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PubMed2003

First report of prenatal diagnosis of genetic congenital deafness in a routine prenatal genetic test.

OBJECTIVE: We aimed to screen for connexin26 gene (GJB2) mutations associated with autosomal recessive non-syndromic neurosensory deafness (NSRD) in a general risk population. METHODS: Screening for the most common connexin26 gene mutations was offered to all women undergoing a second-trimester amniocentesis for fetal karyotype analysis in our Center. After rapid DNA extraction from amniotic fluid, PCR amplification was performed and products analysed to detect mutations of GJB2 gene by a sequencing technique. In particular, we searched for the 20 most frequently reported mutations (out of the approximately 90 so far described) and for which there are commercially available tests. RESULTS: From a total of 4819 consecutive amniotic fluids examined, the following five different heterozygous mutations were detected: 35delG in 80 cases, 167delT in 3 cases and 1 occurrence of each of the following mutations: M34T, 35insG and W77R. From these data, a prevalence of 1 : 56 (1.78%) for the heterozygous condition can be estimated in the Mediterranean general risk population. The striking predominance of 35delG mutation is confirmed. In addition, we detected a homozygous 35delG mutation condition in a foetus of no risk parents. In this case, the early diagnosis permitted prompt application of an acoustic prosthesis allowing for cochlear implantation in due time, with significant improvement of the prognosis. CONCLUSIONS: In a general risk population, a carrier status for congenital deafness can be observed in 1 : 56 (1.78%) amniotic fluids; this is mostly due to the presence of a 35delG mutation of the connexin26 gene. Occasional identification of homozygous states, although rare, allows the best therapeutic approach.

Connexin 26↗
PubMed1999

The gene encoding hydroxypyruvate reductase (GRHPR) is mutated in patients with primary hyperoxaluria type II.

Primary hyperoxaluria type II (PH2) is a rare monogenic disorder that is characterized by a lack of the enzyme that catalyzes the reduction of hydroxypyruvate to D-glycerate, the reduction of glyoxylate to glycolate and the oxidation of D-glycerate to hydroxypyruvate. The disease is characterized by an elevated urinary excretion of oxalate and L-glycerate. The increased oxalate excretion can cause nephrolithiasis and nephrocalci-nosis and can, in some cases, result in renal failure and systemic oxalate deposition. We identified a glyoxylate reductase/hydroxypyruvate reductase (GRHPR) cDNA clone from a human liver expressed sequence tag (EST) library. Nucleotide sequence analysis identified a 1198 nucleotide clone that encoded a 984 nucleotide open reading frame. The open reading frame encodes a predicted 328 amino acid protein with a mass of 35 563 Da. Transient transfection of the cDNA clone into COS cells verified that it encoded an enzyme with hydroxy-pyruvate reductase, glyoxylate reductase and D-glycerate dehydrogenase enzymatic activities. Database analysis of human ESTs reveals widespread tissue expression, indicating that the enzyme may have a previously unrecognized role in metabolism. The genomic structure of the human GRHPR gene was determined and contains nine exons and eight introns and spans approximately 9 kb pericentromeric on chromosome 9. Four PH2 patients representing two pairs of siblings from two unrelated families were analyzed for mutations in GRHPR by single strand conformation polymorphism analysis. All four patients were homozygous for a single nucleotide deletion at codon 35 in exon 2, resulting in a premature stop codon at codon 45. The cDNA that we have identified represents the first characterization of an animal GRHPR sequence. The data we present will facilitate future genetic testing to confirm the clinical diagnosis of PH2. These data will also facilitate heterozygote testing and prenatal testing in families affected with PH2 to aid in genetic counseling.

Alcohol Oxidoreductases↗
PubMed2003

The "new genetics" and clinical practice.

A "new genetics" has emerged driven by knowledge gained at the DNA level. In clinical practice, a practical application of the new genetics is DNA testing, which can be expected to expand with the completion of the Human Genome Project as the functions of new genes are discovered. Genetic DNA testing scenarios include diagnostic DNA testing, prenatal DNA testing, predictive (presymptomatic) DNA testing and screening DNA testing. The challenge for genetic DNA testing and clinical practice will be to define the roles to be played by the general practitioner, the specialist, and other healthcare professionals. From the patients' and families' perspective, the new genetics will best be implemented if a planned approach is adopted in the ordering of DNA tests and the associated counselling and support processes.

DNA↗
PubMed1999

Evaluation of the enzyme test for the detection of clinically significant red blood cell antibodies during pregnancy.

