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At-risk persons' attitudes toward presymptomatic and prenatal testing of Huntington disease in Michigan.

One hundred fifty-five individuals at 50% risk of inheriting Huntington disease (HD) were given a questionnaire surveying their sociodemographic characteristics, experience with HD, and attitudes toward presymptomatic and prenatal testing in HD. About two-thirds (63.2%) of the persons indicated they would take a presymptomatic test even if no specific treatment was available. Although one-half (49%) of the respondents stated they would make use of a prenatal test, only 43% of these individuals would decide to terminate a heterozygous fetus. Presymptomatic test results indicating carrier status would influence some of the respondents' decisions about marriage and childbearing. This strong interest of at-risk persons to make use of both presymptomatic and prenatal diagnosis in HD indicates the need for well-organized testing programs. These programs must be designed to address the genetic, psychosocial, and ethical issues that may arise in the use of this type of genetic test.

Adult↗

Prenatal testing for Huntington's disease: a European collaborative study.

This European study involving seven genetic centres from six countries - Aberdeen, Cardiff (UK), Leiden (Netherlands), Leuven (Belgium), Paris (France), Rome (Italy), Athens (Greece) has gathered information on prenatal testing by direct mutation analysis and exclusion testing for Huntington's disease (HD) from the six European countries during the period 1993-1998. Data describing the parent belonging to the HD family was collected; this included their sex and age as well as their risk of developing HD. Information about previous pregnancies, the rank of the pregnancy being tested and its outcome was also gathered. In addition the number of previous prenatal tests for HD was recorded. Three hundred and five results were recorded by the participating countries between 1993 and 1998. The largest groups came from the UK (157) and the Netherlands (90). The mean age for the parent from the HD family was 30.8 years. In half of the tests the prospective parent was an asymptomatic gene carrier, 42% remained at risk, and 6% of the prospective parents were already showing clinical features of HD. 65% of tests performed used mutation analysis.

Adolescent↗

Full karyotyping, rapid aneuploidy diagnosis or both when invasive prenatal testing is performed for diagnosis of thalassaemia?

A retrospective study was performed to compare the detection rate of chromosomal abnormalities by different approaches of full karyotyping, rapid aneuploidy diagnosis (RAD) or both when invasive prenatal testing is performed for diagnosis of thalassaemia. The karyotype results of 1120 prenatal samples obtained from thalassaemia couples from January 1985 to December 2002 in a referral centre for prenatal diagnosis were studied. The detection rate of chromosomal abnormalities by four different approaches were compared: (i) karyotyping for all samples; (ii) RAD (21,18,13,X,Y) for all samples; (iii) RAD for all samples + karyotyping for cases with ultrasound abnormalities; and (iv) RAD (21,18,13) for all + RAD (X,Y) for cases with ultrasound abnormalities consistent with Turner syndrome + karyotyping for cases with ultrasound abnormalities. Normal karyotypes were found in 1103 samples (98.5%). There were 17 cases (1.5%) of chromosomal abnormalities: four cases (0.36%) were clinically significant, eight cases (0.7%) were of borderline clinical significance and five cases (0.44%) were not confirmed by subsequent prenatal or postnatal tests. The incidences of autosomal (7/1120 = 0.63%) and sex chromosomal (5/1120 = 0.45%) abnormalities were not higher than those (0.41 and 0.22%, respectively) from newborn surveys (Hook and Hamerton, 1977) (P = 0.398 and 0.216, respectively). Approach 1 would detect all 17 chromosomal abnormalities. Approach 2 would detect three of four clinically significant chromosomal abnormalities but not detect six of eight chromosomal abnormalities of borderline clinical significance and three of five chromosomal abnormalities not confirmed by subsequent prenatal or postnatal tests. Approach 3, in addition, would be able to detect all four clinically significant chromosomal abnormalities. Approach 4 would detect all four clinically significant chromosomal abnormalities but would not detect seven of eight chromosomal abnormalities of borderline clinical significance and four of five chromosomal abnormalities not confirmed by subsequent prenatal or postnatal tests. RAD (21,18,13) for all + RAD (X,Y) for cases with ultrasound abnormalities consistent with Turner syndrome + karyotyping for cases with ultrasound abnormalities seemed to be the best approach for the detection of chromosomal abnormalities when invasive prenatal testing is performed for diagnosis of thalassaemia.

