The impact of genetic counselling on females in fragile X families.

We report a retrospective study over the period 1981-1992 of the reproductive histories of 27 women, from 21 families, who were known or possible fragile X carriers. Eighteen women had cytogenetic and DNA linkage studies to establish their carrier risk. They subsequently received definitive carrier status information following the cloning of the gene in 1991. The remaining nine women had cytogenetic and mutation studies only. For 11 of the women their carrier risk was modified over the 11 year period. The results suggest that these women at risk of having a son with fragile X have carefully considered their reproductive choices. Three of the six women who were initially sterilised have had, or are awaiting, a reversal of sterilisation following clarification of their carrier status. There were 10 pregnancies to 10 women. Seven of the pregnancies were to women at "high" (40-100%) risk of being a carrier, and in this group only one woman chose to continue the pregnancy without prenatal diagnosis. Three pregnancies were to women at "medium" or "low" (< 39%) risk of being a carrier. None of the three chose prenatal diagnosis and one affected male was born to this group.     

Postmenopausal hormone replacement in the woman with a reproductive risk factor for breast cancer

Objective: to assess the interaction between postmenopausal hormone replacement therapy (HRT) and various reproductive risk factors for breast cancer such as early menarche, late menopause, late first delivery and nulliparity. Design: three cohort studies and fourteen case control studies, published between 1975 and 1997, provided relative risks (RRs) of HRT use in women with, as well as in those without, a reproductive risk factor for breast cancer. Methods: using an additive RR model reported before, we investigated whether the RR for breast cancer in women with a combination of HRT and a given reproductive risk factor result from a simple addition of RRs of HRT on the one hand, and of the pre-existing reproductive risk factor on the other hand, or that synergism between both risk factors occurs. Results: simple addition of RRs was shown in the case of early menarche and late menopause. Less increase of risk, suggesting antagonism, was found for both late first delivery and nulliparity in combination with HRT use. Conclusion: we could not observe any synergistic effect of the combined risks of any of the following reproductive risk factors for breast cancer: early menarche, late menopause, late first delivery or nulliparity on the one hand, with the risk resulting from HRT use on the other hand. Therefore, as far as the risk of breast cancer is concerned, the use of HRT appears not to be highly detrimental in women with a reproductive breast cancer risk factor, as it results in not more than a simple addition of risks at the most.     

Measuring quality of patient information documents with an expanded EQIP scale

OBJECTIVE: To develop an expanded version of the ensuring quality information for patients (EQIP) scale to measure quality of patient information documents. METHODS: We added 16 new items to the 20-item EQIP scale. The 36 items addressed document content, structure, and identification data. The new tool was used to rate the quality of 73 leaflets describing medical care procedures, used at a university hospital. Assessment rules were clarified on 25 documents; the remaining 48 leaflets were independently rated by two assessors. RESULTS: Inter-rater reliability was very good (mean item-specific kappa statistic on 48 documents=0.84). The intraclass correlation coefficient for the global score was 0.95. The mean global conformity score on all items was 44 (range: 21-76, S.D.=10). Most documents stated the purpose of the medical intervention (74% fully adequate), described qualitative risks (64%), used a respectful tone (80%), provided clear information (64%) in a logical order (73%). Fewer quantified risks (7%), were balanced (33%), used everyday language (22%), provided contact details (28%), identified authors (25%) and funding sources (4%). None gave evidence-based references nor clearly mentioned patient participation. CONCLUSIONS: The expanded EQIP scale was reliable, and proved useful for analysis of patient information documents. Documents partially met international standards for quality patient information. PRACTICE IMPLICATIONS: Document producers' efforts should focus on respecting guidelines and including patients.     

Informed consent documents for BRCA1 and BRCA2 screening: how large is the readability gap?

The decision to undergo testing for the BRCA1 and BRCA2 mutations, which are associated with an increased risk of breast and ovarian cancer, can have long-term consequences on women's lives. Women who decide to undergo such testing are required to sign informed consent documents, which indicate that they understand the test and its risks and benefits. These documents are generally written for advanced-level readers. However, the reading abilities of many women are substantially lower than the level of the consent forms, resulting in a 'readability gap'. This disparity suggests that women may not fully understand the documents they are asked to sign. The 'readability gap' poses the serious issues about informed consent, raising questions about institutional review boards and the effectiveness of the documents that are currently in use.     