In the Croatian transfusion medicine, no general agreement has yet been achieved whether red blood cell (RBC) Rhesus (Rh) antibodies detected during pregnancy only by enzyme tests can cause hemolytic disease of the newborn (HDN). Results of the detection of clinically significant RBC antibodies by low-ionic-strength additive solution antiglobulin test (LISS-IAT) and trypsin enzyme test in 22,947 pregnant women are presented. All pregnant women in whom clinically significant RBC antibodies (RBC-CSA) were detected by LISS-IAT and/or enzyme tests were followed and observed during pregnancy. The women who had enzyme-only anti-D antibodies in their serum were followed up during subsequent pregnancies. Out of 302 positive results obtained by both techniques, irregular clinically significant enzyme-only antibodies (anti-RhD and anti-RhE specificity) were detected in 14 (4.6%) pregnant women. None of 11 RhD positive newborns whose mothers had enzyme-only anti-D antibodies, had signs of HDN after delivery. In these 11 women, anti-D antibodies were detected by LISS-IAT in the first trimenon of subsequent pregnancy. Nine infants born from subsequent pregnancies to women who had previously had enzyme-only anti-D, had clinical signs of HDN. The authors concluded that there is no need for enzyme tests in prenatal testing because enzyme tests are not reliable in the prediction of HDN.

Blood Group Antigens↗
PubMed1988

Guidelines for using five new prenatal laboratory tests.

All physicians, even those not routinely involved in prenatal care, should be aware of the laboratory tests recently recommended for inclusion in prenatal care. All pregnant women should undergo blood glucose testing to detect gestational diabetes mellitus. Women at risk for hepatitis B, Chlamydia trachomatis infection, or human immunodeficiency virus infections should be tested. All women should also be offered alpha fetoprotein testing for detection of neural tube defects. If test results are abnormal, appropriate management and/or counseling should be provided.

Acquired Immunodeficiency Syndrome↗
PubMed2005

Reliable test for prenatal prediction of fetal RhD type using maternal plasma from RhD negative women.

OBJECTIVES: The objective of this study was to establish a reliable test for prenatal prediction of fetal RhD type using maternal plasma from RhD negative women. This test is needed for future prenatal Rh prophylaxis. METHODS: A novel real-time PCR-based assay targeting RHD exon 7 combined with a published assay for RHD exon 10 were used to determine the fetal RHD status in DNA extracted from plasma, sampled from 56 pregnant RhD negative women in 15th-36th week of gestation. Thirty-eight samples were from ongoing pregnancies of Danish women and 21 samples from 18 pregnant women were stored anonymized samples from the International Blood Group Reference Laboratory, Bristol, United Kingdom. Prediction of fetal RhD type was compared with the serological result obtained after birth. RESULTS: The prediction of the fetal RhD type was in 100% concordance with the serological RhD type from the 16th week of gestation. One sample from the 15th week of gestation was inconclusive. The number of copies of fetal RHD DNA was found to increase with gestational age. Low levels of DNA were found to follow the Poisson distribution (p = 1.0000). CONCLUSION: Our set-up was very reliable for determination of fetal RhD genotype, and thus will be of value in prenatal Rh prophylaxis and in the management of immunized women.

DNA↗
PubMed2000

Paradox of a better test for Huntington's disease.

OBJECTIVES: To describe the consequences of the identification of the Huntington's disease (HD) mutation on predictive and prenatal testing. METHODS: A retrospective study was performed considering the test applicants, procedures, and results before and after the identification of the mutation. 1032 people at risk for Huntington's disease in The Netherlands were included, of whom 741 applied for the predictive test in the period 1987 to 1997 in Leiden at the Department of Clinical Genetics, and after 1994, also in the other seven clinical genetics departments in The Netherlands. Uptake, sociodemographic variables, and test results, taken before and after the mutation was identified, are described. RESULTS: The uptake of the predictive test in the period studied was 24% and for the prenatal test 2%. No differences were noted in numbers and sociodemographic data between the period before and after the mutation was identified. After an initial increase in test applicants, a decrease was seen after 1995. After 1993 a significant increase of 25% at risk test applicants and a significant decrease of prenatal exclusion tests was noticed. Only 7% asked for reassessment by mutation analysis. New problems arose after the identification of the mutation, such as the option of reassessing the risk obtained by linkage analysis, direct mutation testing of 25% at risk persons with a parent who does not wish to know, new choices regarding reproduction, and new uncertainties for carriers of intermediate and reduced penetrance alleles and for their offspring and relatives. CONCLUSIONS: Although predictive testing has become reliable and available for every person at risk since the mutation has been identified, the uptake of predictive and prenatal tests fell short of expectation, no change in sociodemographic variables was seen, and a decrease in number of applicants was noted. Furthermore, new uncertainties, psychological problems, and questions arose.