Adolescent↗

Prenatal testing in ICSI pregnancies: incidence of chromosomal anomalies in 1586 karyotypes and relation to sperm parameters.

BACKGROUND: Prenatal testing was offered in all pregnancies obtained after ICSI with ejaculated or non-ejaculated sperm as part of the evaluation of the safety of ICSI. METHODS: Between 1990 and 2001, a chorionic villus sampling (CVS) or amniocentesis was offered for multiple or singleton pregnancies respectively during a genetic counselling session for all couples applying for ICSI. ICSI was carried out using ejaculated, epididymal or testicular sperm. RESULTS: In total, 1586 ICSI fetuses obtained after fresh embryo transfer were tested by CVS (n = 698) or by amniocentesis (n = 888). Abnormal fetal karyotypes were found in 47 samples [3.0%; 95% confidence interval (CI) 2.2-3.9%]; 25 anomalies (1.6%; 95% CI 1.0-2.3%) were de novo. These were 10 sex chromosomal anomalies and 15 autosomal anomalies [either numerical (n = 8) or structural (n = 7)], and 22 inherited abnormalities (1.4%; 95% CI 0.9-2.1%) (21 balanced, one unbalanced). In 17/22 inherited cases the chromosomal structural defect was inherited from the father. A significantly higher percentage of 2.1% de-novo prenatal chromosomal anomalies was observed for sperm concentrations of <20x10(6) sperm per ml, as compared with 0.24% if the sperm concentration was vertical line 20x10(6) sperm per ml (Fisher's exact test, P = 0.006). No statistical difference in frequency of chromosomal anomalies was observed for lower threshold values of sperm concentration (<1x10(6), <5x10(6), <10x10(6) and <15x10(6)). A statistical difference was observed for motility criteria, but not morphology. Three chromosomal anomalies were found prenatally after use of epididymal or testicular sperm in a total of 94 samples; two (of 83 tested) were from patients with obstructive and one (of nine tested) was from a patient with non-obstructive azoospermia. CONCLUSIONS: A significantly higher rate of de-novo chromosomal anomalies (1.6 versus 0.5% in amniocentesis for a mean maternal age of 33.5 years; P < 0.007) was observed in ICSI offspring, relating mainly to a higher number of sex chromosomal anomalies and partly to a higher number of autosomal structural anomalies. This finding was related to sperm concentration and motility. The significantly higher rate of observed inherited anomalies (1.4 versus 0.3-0.4% in prenatal tests in the general population; P < 0.001) was related to a higher rate of constitutional chromosomal anomalies, mainly in the fathers. The hypothesis of a higher risk of post-zygotic events as a consequence of the ICSI procedure leading to a higher proportion of chromosomal mosaicism was not confirmed in this study. Couples should be informed of the risks of an abnormal result related to sperm quality, and of the risk linked to a prenatal procedure as well as about the relatively benign character of some chromosomal anomalies such as de-novo structural anomalies or sex chromosomal anomalies in order to be able to make a choice for prenatal testing, or not.

Adult↗

DNA based prenatal testing for the skin blistering disorder epidermolysis bullosa simplex.

