Cystic fibrosis carrier population screening in the primary care setting.

To determine the receptivity of prenatal care providers and their patients to carrier testing for cystic fibrosis (CF), we offered free carrier screening, followed by genetic counseling of carriers, to all prenatal care providers in Rochester, NY, for all their female patients of reproductive age, pregnant or not. Of 124 prenatal care providers, only 37 elected to participate, but many of these offered screening only to pregnant women. The acceptance rate among pregnant women was approximately 57%. The most common reasons for accepting screening were to obtain reassurance (50.7%) and to avoid having a child with CF (27.8 %). The most common reasons for declining screening were not intending to terminate a pregnancy for CF (32.4%) and believing that the chance of having a CF child was very low (32.2%). Compared with decliners, acceptors were more likely to have no children, regarded having a child with CF as more serious, believed themselves more susceptible to having such a child, knew more about CF, would be more likely to terminate a pregnancy if the fetus were shown to have CF, and more strongly supported offering CF screening to women of reproductive age. Of 4,879 women on whom results were obtained, 124 were found to be carriers. Of these 124 carriers, the partners of 106 were tested. Of the five at-risk couples, four requested prenatal diagnosis and one requested neonatal diagnosis. No woman found to be a carrier whose partner tested negative requested prenatal diagnosis. Except for the imperfect knowledge of those testing negative, none of the adverse outcomes predicted for CF carrier testing in the general population were observed in this study.     

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.     

Impact of public health strategies on the birth prevalence of cystic fibrosis in Brittany,France

Taking into account the situation of Brittany, a region of western France where cystic fibrosis (CF) is common and where a neonatal screening program was set up 14 years ago, the aim of this study was to determine the way in which the birth prevalence of CF has been influenced by the various public health strategies implemented in the region (neonatal screening, prenatal diagnosis, ultrasound examination and family testing). This study used the results of the neonatal screening program, which enabled a precise measure of the prevalence of CF at birth to be obtained. Over the same period, we collected data from prenatal diagnoses carried out in the region, first in families related to a CF child and also those made following the detection of an echogenic bowel upon routine ultrasound examination performed during pregnancy. The prevalence of CF at birth was estimated to be 1/2838 in the region over a 10-year period (1992-2001). By including the 54 CF-affected pregnancies that were terminated during these 10 years, the corrected birth prevalence of CF was 1/1972. Prenatal diagnosis was therefore responsible for a global decrease in CF prevalence at birth of 30.5%. This work constitutes the first study able to provide a precise measure of CF birth prevalence and of its evolution through the combined effects of neonatal screening, prenatal diagnosis, ultrasound examination and family testing.     

Activity of enzymes in amniotic fluid in prenatal diagnosis of cystic fibrosis

The activity of microvillar enzymes--gamma-glutamyltranspeptidase, aminopeptidase, general and intestinal forms of alkalyne phosphotases was studied in amniotic fluid (AF) of 33 women with 25% risk of cystic fibrosis (CF) (mucoviscidoses) in their progeny. The figures obtained in this group were compared with corresponding values of the same enzymes in 100 AF samples from normal pregnancies (negative control) and with 9 AF samples from women which were known to give birth to the children with CF (positive control). CF has been predicted in 5 cases, pregnancies were artificially terminated in 4 women. Biochemical CF prediction was proved by immunochemical assay of albumin contents in meconium of fetal ileum. One woman from the high risk group refused abortion and gave birth to a CF child. Among 26 cases of low CF prediction, 13 resulted in birth of a child without a sign of CF, one - in a child with clear-cut diagnosis of CF and 12 other pregnancies still proceed. The efficiency of complex biochemical, pathomorphological and molecular approaches for verification of intrauterine CF diagnosis in aborted fetuses as well as for detection of heterozygous carriers of CF gene and prenatal diagnosis of CF is discussed.     

