophy in the habbanite Jews: high frequency in a genetic isolate and screening for heterozygotes.

A very high incidence of late infantile metachromatic leukodystrophy (MLD) (1/75 live births) was found in the Jewish Habbanite community which constitutes a genetic isolate of about 1,000-1,200 individuals. Screening in this population for aryl sulfatase A (ASA) levels in married adults revealed a carrier frequency for MLD of 17% and identified six couples of whom both partners were heterozygotes (6% of screened couples). In three pregnancies of these couples, prenatal diagnosis for the detection of ASA in the fetus was performed.     

The aims of expanded universal carrier screening: Autonomy,prevention, and responsible parenthood

Expanded universal carrier screening (EUCS) entails a population‐wide screening offer for multiple disease‐causing mutations simultaneously. Although there is much debate about the conditions under which EUCS can responsibly be introduced, there seems to be little discussion about its aim: providing carrier couples with options for autonomous reproductive choice. While this links in with current accounts of the aim of foetal anomaly screening, it is different from how the aim of ancestry‐based carrier screening has traditionally been understood: reducing the disease burden in the population. The reasons why the aim of EUCS is presented in terms of ‘autonomy’ rather than ‘prevention’ have not been spelled out in the literature. This paper seeks to fill this gap by considering the morally relevant similarities and dissimilarities between foetal anomaly screening, ancestry‐based carrier screening and EUCS. When carrier screening is performed in the prenatal period, enhancing autonomy appears the most appropriate aim of EUCS, as the alternative of ‘prevention through selective abortion’ would urge women to terminate wanted pregnancies. However, when screening is conducted in the preconception period, carrier couples can avoid the birth of affected children by other means than selective abortion, for instance preimplantation genetic diagnosis. To the extent that this increased control over passing on a genetic disorder raises questions of parental responsibility, it seems necessary that the account of the aims of EUCS is wider than only in terms of enhancing reproductive autonomy.