Epidermolysis bullosa simplex (EBS) is a skin fragility disorder in which mild physical trauma leads to blistering. The phenotype of the disorder is variable, from relatively mild affecting only the hands and/or feet, to very severe with widespread blistering. For the severest forms of EBS there is a demand for prenatal diagnosis which until now has involved a fetal skin biopsy in the second trimester. The identification of mutations in the genes encoding keratins K5 and K14 as the cause of EBS opens up the possibility of much earlier diagnosis of the disease. We report here four cases in which prenatal testing was performed. In three of the cases the genetic lesions were unknown at the start of the pregnancy, requiring the identification of the causative mutation prior to testing fetal DNA. In two of the four cases novel mutations were identified in K14 and in the two remaining families, a previously identified type of mutation was found. Fetal DNA, obtained by chorionic villus sampling or amniocentesis, was analysed for the identified mutations. Three of the DNA samples were found to be normal; a mutant K14 allele was identified in the fourth case and the pregnancy was terminated. These results demonstrate the feasibility of DNA-based prenatal testing for EBS in families where causative mutations can be found.

Amino Acid Sequence↗

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.

Abortion, Habitual↗

Prenatal testing and pregnancy termination in Sri Lanka: views of medical students and doctors.

INTRODUCTION: Prenatal diagnosis and pregnancy termination generate complex ethical issues. Surveys conducted in Sri Lanka among doctors and medical students in 1986 supported a change in law in favour of pregnancy termination when gross genetic defects are detected antenatally. A new generation of prenatal tests has focused attention again on the topic of termination and under what circumstances it might be legally done. The present survey contributes to the debate by means of a survey of doctors and medical students. METHOD: A self-administered questionnaire given to doctors and medical students. RESULTS: Ninety three per cent of doctors and 81% of students accept pregnancy termination as an appropriate course of action if a gross genetic defect is detected antenatally, and 87% of doctors and 80% of students support a change in the law to allow termination of the pregnancy. The corresponding figures in previous surveys were 80%, 69% and 96%, 88% respectively. CONCLUSIONS: A majority of doctors and medical students support a change in law in favour of liberalising pregnancy termination when a genetic defect is detected antenatally.

Abortion, Induced↗

An inevitable dilemma: prenatal testing for mutations in the BRCA1 breast-ovarian cancer susceptibility gene.

The BRCA1 breast-ovarian cancer susceptibility gene was identified recently. Germline mutations in BRCA1 may be responsible for as many as 5% of breast and ovarian cancers. Inherited alterations confer up to a 94% risk of developing breast and/or ovarian cancer by age 70. With the discovery of BRCA1, there will be a heavy demand for genetic testing. Because of the large size of the gene and the distribution of reported mutations, scientists face considerable technical problems in developing widely available screening tests; clinicians will face even greater ethical problems in applying them. In the context of research programs, women with BRCA1 mutations are already being identified, and their physicians are confronted with a number of complex medical, ethical, legal, and social issues. Obstetricians will be faced with counseling parents regarding prenatal testing for specific BRCA1 mutations. Although it is difficult to formulate straightforward guidelines regarding prenatal BRCA1 testing, clinicians and health care providers must be familiar with the nuances of the debate so that these issues can be discussed wisely with patients. As with many ethically challenging problems in medicine, individual clinicians and their patients will have to work together to determine the course of action with which they are most comfortable. Although elective termination of a pregnancy with a germline mutation in BRCA1 is an option, experience with other adult-onset diseases suggests that only a minority of parents will choose this option.

BRCA1 Protein↗

Impact of prenatal testing on maternal-fetal bonding: chorionic villus sampling versus amniocentesis.

The process of maternal-fetal attachment, considered vital for normal infant development, begins during pregnancy and can be affected by a number of external factors. In this study the impact of prenatal testing on maternal-fetal bonding was evaluated in 253 women undergoing either first-trimester chorionic villus sampling (n = 101) or second-trimester genetic amniocentesis (n = 152). The women were evaluated by means of a modification of the Cranley Maternal-Fetal Attachment Scale, administered before and after the results of the prenatal diagnostic testing were made known to them (mean gestational ages of 10.6 and 15.7 weeks for the chorionic villus sampling group and 16.5 and 21.1 weeks for the amniocentesis group). The results showed: (1) that maternal-fetal attachment begins as early as 10 weeks' gestation and increases significantly as the pregnancy progresses, (2) that maternal-fetal attachment increases significantly, once the results are known to be normal, for both groups (p less than 0.001), (3) that this increase occurs about 5 weeks earlier for patients with chorionic villus sampling in comparison to those undergoing amniocentesis (p less than 0.001). Thus, with regard to the process of maternal-fetal attachment, first-trimester chorionic villus sampling appears to be preferable to second-trimester amniocentesis.