Adult↗
PubMed2007

Molecular testing for Fragile X Syndrome: lessons learned from 119,232 tests performed in a clinical laboratory.

PURPOSE: To examine the data from over 119,000 Fragile X Syndrome tests and 307 prenatal tests to detect unsuspected findings and obtain clinical data when indicated to optimize genetic counseling. METHODS: A proprietary database containing 119,232 consecutive postnatal and 307 prenatal FXS tests performed between November 2, 1992 and June 1, 2006 was queried. RESULTS: The distribution of normal FMR1 alleles was a bimodal distribution with a major peak at 30 repeats and a minor peak at 21 repeats. Of 59,707 tests performed for males, 1.4% had a fully expanded and methylated FMR1 allele. Of 59,525 tests performed for females, 0.61% had an affected FMR1 allele, and 1.7% had a premutation FMR1 allele for a total carrier frequency of 1.3%. When fetuses inherited an expanded maternal allele, the risk of expansion to a full affected allele was 0%, 5%, 30% and 100% for allele sizes of <50, 50-75, 76-100 and >100 repeats, respectively. CONCLUSIONS: These figures can be used for genetic counseling of patients presenting for carrier detection and prenatal diagnosis for Fragile X Syndrome.

Adult↗
PubMed2005

Preimplantation genetic diagnosis for aneuploidy screening in women older than 37 years.

OBJECTIVE: To provide background information about the average aneuploidy and implantation rates of older patients after IVF with preimplantation genetic diagnosis for aneuploidy screening (PGD-AS) when the patients are subdivided into age categories; and to compare pregnancy outcome data after PGD-AS in this group of patients with a similar control group. DESIGN: Retrospective clinical study. SETTING: Patients in an academic reproductive medicine unit. PATIENT(S): All patients 37 years or older who had PGD-AS between October 1999 and December 2003 and all pregnant patients 37 years or older who had IVF/intracytoplasmic sperm injection without PGD-AS during the same period of time. INTERVENTION(S): IVF with PGD-AS. MAIN OUTCOME MEASURE(S): Aneuploidy rate, miscarriage rate, live birth rate, implantation rate, multiple pregnancy rate, and prenatal testing. RESULT(S): Three hundred ninety-four PGD-AS cycles of patients between 37 and 46 years of age were analyzed. The aneuploidy rate gradually increased with age. The implantation rate remained similar over all age groups. There was a trend to a lower miscarriage and multiple pregnancy rate in the PGD-AS group and a higher delivery/live birth rate. There were five elective terminations of pregnancy after prenatal testing and three late miscarriages due to prenatal testing in the control group. CONCLUSION(S): Preimplantation genetic diagnosis for aneuploidy screening can give valuable information to older patients concerning the reason why their IVF cycles are unsuccessful and whether it is worthwhile to continue IVF treatment, and it can help patients to avoid the emotional trauma that can occur after prenatal testing during the second trimester of pregnancy.

Adult↗
PubMed1990

Carrier testing and prenatal diagnosis for hemophilia: experiences and attitudes of 549 potential and obligate carriers.

Experiences with and attitudes toward carrier testing and prenatal diagnosis were evaluated among 549 potential and obligate carriers of hemophilia. Almost everybody considered carrier testing to be useful. Forty-nine percent had been tested for carriership, 10% had only received limited information, and 41% had not been tested and had never received information about the heredity of hemophilia. More married women, women with severe hemophilia in their family, and women closely related to a patient with hemophilia had been tested for carriership than others. Lack of information about the probability of carriership for female relatives and a similar ignorance of the possibility of carrier testing were important reasons for not having been tested. Eleven percent of the women with one or more children had undergone prenatal diagnosis in the past. Thirty-one percent of the study population would favour prenatal diagnosis with the implication of a potential abortion in early pregnancy and half of them would choose this option even in late pregnancy. Most of the women who objected to prenatal diagnosis did so because they did not consider hemophilia to be a sufficiently serious disorder to justify an abortion.

Abortion, Therapeutic↗
PubMed2000

Economic issues in the prevention of vertical transmission of HIV.