Cystic fibrosis typing with DNA probes: experience of a screening laboratory

Summary A sample of 125 individuals from 37 British cystic fibrosis (CF) families with at least one living affected child were typed with probes for restriction fragment length polymorphisms (RFLPs) known to be linked to the CF gene. These probes were MetD, MetH, pJ3.11 and 7C22. Using this combination of probes, 30 out of the 37 families were sufficiently informative to enable prenatal diagnosis of the disease. Linkage analysis has also proved to be useful in excluding CF in two cases where diagnosis of the disease was equivocal in the sibling of an affected child.     

Cystic fibrosis: A look into the future of prenatal screening and therapy

Despite recent guidelines suggesting prenatal screening for carriers of cystic fibrosis (CF) mutations, many physicians do not offer patients this service or even counseling. Some argue that the risks of miscarriage associated with prenatal diagnostic techniques outweigh the benefit of added insight, but with the advent of newer, noninvasive techniques, risks of miscarriage may be significantly lowered. Prenatal diagnosis provides parents the time to prepare for raising a child with CF, and soon, could provide treatment options in utero that could improve quality of life. Here, we describe two of the most promising gene therapy approaches: lentivirus and adenoassociated virus (AAV)‐mediated gene transduction. Thus, prenatal detection and treatment is in a most crucial stage for care of patients with CF. Birth Defects Research (Part C) 105:73–80, 2015. © 2015 Wiley Periodicals, Inc.     

Cystic fibrosis typing with DNA probes and screening for ΔF508 deletion in families from Southern France

Summary A sample of 235 individuals from 49 French cystic fibrosis (CF) families with at least one living affected child was typed with probes for restriction fragment length polymorphisms (RFLPs) known to be linked to the CF gene, and was screened for the ΔF508 mutation. Using a combination of six probes, 44 out of the 49 families were sufficiently informative to enable prenatal diagnosis or carrier determination. As in many other populations, linkage disequilibrium was found between the CF locus and the haplotype B (XV2c: allele 1; KM19: allele 2), which accounts for about 78% of CF chromosomes in our families. The ΔF508 deletion was present in 64.3% of CF chromosomes.     

Reproductive management through integration of PGD and MPS-based noninvasive prenatal screening/diagnosis for a family with GJB2-associated hearing impairment

A couple with a proband child of GJB2(encoding the gap junction protein connexin 26)-associated hearing impairment and a previous pregnancy miscarriage sought for a reproductive solution to bear a healthy child. Our study aimed to develop a customized preconception-to-neonate care trajectory to fulfill this clinical demand by integrating preimplantation genetic diagnosis(PGD), noninvasive prenatal testing(NIPT), and noninvasive prenatal diagnosis(NIPD) into the strategy. Auditory and genetic diagnosis of the proband child was carried out to identify the disease causative mutations. The couple then received in-vitro-fertilization treatment, and eight embryos were obtained for day 5 biopsy. PGD was performed by short-tandem-repeat linkage analysis and Sanger sequencing of GJB2 gene. Transfer of a GJB2 c.235del C heterozygous embryo resulted in a singleton pregnancy. At the 13 th week of gestation, genomic DNA(g DNA) from the trio family and cell-free DNA(cf DNA) from maternal plasma were obtained for assessment of fetal chromosomal aneuploidy and GJB2 mutations. NIPT and NIPD showed the absence of chromosomal aneuploidy and GJB2-associated disease in the fetus, which was later confirmed by invasive procedures and postnatal genetic/auditory diagnosis. This strategy successfully prevented the transmission of hearing impairment in the newborn, thus providing a valuable experience in reproductive management of similar cases and potentially other monogenic disorders.     

Prenatal diagnosis of cystic fibrosis by assay of amniotic fluid microvillar enzymes

Summary Activities of the microvillar enzymes -glutamyl-transpeptidase (GGTP), aminopeptidase M (APM), phosphodiesterase and maltase have been examined in second-trimester amniotic fluid as possible aids to the early prenatal diagnosis of cystic fibrosis (CF). The two peptidases, GGTP and APM, gave best results. If the fifth percentile of the normal range is used as an action line, the sensitivity of a positive test (low GGTP value) is 78% and the predictability 84%. At the tenth percentile the sensitivity is 100% and the predictability 77%. These approximate figures apply only to pregnancies where there has been a previous affected child. Until the primary protein defect in CF is discovered, this may prove an acceptable form of prenatal diagnosis to the high-risk mother.     