311例孕中期羊膜腔穿刺产前诊断研究

目的通过孕中期羊膜腔穿刺羊水染色体核型分析结果,探讨胎儿染色体异常的临床高危因素,提高临床医师对羊水染色体核型分析产前诊断指征的认识。方法对311例孕16～28w有产前诊断指证的孕妇在B超定位下行羊膜腔穿刺术,抽取羊水进行培养、G显带染色及染色体核型分析。结果共检出染色体核型异常13例,占4.18%。其中孕妇或丈夫为染色体异常者中5例（5/6）,高龄孕妇（年龄≥35岁）中4例（4/161）,有21-三体或18-三体生育史孕妇中1例（1/30）,年龄〈35岁,唐氏综合征血清学筛查高危孕妇中2例（2/87）,畸形儿生育史孕妇中1例（1/1）,单纯超声＂软指标＂及无产前诊断指征自愿要求孕妇中未检出染色体核型异常。结论羊水染色体核型分析是诊断胎儿染色体病的有效手段。夫妇有一方为染色体异常、孕妇高龄、唐氏综合征血清学筛查高危、非整倍体儿及畸形儿生育史均为胎儿染色体异常的临床高危因素,应引起临床医师的高度重视。     

Live-birth rates and multiple-birth risk of assisted reproductive technology pregnancies conceived using thawed embryos,USA 1999-2000

BACKGROUND: Increasing use of assisted reproductive technology treatments has been associated with the current rise in multiple births in the USA. Embryo cryopreservation and subsequent thawed embryo transfer may favourably impact the multiple-birth risk by relieving some pressure that patients and providers may feel to transfer several embryos in a single cycle. The study objective was to examine both live-birth rates and multiple-birth risk in thawed cycles. METHODS: The authors used a population-based sample of 21 555 assisted reproductive technology procedures performed in US clinics in 1999 and 2000 that used thawed embryos derived from the patient's oocytes. RESULTS: Both patient age and the number of embryos transferred were independent predictors of live birth. Even among women aged 20-29 years, the transfer of three embryos resulted in an increase in the live-birth rate compared with cycles in which one or two embryos were transferred. This increase in success was accompanied by an increased multiple-birth risk. In all age groups up to 40 years, the transfer of just two embryos resulted in a multiple-birth risk of 16-17%. The multiple-birth risk increased with the number of embryos transferred. CONCLUSIONS: Patient age and the number of embryos transferred significantly affect live-birth and multiple-birth rates among women who use thawed embryos.     

Policies of academic medical centers for disclosing financial conflicts of interest to potential research participants.

PURPOSE: To document the current state of institutional review board (IRB) and conflict of interest committee policies regarding disclosures of financial conflicts of interest to potential research participants, and to use this information to identify and share models for effectively achieving disclosure. METHOD: The authors identified the 123 U.S. academic medical centers that have IRBs and sought their IRB and institutional policies regarding financial conflicts of interest. In February and March 2004, using manual and key word searches, each institution's Web site was searched to identify documents containing information regarding the disclosure of financial conflicts of interest. Letters were sent to 24 institutions that had either no information or incomplete information posted on their Web sites. To assess institutions' guidelines for disclosure, the authors extracted and content coded each institution's information on disclosure. RESULTS: Relevant information was obtained from 120 (98%) academic medical centers (AMCs), of which 57 (48%) mentioned disclosing financial conflicts to potential research participants. Of these 57, 33 (58%) included verbatim language that could be used in informed consent documents. AMCs' recommendations and requirements for disclosure included details of the financial arrangement, administrative management of conflicts of interest, and encouragement of dialogue between the investigator and the potential research participant. CONCLUSIONS: Considerable variability exists concerning the specific information that should be disclosed. Most of the AMCs' policies were consistent with the goal of protection from legal liability. Significant questions remain, however, concerning the goals of disclosure and the most effective methods for achieving those goals.     

Selenium status, pregnancy outcomes, and mother-to-child transmission of HIV-1

BACKGROUND: Among HIV-infected pregnant women, low selenium status may increase risk of mother-to-child transmission (MTCT) of HIV and poor pregnancy outcomes (low birthweight, small for gestational age, preterm birth, and fetal death) through several mechanisms, such as by promoting maternal HIV disease progression, viral shedding in the genital tract, and development of mastitis. However, there is no direct epidemiologic evidence on these relations among HIV-infected pregnant women. OBJECTIVE: To investigate the association between selenium status during pregnancy and pregnancy outcomes, MTCT of HIV, and child mortality. DESIGN: Baseline plasma selenium measurements from HIV-positive pregnant women (n = 670) were obtained between 12-27 weeks of gestation and mother-child pairs were followed prospectively until 24 months after delivery. RESULTS: Low plasma selenium levels were associated with increased risks of fetal death, child death, and HIV transmission through the intrapartum route. Low selenium status was not associated with risks of low birthweight or preterm birth but was associated with an apparently lower risk of small for gestational age. CONCLUSION: Adequate selenium status may be beneficial for some but not all pregnancy outcomes. Further studies are needed to better understand the role of selenium status in pregnancy outcomes, HIV transmission, and child health.     