Amniocentesis↗

Tomorrow's prenatal genetic testing. Should we test for 'minor' diseases?

New genetic knowledge will make it possible to test prenatally for a wide range of fetal genetic characteristics. One consequence will be an expansion of potential reasons for selective abortion following prenatal testing. It will likely become possible for patients to request prenatal testing and abortion not only for serious diseases but also relatively mild diseases, late-onset diseases, treatable diseases, elevated risks for common diseases, and eventually nondisease characteristics, such as height and body build. Two main ethical views concerning prenatal testing have been advocated: (1) Prenatal testing should be restricted to the "most severe" disorders, involving profound retardation, severe physical handicaps, or prolonged physical suffering and (2) Patients' requests for prenatal tests should be honored except for diseases considered to be "too minor." At least two additional views can be identified: (3) Physicians should honor requests for prenatal testing for diseases, including relatively minor ones, but not requests pertaining to nondisease characteristics and (4) All requests for prenatal tests should be honored. A difficulty with the first and second views is that they deviate from the norm of nondirectiveness in prenatal testing and counseling. The problems with the fourth view are that it leads to abortions for morally trivial reasons and that attempts to design our children could adversely affect parent-child relationships and exacerbate current social inequities. These considerations support the third view, which holds that the future role of reproductive genetic testing and counseling should be based on the imperfect, but helpful, distinction between disease and nondisease.

Ethics, Medical↗

Women's and health professionals' preferences for prenatal testing for Down syndrome in Australia.

AIM: To describe and compare women's and health professionals' preferences for prenatal screening tests for Down syndrome. DESIGN: Cross-sectional questionnaire survey. PARTICIPANTS AND SETTING: Women (n = 322) attending for a glucose challenge test at 26 weeks gestation and health professionals (266 midwives and 34 obstetricians) at the Royal Women's Hospital, Melbourne, between 13 December 2002 and 30 April 2003. OUTCOME MEASURES: The relative value participants attach to attributes of Down syndrome screening tests as determined by conjoint analysis and ranking scales. RESULTS: Women and health professionals shared similar relative values regarding the importance of detection rate of screening tests, according to coefficients from conjoint analysis models. However, health professionals placed higher relative values on timing of prenatal tests and risk associated with the subsequent diagnostic test than did women. Comparison of coefficients suggests that, compared with health professionals, women would wait longer and accept a greater decrease in detection rate for a test if it was safer. Using the more traditional ranking scale, the safest test was ranked first by 56% of women while 47% of health professionals ranked a test with the highest detection rate first. Equal proportions ( approximately 10%) in both groups ranked the earliest test first. CONCLUSION: There is a general agreement between pregnant women and health professionals regarding the relative importance they attach to different attributes of a test. However, health professionals appeared to favour earlier timing of tests while women placed greater emphasis on safety. Utilising two different measures of preference demonstrated the complexity of decision-making.

Adolescent↗

Transmission ratio distortion in the spinal muscular atrophy locus: data from 314 prenatal tests.