Spectrum of cystic fibrosis mutations in Serbia and Montenegro and strategy for prenatal diagnosis

We have screened 175 patients for molecular defects in the cystic fibrosis transmembrane conductance regulator (CFTR) gene using nondenaturing polyacrylamide gel electrophoresis (PAGE), denaturing gradient gel electrophoresis (DGGE), and sequencing. Six different mutations (F508del, G542X, 621+1G --> T, 2789+5G --> A, R1070Q, and S466X) accounted for 79.71% of CF alleles, with the F508del mutation showing a frequency of 72.28%. Another 12 mutations (R334W, 2184insA, I507del, 1525-1G --> A, E585X, R75X, M1I, 457TAT --> G, 574delA, 2723delTT, A120T, and 2907delTT) covered an additional 3.36%. A novel mutation (2723delTT) was found in one CF patient (F508del/2723delTT). Thus, a total of 18 mutations cover 82.57% of CF alleles. During our study, 72% of families at risk for having a CF child were found to be fully informative for prenatal diagnosis. Prenatal diagnosis was performed on 56 families; 76 analyses resulting in 16 affected, 38 carriers, and 22 healthy fetuses. These results imply that the molecular basis of CF in Serbia and Montenegro is highly heterogeneous, as is observed in other eastern and southern European populations. Because we detected more then 80% of CFTR alleles, results could be used for planning future screening and appropriate genetic counseling programs in our country.     

Cystic fibrosis in the Portuguese population: haplotype distribution and molecular pathology

Summary The aim of this study was to obtain an estimate of the frequency of the ΔF508 mutation in the Portuguese population, and of the tightness of its association with specific haplotypes. Furthermore, the genotype/clinical phenotype relationship and the feasibility of prenatal diagnosis were also investigated. The analysis of 42 cystic fibrosis (CF) families revealed that (1) 52% of CF chromosomes carry the deletion of codon 508; (2) there seems to be a positive correlation between the occurrence of the ΔF508 mutation and the severity of the disease; and (3) fully informative prenatal diagnosis can be offered in 76% of at-risk pregnancies by using both genomic and allele specific oligonucleotide probes.     

Prenatal screening for cystic fibrosis carriers: an economic evaluation.

The cloning of the CFTR gene has made it technically possible to avert the unwanted birth of a child with cystic fibrosis (CF). Several large trials offering prenatal CF carrier screening suggest that such screening is practical and that identified carriers generally use the information obtained. Therefore, a critical question is whether the cost of such screening is justified. Decision analysis was performed that used information about choices that pregnant women were observed to make at each stage in the Rochester prenatal carrier-screening trial. The cost of screening per CF birth voluntarily averted was estimated to be $1,320,000-$1,400,000. However, the lifetime medical cost of the care of a CF child in today's dollars was estimated to be slightly>$1,000,000. Therefore, despite both the high cost of carrier testing and the relative infrequency of CF conceptions in the general population, the averted medical-care cost resulting from choices freely made are estimated to offset approximately 74%-78% of the costs of a screening program. At present, if it is assumed that a pregnancy terminated because of CF is replaced, the marginal cost for prenatal CF carrier screening is estimated to be $8,290 per quality-adjusted life-year. This value compares favorably with that of many accepted medical services. The cost of prenatal CF carrier screening could fall to equal the averted costs of CF patient care if the cost of carrier testing were to fall to $100.     