In the absence of interventions, 20% of infants born to women infected with HIV acquire infection from their mother at or before delivery. A further 15% are infected through breast feeding. Prenatal testing for HIV allows infected women to be reliably identified so that they can receive antiretroviral therapy and, in countries with safe water supplies, be advised not to breast feed. These and other interventions can reduce the risk of transmission to 5% or less. Economic evaluations of prenatal testing for HIV are reviewed and compared in this article, and future research priorities outlined. These studies set the costs of testing and intervention against the averted lifetime costs of paediatric infection, and generate estimates of the HIV prevalence threshold above which there would be a net cost saving, or calculate the cost per life-year saved given a particular prevalence. In the developed world, prenatal testing has been adopted in many countries, and recent economic analyses broadly support this. Future research is likely to focus on the incremental benefits of different antiretroviral regimens in lowering transmission rates still further, with or without elective caesarean section, and the possibility that some may lead to adverse effects in uninfected infants exposed to them in utero. Some earlier assessments in resource-poor settings concluded that prenatal testing was unaffordable or of doubtful cost effectiveness. This negative conclusion appears to be the result of very low estimates of the lifetime costs of paediatric HIV infection, together with developed world conceptions of pre-test counselling. The demonstration that nevirapine reduces transmission risk at a low cost has transformed the outlook, and there is hope that antiretrovirals can act prophylactically to prevent infection of the breast-fed child. However, to achieve a sustained reduction in vertical transmission there may be a need to evaluate the need for a strengthened infrastructure to deliver prenatal HIV testing and treatment, as well as programmes to reduce HIV incidence in adults.

HIV Infections↗
PubMed1999

An epidemic of congenital syphilis in Jefferson County, Texas, 1994-1995: inadequate prenatal syphilis testing after an outbreak in adults.

OBJECTIVES: After a syphilis epidemic in Jefferson County, Texas, in 1993 and 1994, congenital syphilis prevalence and risk factors were determined and local prenatal syphilis screening practices were assessed. METHODS: Medical records were reviewed, pregnant women with syphilis were interviewed, and prenatal care providers were surveyed. RESULTS: Of 91 women, 59 (65%) had infants with congenital syphilis. Among African Americans, the prevalence per 1000 live births was 24.1 in 1994 and 17.9 in 1995. Of the 50 women with at least 2 prenatal care visits who had infants with congenital syphilis, 15 (30%) had received inadequate testing. Only 16% of 31 providers obtained an early third-trimester syphilis test on all patients. CONCLUSIONS: Inadequate prenatal testing contributed to this outbreak of congenital syphilis.

Adolescent↗
PubMed1992

Prenatal literature testing: a pilot project.

A pilot study was conducted in 1987-1988 to evaluate current health literature utilized for prenatal health education of the high risk population in County Health Departments in Arizona. Towards that end, sixty-five distinct pamphlets were obtained from Arizona's County Health Departments and assessed for reading level using the SMOG Readability Formula. The majority of the prenatal literature were found to be 10th to 12th grade reading level, higher than the typical reading level of the high risk prenatal population. A modified literature testing instrument was further utilized to test eight general prenatal pamphlets to assess the printed literature for accuracy, usability, believability, appeal, and cultural relevance. Four pamphlets of those tested, two English and two Spanish, were identified as being the most appropriate for the high risk prenatal population.

Arizona↗
PubMed1994

Ethical issues related to prenatal genetic testing. The Council on Ethical and Judicial Affairs, American Medical Association.

This report examines ethical issues related to prenatal genetic testing, including the physician's role in promoting informed reproductive decisions and physician involvement in genetic selection and manipulation. In general, it would be ethically permissible to participate in genetic selection (abortion or embryo discard) or genetic manipulation to prevent, cure, or treat genetic disease. It would not be ethical to engage in selection on the basis of benign characteristics. Genetic manipulation of benign traits, though generally unacceptable, may be permissible under exceptional circumstances. At a minimum, three criteria would have to be satisfied: there would have to be a clear and meaningful benefit to the child, there could be no trade-off with other characteristics or traits, and all citizens would have to have equal access to the genetic technology, irrespective of income or other socioeconomic characteristics.

Abortion, Therapeutic↗
PubMed2005

Rapid prenatal diagnostic testing for Down syndrome only or longer wait for full karyotype: the views of pregnant women.