BACKGROUND: Spinal muscular atrophy (SMA) is a recessive neurodegenerative disorder characterized by the loss of alpha-motor neurons in the spinal cord and subsequent death of motor neuron cells. SMA occurs with a frequency of 1 in 6,000 live births, with a carrier frequency of 1 in 40, and is a leading genetic cause of infant mortality. SMA is caused by loss or mutation of the telomeric survival motor neuron gene (SMN1), which is deleted in almost 94% of SMA patients OBJECTIVE: To analyze the transmission ratio at the SMA locus, examining the segregation of the SMN1-deleted alleles in 314 fetuses from carrier parents who requested prenatal testing for the disease. METHODS: Prenatal diagnosis of SMA in families at 25% risk of the disease has been performed on chorionic villous sampling specimens, through direct detection of the SMN1 gene mutation and linkage analysis using microsatellite markers from the 5q13 region. Analysis of the genotypic/allelic frequencies of the SMN1 gene was performed using the chi2 test, assuming a recessive mendelian inheritance. RESULTS: Of 314 fetuses analyzed, 95 were homozygous for the wild-type allele (30.3%), 154 were carriers (49.0%), and the remaining 65 were homozygous for the mutated allele (20.7%). Statistical analysis demonstrated that proportion of fetuses predicted with SMA is lower than 25% expected for a recessive disorder, resulting in a transmission rate of the SMN1-deleted allele deviant from the 50% expected in a random the segregation of a mendelian tract (p = 0.016) CONCLUSIONS: This is the first study to evaluate the genotypic frequencies at the spinal muscular atrophy (SMA) locus based on data derived from prenatal analysis, which are not subject to ascertainment bias. The analysis showed a transmission ratio distortion at the SMA locus in favor of the SMN1 wild-type alleles.

Chorionic Villi Sampling↗

Effects of maternal age and education on the pattern of prenatal testing: implications for the use of antenatal screening as a solution to the growing number of amniocenteses.

OBJECTIVE: This study was undertaken to assess age-specific effects of maternal education on patterns of prenatal testing. STUDY DESIGN: We used data from a sample of all births in France in 1998. Statistical analysis included logistic regression and likelihood ratio tests. RESULTS: The rate of amniocentesis of women without serum screening was 7.3% for those with 12 years or less, and 16.7% for those with more than 12 years of education. Women with lower levels of education were about 50% more likely to have an amniocentesis if they had serum screening (odds ratio [OR], 1.5; 95% CI, 1.2-1.8). In contrast, women with higher levels of education were less likely to have an amniocentesis with screening (OR, 0.7; 95% CI, 0.6-0.8); the education effect persisted across maternal age groups. CONCLUSION: Many women eligible for reimbursed serum screening, in particular those with higher levels of education, obtain amniocentesis without serum screening. This might limit the use of antenatal screening as a solution to the growing number of amniocenteses.

Adult↗

Educating general practitioners about prenatal testing: approaches and challenges.

OBJECTIVES: To examine the effects of an education intervention on the knowledge and practice behaviours of general practitioners (GPs) regarding prenatal screening and diagnostic testing in Melbourne, Australia. METHODS: A single group, pre-test, repeated post-test design was used. Information on demographics, knowledge, behaviours and skills was collected via a self-administered questionnaire prior to the educational intervention. Responses to individual questions were coded and scores calculated, as well as a percent total score. Following the education, data were again collected, immediately afterwards (Post-Q) and six-to-eight months later (Foll-Q). RESULTS: Data for all three time points were collected from 63 GPs and showed a variable, and relatively poor knowledge regarding aspects of prenatal testing, especially before education. The percent mean total score at baseline was 51.2+/-1.59% (CI 48.02 to 54.39), which increased significantly (p<0.001) in both Post-Q (62.88+/-1.51%; CI 59.86 to 65.89) and Foll-Q (58.92+/-1.6%; CI 55.71 to 62.12). CONCLUSION: The educational intervention significantly increased knowledge and practice behaviour of GPs, even up to eight months later, but this could be improved further, to a considerable extent. There is a need for ongoing multi-faceted approaches to educating GPs on prenatal testing to ensure that they are engaged in appropriate practice.

Adult↗

Parental decisions to abort or continue a pregnancy with an abnormal finding after an invasive prenatal test.