Carrier detection and prenatal diagnosis of cystic fibrosis using an intragenic TA-repeat polymorphism

Summary We have analysed the segregation of a TA-repeat polymorphism in intron 17b of the cystic fibrosis transmembrane conductance regulator gene responsible for cystic fibrosis (CF) in 23 French CF families non-informative for the F508 mutation (i.e. with at least one parent not carrying F508) or closely linked DNA markers. At least 13 different alleles ranging from 7 to 45 repeats were observed and the detected heterozygosity was 89%. Of the 23 families studied, 19 were fully informative for prenatal diagnosis or carrier detection, 3 were partially informative and one was not informative. In 6 families, prenatal diagnosis for CF or carrier detection in siblings of CF cases were performed using this polymorphism.     

Cystic fibrosis: typing 48 German families with linked DNA probes

Summary Two hundred and thirty five subjects from 48 German cystic fibrosis (CF) families were typed for restriction fragment length polymorphisms (RFLPs) detected by the probes pmet H, pmet D, and pJ 3.11, known to be tightly linked to the CF gene. Gene and haplotype frequencies suggest a linkage disequilibrium with the CF locus. The analysis of the predictive value of this typing in individual CF families indicates that the combined use of these probes provides a powerful diagnostic system both for carrier detection and prenatal diagnosis. In 33 out of 48 families carriers and non-carriers could be identified, and in 26 of these 33 families prenatal diagnosis could discriminate between affected and unaffected offspring.     

Linkage disequilibrium, cystic fibrosis, and genetic counseling.

Strong linkage disequilibrium occurs between the cystic fibrosis (CF) locus and polymorphisms detected with the DNA probes XV-2c and KM-19. In a North American population, 86% of CF chromosomes occur with a haplotype which occurs on only 14% of normal chromosomes. An individual homozygous for the highest-risk haplotype has an 81-fold greater probability of carrying a CF allele than does an individual homozygous for the lowest-risk haplotype. The linkage-disequilibrium data can be used for prenatal diagnosis and genetic counseling in CF families. The data are useful in 1-in-4-risk pregnancies when DNA is not available from the propositus and in counseling close relatives of CF families. Serious problems arise with some pregnancies which remain at intermediate risks after analysis, and families are left with difficult decisions. It is not clear that genetic testing for couples at less than 1-in-4 risk is cost-effective or standard care, but use of linkage-disequilibrium data will provide more accurate risk probabilities in a substantial proportion of cases if such testing is carried out. Our results emphasize the need for a specific biological or molecular carrier test. This experience in using linkage-disequilibrium and linkage data in combination for genetic counseling provides a model system for the diagnosis of other disorders.     

Prenatal diagnosis of spinal muscular atrophy in Macedonian families

Spinal muscular atrophy (SMA) is the second most common lethal autosomal recessive disorder of childhood, affecting approximately 1 in 6,000-10,000 births, with a carrier frequency of 1 in 40-60. There is no effective cure or treatment for this disease. Thus, the availability of prenatal testing is important. The aim of this study was to establish an efficient and rapid method for prenatal diagnosis of SMA and genetic counseling in families with risk for having a child with SMA. In this paper we present the results from prenatal diagnosis in Macedonian SMA families using direct analysis of fetal DNA. The probands of these families were previously found to be homozygous for a deletion of exons 7 and 8 of SMN1 gene. DNA obtained from chorionic villas samples and amniocytes was analyzed for deletions in SMN gene. SMN exon 7 and 8 deletion analysis was performed by polymerase chain reaction/restriction fragment length polymorphism (PCR/RFLP). Of the 12 prenatal diagnoses, DNA analysis showed normal results in eight fetuses. Four of the fetuses were homozygote for a deletion of exons 7 and 8 of SMN1. After genetic counseling, the parents of the eight normal fetuses decided to continue the pregnancy, while in the four families with affected fetuses, the pregnancy was terminated. The results were confirmed after birth.     

Prenatal hemoglobinopathy screening. IV. Follow-up of women at risk for a child with a clinically significant hemoglobinopathy.