Duchenne muscular dystrophy in Wales: a 15 year study, 1971 to 1986.

A register of families with Duchenne muscular dystrophy (DMD) in Wales was set up in 1973 and has been regularly maintained ever since. All women at significant risk in these families were offered estimation of their carrier status by creatine kinase and pedigree analysis. A total of 225 of the 512 women tested was assigned a risk of carrying the DMD gene of less than 5%. One hundred and twenty live births from this group were notified to the register and only one was an affected male. This was the expected number and shows that the risks given were largely accurate. Women given a risk of 5% or greater were offered fetal sexing with termination of any male. Amniocentesis was of limited value and chorionic villus sampling, introduced in 1984, was acceptable to more women at risk. The incidence of DMD in Wales dropped from one in 3435 at the beginning of the study to one in 4046 by 1982, and the proportion of recurrent cases from 40% to 22%. Common reasons for recurrence were birth of a second affected boy before diagnosis of the first, and failure of families with affected dead members in previous generations to be notified to the register. Maintaining an accurate register of DMD families is an essential tool in their management.     

An audit of consent refusals in clinical research at a tertiary care center in India

Background and Rationale:

Ensuring research participants’ autonomy is one of the core ethical obligations of researchers. This fundamental principle confers on every participant the right to refuse to take part in clinical research, and the measure of the number of consent refusals could be an important metric to evaluate the quality of the informed consent process. This audit examined consent refusals among Indian participants in clinical studies done at our center.

Materials and Methods:

The number of consent refusals and their reasons in 10 studies done at our center over a 5-year period were assessed. The studies were classified by the authors according to the type of participant (healthy vs patients), type of sponsor (investigator-initiated vs pharmaceutical industry), type of study (observational vs interventional), level of risk [based on the Indian Council of Medical Research (ICMR) “Ethical Guidelines for Biomedical Research on Human Participants”], available knowledge of the intervention being studied, and each patient''s disease condition.

Results:

The overall consent refusal rate was 21%. This rate was higher among patient participants [23.8% vs. healthy people (14.9%); P = 0.002], in interventional studies [33.6% vs observational studies (7.5%); P < 0.0001], in pharmaceutical industry-sponsored studies [34.7% vs investigator-initiated studies (7.2%); P < 0.0001], and in studies with greater risk (P < 0.0001). The most common reasons for consent refusals were multiple blood collections (28%), inability to comply with the study protocol (20%), and the risks involved (20%).

Conclusion:

Our audit suggests the adequacy and reasonable quality of the informed consent process using consent refusals as a metric.KEY WORDS: Autonomy, consent, India, reason, refusal, risk     

The effect of format modifications and reading comprehension on recall of informed consent information by low-income parents: a comparison of print, video, and computer-based presentations

A randomized trial comparing the amount of knowledge orally recalled from four different presentations of the same consent information was conducted in a non-clinic sample of 233 low-income parents who displayed a range of reading comprehension skill. The study simulated recruitment of children into one of two actual studies underway at another location: one involved high risk to participants, the other did not. Use of a non-clinic sample controlled for prior knowledge of the conditions, and avoiding discussion of the information further assured that differences in recalled information could be attributed more confidently to the format itself. The formats included the original written forms, enhanced print (simpler language, topic headings, pictures), narrated videotapes, and self-paced PowerPoint presentations via laptop computer with bulleted print information, pictures, and narration. No format-related differences in recalled information were found in the full sample but for the 124 individuals with reading comprehension scores at or below the 8th grade level, the enhanced print version tended to be more effective than either the original form or the video. Across all formats, more information was recalled about the low-risk study. The findings emphasize the necessity for clinicians and researchers to verify understanding of consent information, especially when there is risk of reduced literacy skill. Reliance on video to convey information in preference to well-done print media appeared questionable.     

Framing procedural risks to patients: is 99% safe the same as a risk of 1 in 100?