OBJECTIVE: To determine the importance of various factors on the decisions whether to terminate or continue a pregnancy after an abnormal result. METHODS: The decisions of 1467 women who had an abnormal result after an invasive prenatal test were examined according to their religion, the time of diagnosis and the severity of the disorder. RESULTS: When the examinations were performed by chorionic villus sampling (CVS) among both Jews and non-Jews most of the women opted to terminate the affected pregnancy. After amniocentesis the rate of termination of pregnancy was still very high among cases in which Down syndrome or other significant chromosomal aberrations were diagnosed among Jews. For all the other diagnostic groups either among Jews or non-Jews there was a significant proportion of the cases in which the women decided to continue the pregnancy. A significant exception about the decisions of the couples was in the case of hemoglobinopathy-affected pregnancies among Arabs since both after CVS and amniocentesis many women often decided to continue the pregnancy. CONCLUSION: The main factor in the decision to terminate or continue the pregnancy is the severity of the disorder diagnosed. However, among Arabs other factors are important, in particular the time at which the diagnosis is made.

Abortion, Eugenic↗

Procedure-related miscarriages and Down syndrome-affected births: implications for prenatal testing based on women's preferences.

OBJECTIVE: To determine how pregnant women of varying ages, races, ethnicities, and socioeconomic backgrounds value procedure-related miscarriage and Down-syndrome-affected birth. METHODS: We studied cross-sectionally 534 sociodemographically diverse pregnant women who sought care at obstetric clinics and practices throughout the San Francisco Bay area. Preferences for procedure-related miscarriage and the birth of an infant affected by Down syndrome were assessed using the time trade-off and standard gamble metrics. Because current guidelines assume that procedure-related miscarriage and Down syndrome-affected birth are valued equally, we calculated the difference in preference scores for those two outcomes. We also collected detailed information on demographics, attitudes, and beliefs. RESULTS: On average, procedure-related miscarriage was preferable to Down syndrome-affected birth, as evidenced by positive differences in preference scores for them (time trade-off difference: mean = 0.09, median = 0.06; standard gamble difference: mean = 0.11, median = 0.02; P <.001 for both, one-sample sign test). There was substantial subject-to-subject variation in preferences that correlated strongly with attitudes about miscarriage, Down syndrome, and diagnostic testing. CONCLUSION: Pregnant women tend to find the prospect of a Down syndrome-affected birth more burdensome than a procedure-related miscarriage, calling into question the equal risk threshold for prenatal diagnosis. Individual preferences for those outcomes varied profoundly. Current guidelines do not appropriately consider individual preferences in lower-risk women, and the process for developing prenatal testing guidelines should be reconsidered to better reflect individual values.

Abortion, Spontaneous↗

Prenatal testing for late infantile neuronal ceroid lipofuscinosis.

Classic late infantile neuronal ceroid lipofuscinosis (LINCL) is a neurodegenerative disease in which autofluorescent "curvilinear" storage bodies accumulate in tissues from affected patients. Recently, the LINCL gene (CLN2) has been found to code for a pepstatin-insensitive lysosomal protease whose activity is deficient in LINCL specimens. We report the first 2 cases of successful prenatal testing for LINCL by using DNA and enzyme-based methods on amniocytes, and describe a new private mutation in one of the families analyzed. These approaches allow definitive prenatal diagnosis and represent a significant improvement over previous pathological methods.

Adult↗

Genetic analysis of a severe case of Netherton syndrome and application for prenatal testing.

Netherton syndrome (NS) is a rare autosomal recessive disease with variable expression. It is defined by a triad of symptoms: congenital ichthyosiform erythroderma, trichorrhexis invaginata and atopy. Recently, genetic linkage has been established to the SPINK5 gene locus on chromosome 5q32 encoding the serine protease inhibitor LEKTI. In this study, we present a recurrent homozygous mononucleotide deletion (153delT) resulting in a severe case of NS exhibiting exfoliative erythroderma with lethal outcome at the age of 4 months and its application in prenatal testing in a subsequent pregnancy of the mother.

Carrier Proteins↗