OBJECTIVES: Prenatal diagnosis by karyotype analysis determines the copy number and structure of each chromosome and is considered to be the 'gold standard' in detection of chromosome abnormality. This method is, however, time consuming and women may have to wait up to 21 days for the results. With improving molecular genetic techniques, the most commonly occurring chromosome abnormalities can be diagnosed within 2 days from amniotic fluid. This study investigates the value pregnant women place on these alternative prenatal diagnostic tests. METHODS: A structured self-completion discrete choice experiment questionnaire was designed. The subjects were 40 pregnant women, of unknown risk, attending for their 11-week booking scan and 10 elevated-risk women attending for amniocentesis at the Aberdeen Maternity Hospital, Scotland. RESULTS: Women value 'comprehensive' information of a full karyotype analysis at pounds 791, and 'simple' information of a rapid diagnostic test at pounds 690. Willingness to pay for a day's reduction in waiting time for results is pounds 18. Women prefer a prenatal service providing simple over comprehensive information as long as they receive results 6 days sooner than the comprehensive results would be provided. CONCLUSIONS: While women prefer comprehensive information, the bulk of the value is placed on knowing whether the fetus has Down syndrome. Given the longer wait times for comprehensive information, simple information is preferred as long as results are received 6 days sooner than would be the case for comprehensive information. These results have implications for the resources dedicated to providing a rapid prenatal diagnostic service.

Adolescent↗
PubMed1999

Preimplantation genetic diagnosis and the 'new' eugenics.

Preimplantation genetic diagnosis (PID) is often seen as an improvement upon prenatal testing. I argue that PID may exacerbate the eugenic features of prenatal testing and make possible an expanded form of free-market eugenics. The current practice of prenatal testing is eugenic in that its aim is to reduce the numbers of people with genetic disorders. Due to social pressures and eugenic attitudes held by clinical geneticists in most countries, it results in eugenic outcomes even though no state coercion is involved. I argue that technological advances may soon make PID widely accessible. Because abortion is not involved, and multiple embryos are available, PID is radically more effective as a tool of genetic selection. It will also make possible selection on the basis of non-pathological characteristics, leading, potentially, to a full-blown free-market eugenics. For these reasons, I argue that PID should be strictly regulated.

Ethics, Medical↗
PubMed2002

Prenatal HIV testing in private OB-Gyn practices in Texas.

This study evaluates the prenatal human immunodeficiency virus (HIV) testing behaviors of private obstetrics and gynecology practitioners in Texas. A statewide telephone survey of 614 providers of prenatal care determined the level of HIV testing, how testing is offered, and patient acceptance of the test. Ninety-nine percent of the practices offered HIV testing to all their pregnant patients, and 96% of the practices included HIV testing in the routine panel of tests for pregnant patients. More than 95% of the practices reported that 10% or less of the women refused the test when offered it; 73% of the practices reported no refusals. Less than half of the practices, however, discussed HIV prevention topics, and only 29% of the practices referred high-risk pregnant patients for prevention counseling. Although private practices of obstetrics and gynecology report testing almost all their prenatal patients, survey results suggest that providers could improve their prevention and patient education practices.

AIDS Serodiagnosis↗
PubMed1996

Racial-ethnic differences in prenatal diagnostic test use and outcomes: preferences, socioeconomics, or patient knowledge?

OBJECTIVE: To determine whether use of chorionic villus sampling and amniocentesis varies by racial-ethnic group and, if so, whether this variation is reflected in the prevalence of Down syndrome-affected births to women age 35 and older, the ages at which prenatal diagnosis is offered currently. METHODS: Medical charts of 238 women 35 years of age and older presenting for care at the University of California at San Francisco by 20 gestational weeks in 1993 and 1994 were reviewed to assess prenatal diagnostic test use. The prevalence of Down syndrome-affected births in California during 1983-1991 was obtained from the Birth Defects Monitoring Program. RESULTS: Latinas and African-American women were much less likely to undergo prenatal diagnosis than were whites and Asians. Odds ratio (OR) and 95% confidence intervals (CI), with white women serving as the reference group, were as follows: Asians 1.16 (0.57-2.36), Latinas 0.19 (0.08-0.43), and African-Americans 0.19 (0.04-0.49). Trends persisted, at diminished magnitude, after adjustment for socioeconomic characteristics: OR for Asians 1.77 (0.78-3.98) Latinas 0.28 (0.09-0.83) , and African-Americans 0.33 (0.10-1.10). Non-white women age 35 and older were significantly more likely than white women to give birth to a Down syndrome-affected infant: risk ratios for Asians 1.81 (1.61-2.03), Latinas 3.00 (2.74-3.28), and African-Americans 1.86 (1.63-2.11). CONCLUSION: Racial-ethnic differences exist in prenatal diagnostic test use and associated outcomes in women aged 35 and older. Socioeconomic factors are partially responsible; patient education and preferences may play a role.

Adult↗