PURPOSE: A patient's willingness to consent to a procedure may be influenced by various factors, including the patient's rapport with the physician, nonverbal cues he or she receives during the discussion of risks, and other elements of the discussion of risks. Previous reports address these influences, but the effect of the actual wording used to describe risks is unclear. The purpose of this study was to better understand how framing the risk involved in a procedure affects a patient's likelihood to consent to the procedure. METHOD: In a 1997 study at the Cleveland Clinic Foundation, the authors randomly assigned 116 patients to view one of two short videos describing angioplasty and its associated risks. Sixty-three participants viewed the first video, which framed the procedure as 99% safe, and 53 viewed the second, which framed the likelihood of complication as 1 in 100. Participants were then asked to rate their consent to two hypothetical treatment scenarios on a four-point Likert-type scale (1 = definitely, 4 = definitely not). RESULTS: When asked to consent to a treatment scenario that would relieve chest pain but offer no survival benefit, respondents who viewed the first video were more likely to consent than were those who viewed the second (p<.001). There was no significant difference in the two groups' likelihoods to consent when the potential health benefit was to reduce the risk of future heart attack. CONCLUSION: This study's finding provides evidence that how a physician describes a procedure's risks when obtaining a patient's informed consent significantly influences the likelihood of consent. This fact should be considered when teaching communication skills, including interviewing and patient education skills, so that patients will be more likely to make health care decisions that are consistent with their own values and beliefs.     

Mutations in coagulation factors in women with unexplained late fetal loss

BACKGROUND: Factor V and prothrombin-gene mutations are independent risk factors for venous thrombosis; it is debated whether a mutation in the gene encoding methylenetetrahydrofolate reductase, an enzyme involved in homocysteine metabolism, also increases the risk of venous thrombosis. Whether any of these mutations is associated with an increased risk of late fetal death is not known. METHODS: We studied 67 women with a first episode of unexplained late fetal loss (fetal death after 20 weeks or more of gestation) and 232 women who had had one or more normal pregnancies and no late fetal losses. All the women were tested for the presence of three gene mutations. Women with other thrombophilic conditions were excluded from the study. RESULTS: Eleven of the 67 women with late fetal loss (16 percent) and 13 of the 232 control women (6 percent) had either the factor V or the prothrombin mutation. The relative risks of late fetal loss in carriers of the factor V and prothrombin mutations were 3.2 (95 percent confidence interval, 1.0 to 10.9) and 3.3 (95 percent confidence interval, 1.1 to 10.3), respectively. Thirteen percent of the women whose fetuses died and 20 percent of the control women were homozygous for the mutation in the methylenetetrahydrofolate reductase gene (relative risk, 0.8; 95 percent confidence interval, 0.5 to 1.2). CONCLUSIONS: Both the factor V and the prothrombin mutations are associated with an approximate tripling of the risk of late fetal loss.     

How psychotherapists handle treatment errors – an ethical analysis

In studies publishing identifying personal information, obtaining consent is regarded as necessary, as it is impossible to ensure complete anonymity. However, current journal practices around specific points to consider when obtaining consent, the contents of consent forms and how consent forms are managed have not yet been fully examined. This study was conducted to identify potential issues surrounding consent to publish identifying personal information. Content analysis was carried out on instructions for authors and consent forms developed by academic journals in four fields (as classified by Journal Citation Reports): medicine general and internal, genetics and heredity, pediatrics, and psychiatry. An online questionnaire survey of editors working for journals that require the submission of consent forms was also conducted. Instructions for authors were reviewed for 491 academic journals (132 for medicine general and internal, 147 for genetics and heredity, 100 for pediatrics, and 112 for psychiatry). Approximately 40% (203: 74 for medicine general and internal, 31 for genetics and heredity, 58 for pediatrics, and 40 for psychiatry) stated that subject consent was necessary. The submission of consent forms was required by 30% (154) of the journals studied, and 10% (50) provided their own consent forms for authors to use. Two journals mentioned that the possible effects of publication on subjects should be considered. Many journal consent forms mentioned the difficulties in ensuring complete anonymity of subjects, but few addressed the study objective, the subjects’ right to refuse consent and the withdrawal of consent. The main reason for requiring the submission of consent forms was to confirm that consent had been obtained. Approximately 40% of journals required subject consent to be obtained. However, differences were observed depending on the fields. Specific considerations were not always documented. There is a need to address issues around the study objective, subjects’ right to refuse consent and the withdrawal of consent. Whether responsibility for ensuring that the consent form has been signed lies with publishers also needs to be discussed.     

The application of linkage analysis to genetic counselling in families with Duchenne or Becker muscular dystrophy.