To determine the benefits and burdens of prenatal hemoglobinopathy carrier identification and genetic counseling and its impact on subsequent reproductive behavior, we recontacted women whom we had previously identified as at risk for having a child with a clinically significant hemoglobinopathy, regardless of whether they had accepted the offer of prenatal diagnosis. Of the 46 such women, 31 were available for interview. These 31 women had received offers of prenatal diagnosis in 47 pregnancies. Seventeen had been accepted, and 30 had been declined. The proportion of patients accepting the offer of prenatal diagnosis was higher for the index pregnancy (50%) than for subsequent pregnancies (22%). The mean interval between the initial counseling of the patient and the follow-up interview was 43 mo (standard error +/- 2.7 mo). Ninety-four percent of those interviewed recalled having received information from the screening program; 74% recalled the name of their condition; 90% knew that trait did not affect their health; 84% recalled the name of the condition for which their fetus had been at risk; and 77% could state at least one symptom of the disease. Of the 29 women asked whether they intended to use prenatal diagnosis in future pregnancies, 13 said yes and 16 said no. Of the 26 patients asked about satisfaction with their previous decision about prenatal diagnosis, all were satisfied with their decision. Eighteen said they would make the same decision in their next pregnancy, but seven patients said they would not, and one was undecided.(ABSTRACT TRUNCATED AT 250 WORDS)     

Further data supporting linkage between cystic fibrosis and the met oncogene and haplotype analysis with met and pJ3.11

The linkage of cystic fibrosis (CF) and the polymorphic DNA markers pJ3.11, met, 7C22, DOCR1-917, COL1A2, and TCRB have jointly localized the mutation causing CF to chromosome 7q2.1-3.1. We report further linkage data with two polymorphic markers at the met oncogene locus, pmetH and pmetD, which supports the tight linkage found by White et al. between CF and met. One family shows evidence for meiotic recombination between CF and met. Analysis of haplotypes in CF pedigrees collected for linkage studies combined with data from single affected families requesting prenatal diagnosis (Farrall et al., Lancet i:1402-1404, 1986) shows CF and met to be in linkage equilibrium in our population while pJ3.11-CF haplotypes show a deviation from the equilibrium frequencies.     

Carrier screening for cystic fibrosis in a prenatal setting

Maternal prenatal cystic fibrosis (CF) screening was offered from September, 1997, to April, 1999, at the Ghent University Hospital, to couples undergoing prenatal diagnosis (amniocentesis) for reasons not related to CF. Fifteen minutes were devoted to explaining CF, CF screening, and the study protocol. The purpose was to assess the short- and long-term knowledge of CF, the attitude towards carrier screening, and carriership. A total of 314 couples entered the pilot study; 13 female CF carriers were identified. None of their partners carried an identifiable mutation. Our survey results show that information about CF and CF screening can be given effectively as part of antenatal care because most couples recalled important medical and genetic issues, valued the genetic test for CF, and seemed to cope well with the results. Risk estimates and actual numbers were more difficult to process and recall. From the small number of couples in which the woman alone was found to be a carrier, there was little or no evidence of marked distress.     

Involving consumers in the development of an educational program for cystic fibrosis carrier screening.

Input from consumers of health care was sought in developing an educational program to be provided to individuals who are considering carrier testing for cystic fibrosis (CF). In addition, we assessed the ability of health professionals to predict consumers' priorities with regard to such information. A focus group of six middle school teachers formulated questions that they would ask in trying to decide whether they wanted carrier screening for CF. Then, other adults with (n = 39) and without (n = 60) a family history of CF were presented with the questions and were asked to select the questions in the order in which they would want them answered if offered the carrier test. After each question was answered, they were asked whether they would want the carrier test if it were offered to them. CF clinic staff, clinical geneticists, and genetic counselors (n = 31) were asked to select the questions in the order in which they believed that an adult from the general population would want them answered. There were no differences in the order in which adults with and without a family history of CF would want questions answered. Consumers would want to learn about the carrier test as well as their risk of being a carrier and of having a child with CF, before receiving information on reproductive options and the effect that a child with CF would have on the family. Of the 44% of consumers who changed their mind about wanting screening during the course of selecting questions, 52% did so after the first question that they selected.(ABSTRACT TRUNCATED AT 250 WORDS)