A total of 278 families of probands with Duchenne or Becker muscular dystrophy has been ascertained and offered genetic counselling. Linkage studies have been performed in these families using polymorphic DNA markers identifying loci linked to Duchenne and Becker muscular dystrophy. The clinical features of the probands are discussed: there was marked intrafamilial resemblance in the severity of the disease. We estimate that a complete study of potential carriers in these families would require analysis of samples from approximately 1400 subjects. The results of linkage studies tended to move women's carrier risk estimates (based on CK and pedigree data) towards the extremes of the risk categories, providing a more definitive risk estimate for 81% of the women who were previously in the middle range of carrier risk probabilities. About 70% of the families had only one affected member. Linkage analysis altered carrier risk estimates in 95% of sisters and aunts of index cases, but only affected estimates of the mother's carrier risks in about 11% of isolated cases. Even where linkage studies were not helpful in elucidating carrier risks, information could usually be obtained for use in prenatal diagnosis if required. We have assessed the attitudes to pregnancy and prenatal diagnosis of women at risk of being carriers of Duchenne or Becker muscular dystrophy and report 17 pregnancies in these women.     

The InterLACE study: Design,data harmonization and characteristics across 20 studies on women’s health

ObjectivesThe International Collaboration for a Life Course Approach to Reproductive Health and Chronic Disease Events (InterLACE) project is a global research collaboration that aims to advance understanding of women’s reproductive health in relation to chronic disease risk by pooling individual participant data from several cohort and cross-sectional studies. The aim of this paper is to describe the characteristics of contributing studies and to present the distribution of demographic and reproductive factors and chronic disease outcomes in InterLACE.Study designInterLACE is an individual-level pooled study of 20 observational studies (12 of which are longitudinal) from ten countries. Variables were harmonized across studies to create a new and systematic synthesis of life-course data.Main outcome measuresHarmonized data were derived in three domains: 1) socio-demographic and lifestyle factors, 2) female reproductive characteristics, and 3) chronic disease outcomes (cardiovascular disease (CVD) and diabetes).ResultsInterLACE pooled data from 229,054 mid-aged women. Overall, 76% of the women were Caucasian and 22% Japanese; other ethnicities (of 300 or more participants) included Hispanic/Latin American (0.2%), Chinese (0.2%), Middle Eastern (0.3%), African/black (0.5%), and Other (1.0%). The median age at baseline was 47 years (Inter-quartile range (IQR): 41–53), and that at the last follow-up was 56 years (IQR: 48–64). Regarding reproductive characteristics, half of the women (49.8%) had their first menstruation (menarche) at 12–13 years of age. The distribution of menopausal status and the prevalence of chronic disease varied considerably among studies. At baseline, most women (57%) were pre- or peri-menopausal, 20% reported a natural menopause (range 0.8–55.6%) and the remainder had surgery or were taking hormones. By the end of follow-up, the prevalence rates of CVD and diabetes were 7.2% (range 0.9–24.6%) and 5.1% (range 1.3–13.2%), respectively.ConclusionsThe scale and heterogeneity of InterLACE data provide an opportunity to strengthen evidence concerning the relationships between reproductive health through life and subsequent risks of chronic disease, including cross-cultural comparisons.     

Hereditary hemorrhagic telangiectasia and risks for adverse pregnancy outcomes

Hereditary hemorrhagic telangiectasia (HHT) is an autosomal dominant vascular dysplasia characterized by epistaxis, mucocutaneous telangiectasias, and arteriovenous malformations (AVM) in the brain, lung, liver, gastrointestinal tract, or spine. While pregnant women with HHT are known to have increased risks due to pulmonary AVMs, little is known about any increased risk for fetal birth defects or other adverse pregnancy outcomes. To investigate potential increased risk, individuals with a clinical diagnosis of HHT were asked to complete a survey composed of four sections: demographics, personal history of HHT, personal history of birth defects (modeled after state registries), and reproductive history. A total of 226 participants reported outcomes of 560 pregnancies, as well as self-reported personal history of birth defects. Of the 560 pregnancies, 450 (80.4%) resulted in 457 live births and 63 (13.8%) were pre-term. Of the 110 pregnancy losses, 80 (72.7%) were first trimester and five were stillborn. Anomalies considered to be medically or cosmetically significant were reported in 17 babies (3.7%). The presence of significant anomalies was not significantly associated with whether the baby had an HHT diagnosis (P=0.55) or the gender of the parent with HHT (P=0.32). Four liveborn babies and one stillborn had a cerebral AVM or hemorrhage in the perinatal period. Prevalence of uterine hemorrhage, pre-eclampsia, placental abnormalities, low-birth weight, and infertility did not appear increased over the general population. These data provide some reassurance that HHT does not lead to an appreciable increased risk for birth defects or other adverse pregnancy outcomes.     

Depression during pregnancy: the potential impact of increased risk for fetal aneuploidy on maternal mood

Depression during pregnancy can have serious consequences for families. Indications of fetal aneuploidy can induce maternal stress, a risk factor for depression. Few studies have assessed symptoms of depression in pregnant women soon after they receive results indicating increased risk for fetal aneuploidy. We compared symptoms of depression in women who had increased risks for fetal aneuploidy with two other groups of pregnant women at similar gestational ages: controls, and women taking antidepressant medications (MEDS). Eighty-one women attending the British Columbia (BC) Medical Genetics (MG) Program regarding positive maternal serum screens or ultrasound soft marker findings completed the Edinburgh Postnatal Depression Scale (EPDS). Control ( n  = 41) and MEDS ( n  = 41) groups were recruited from the community or the BC Reproductive Mental Health program. A threshold score of 12 on the EPDS was used to calculate percentages of women likely to be depressed. Mean EPDS scores were compared using anova , followed by post-hoc tests. In the control, MG, and MEDS groups, 2.4%, 35%, and 52.4% of women, respectively, scored above 12. Mean EPDS score was significantly higher in the MG group than in the control group (p < 0.0001). These results suggest a place for depression screening in prenatal genetic counseling.     

Periconceptional intake of vitamin supplements and risk of multiple congenital anomalies

Numerous studies have reported reduced risks for a variety of single congenital anomaly phenotypes associated with maternal periconceptional use of vitamin supplements containing folic acid. Here we investigated whether periconceptional use of vitamin supplements containing folic acid by women altered their risk for delivering infants with multiple congenital anomalies (MCAs). Data were derived from a case-control study representing deliveries (fetal deaths and infants) from 2 California counties between January 1993 and July 1996. MCAs were defined as 2 or more congenital anomalies affecting more than one organ system or a major anomaly in combination with 2 minor anomalies. Controls were randomly selected from nonmalformed live-born infants. Telephone interviews were conducted with 112 (73.7% of eligible) case and 195 (78.0% of eligible) control mothers. Compared to women who did not use multivitamin supplements containing folic acid in the period 3 months before through 3 months after conception, women who used in this time period were observed to have an elevated risk to deliver fetuses or infants with MCAs, odds ratio = 2.6 (95% confidence interval 1.1-6.2). This elevated risk was not substantially altered (adjusted odds ratio = 2.9 [0.8-10.3]) by adjusting for maternal race/ethnicity, education, gravidity, body mass index, alcohol consumption, and cigarette smoking. No particular organ system seemed to be uniquely represented among the MCA fetuses and infants whose mothers used vitamin supplements. The observed elevated risk associated with maternal vitamin use is considered to be preliminary and needs to be replicated in other populations.     

DUCHEN: an interactive computer program for calculating heterozygosity (carrier) risks in X-linked recessive lethal diseases, and its application in Duchenne muscular dystrophy

The program DUCHEN calculates the probability that a woman is a carrier of an X-linked, lethal recessive disease on the basis of information in the woman's family and any available biochemical data. It is easily used by persons without computer knowledge or experience. The present version can accommodate families consisting of up to 100 people in seven generations. Risks may be estimated on the basis of pedigree information only, or with the inclusion of one or more types of biochemical test results. Biochemical data are incorporated with pedigree information into final risks using the powerful statistical technique of logistic discrimination, a procedure particularly suited for the separation of non-normal populations on the basis of overlapping quantitative characteristics. Mutation rates are specified separately for males and females. DUCHEN is available in FORTRAN 77, IBM BASIC, and Applesoft BASIC, and may be used on a variety of mainframe or microcomputers. The model was used to calculate risks for 375 girls and women in 46 families with Duchenne muscular dystrophy (DMD); serum creatine kinase tests had been carried out on 167 of these subjects who were of reproductive age. Carrier probabilities equal to or lower than the population risk (0.0004) were obtained for 21% of the aunts and 43% of the cousins of affected boys from families with an isolated case of DMD and for 14% of the cousins of affected boys from families with a known DMD history. DUCHEN should assist counsellors in determining which members of large families should be further examined using either standard biochemical carrier detection methods or DNA marker studies.(ABSTRACT TRUNCATED AT 250 WORDS)