Carl A. Huether

Sex ratios in fetuses and liveborn infants with autosomal aneuploidy

Ten data sources were used substantially to increase the available data for estimating fetal and livebirth sex ratios for Patau (trisomy 13), Edwards (trisomy 18), and Down (trisomy 21) syndromes and controls. The fetal sex ratio estimate was 0.88 (N = 584) for trisomy 13, 0.90 (N = 1702) for trisomy 18, and 1.16 (N = 3154) for trisomy 21. All were significantly different from prenatal controls (1.07). The estimated ratios in prenatal controls were 1.28 (N = 1409) for CVSs and 1.06 (N = 49427) for amniocenteses, indicating a clear differential selection against males, mostly during the first half of fetal development. By contrast, there were no sex ratio differences for any of the trisomies when comparing gestational ages < 16 and > 16 weeks. The livebirth sex ratio estimate was 0.90 (N = 293) for trisomy 13, 0.63 (N = 497) for trisomy 18, and 1.15 (N = 6424) for trisomy 21, the latter two being statistically different than controls (1.05) (N = 3660707). These ratios for trisomies 13 and 18 were also statistically different than the ratio for trisomy 21. Only in trisomy 18 did the sex ratios in fetuses and livebirths differ, indicating a prenatal selection against males > 16 weeks. No effects of maternal age or race were found on these estimates for any of the fetal or livebirth trisomies. Sex ratios for translocations and mosaics were also estimated for these aneuploids. Compared to previous estimates, these results are less extreme, most likely because of larger sample sizes and less sample bias. They support the hypothesis that these trisomy sex ratios are skewed at conception, or become so during embryonic development through differential intrauterine selection. The estimate for Down syndrome livebirths is also consistent with the hypothesis that its higher sex ratio is associated with paternal nondisjunction.

Genetic Literacy of Undergraduate Non–Science Majors and the Impact of Introductory Biology and Genetics Courses

ABSTRACT With the advancement of genetic information and technologies, there is an increasing need for a genetically literate public. This study looks critically at student learning and at the current instruction of genetics in introductory non–science major biology and genetics courses at the undergraduate level. A new diagnostic tool, the Genetic Literacy Assessment Instrument, was administered pre- and postcourse to more than 300 students in six introductory nonmajor courses that emphasize genetics to varying degrees. Current data from students in these courses show a precourse average score of 43 percent correct zn the inventory. Postcourse scores increased only modestly, to an average of 49 percent. In this article, we discuss the impact of teaching methods and course content on scores, as well as student learning in the different content areas of genetics. The results suggest that further studies in genetics education are needed to better understand the effect of teaching methods on achieving genetic literacy.

Genetics Content in Introductory Biology Courses for Non-Science Majors: Theory and Practice

lives requires greater attention to the study of genetics in our educational system. To understand the significance of the rough draft of the human genome, the related benefits and risks of gene therapy, and the increasing complexity of gene–gene and gene–environment interactions, the public must understand basic principles of genetics, including human genetics.The National Science Education Standards, developed by the National Research Council, recommend that the concept of inheritance be introduced in grades kindergarten (K)–4 and the basic principles of heredity and genes in grades 5–8. The standards for grades 9–12 concentrate on the molecular basis of inheritance, including DNA structure and function, genetic change, and variation (NRC 1996). No similar benchmarks exist for the genetics and human genetics curricula offered at collegiate institutions. Medical schools have received more attention in this regard than have college and university undergraduate courses. Twenty years ago, a noteworthy study of 103 of the 107 medical schools then operating in the United States analyzed the medical genetics courses in terms of content, duration, responsible department, and primary discipline of the instructor (Childs et al. 1981). The authors concluded that human genetics had not found a comfortable niche in medical schools. Shortly thereafter, Goodman (1982) suggested implementation of a core curriculum in genetics and clinical genetics and further proposed establishment of a Genetics Education Task Group to coordinate the process. Much later, in 1995, the Information and Education (I&E) Committee of the American Society of Human Genetics (ASHG) submitted a report outlining a core curriculum in medical genetics for medical school (Friedman et al. 1995). Studies conducted at the precollege level and in medical schools left the undergraduate years unaddressed. In 1999, ASHG began to address this deficiency by offering a workshop on undergraduate genetics education at its annual meeting (Bender et al. 1999). Catalyzed in part by the positive reception of this workshop, the I&E Committee appointed a subcommittee on undergraduate genetics education to develop a set of content recommendations for institutions of higher education (Paula Gregory, ASHG I&E chairperson, personal communication, 1999). The committee, which comprises the first eight authors of this article, represents a wide variety of educational and professional backgrounds, including undergraduate biology education, clinical genetics, nursing, genetics education, and more than 100 years of cumulative teaching experience.

A Clinical Study of Vasectomy Failure and Recanalization

An analysis was made of the 26 unsuccessful operations from the 2,197 vasectomies performed in a non-profit medical facility. Hhe operations were performed by 6 physicians and significant differences were found in the failure rates. In all instances the tissue removed proved to be vas deferens when examined histologically. Two factors seem to account for the differences of failure rates amoung the physicians; 1) the lenght of vas excised and 2) the character of thechnique. Phsicians with a high rate of success removed a significantly longer section of vas than physicians exhibiting higher failure rates. At least 15 mm. of vas should be excised to maximize the success of the procedure. Excised vas segments less than 15 mm. had up to a 25-fold greater incidence of failure. Although considered of secondary importance, good surgical technique subjectively measured by the minimal amount of accessory tissue attached to the excised vasa was also considered to aid in reducing the number of vasectomy failures.

Impact of prenatal diagnosis on revised livebirth prevalence estimates of Down syndrome in the Lothian region of Scotland, 1978-1992

Ramsay et al. [(1991) Biomed Pharmacother 45:267–272] reported on the livebirth prevalence of Down syndrome in the Lothian region of Scotland during 1978–1989. Their results suggested a temporal association between the events of Chernobyl in April 1986 and a significant excess of cases in 1987. In the current study the data were extended for 3 years and reanalyzed, a major objective being to correct for the differential loss of fetuses with Down syndrome which occurs between prenatal diagnosis and birth. Other objectives were to estimate the prevalence reduction due to prenatal diagnosis, quinquennial maternal age‐specific risk rates, and the level of ascertainment of cases. The reanalysis found a 12‐year prevalence rate of 1.29 vs. the previous rate of 1.34, and a shift of the annual prevalence peak to 1988, with a reduced prevalence in 1987 compared to that found in the earlier study. The new results are less consistent in showing an association of Down syndrome clustering with the Chernobyl accident. For the 15‐year study period, a 23% overall reduction in prevalence occurred due to prenatal diagnosis and elective abortion of affected fetuses, with a 50% reduction to women ≥35 years of age. For 1988–1992, these reductions were 33% and 60%, which are among the highest reported in the literature for these time periods. The estimated quinquennial maternal risk rates were very similar to others already reported, and the data are consistent with a high level of case ascertainment. Since these women are approaching the upper limits of fetal detection through advanced maternal age alone, continued reduction in prevalence rates for Down syndrome through prenatal diagnosis and elective abortion will come mostly from increased use of other (chemical) screening techniques now available.

Causes of low utilization of amniocentesis by women of advanced maternal age

Abstract The objectives of this study were to determine current usage of amniocentesis by women of advanced maternal age in a southwestern Ohio county and to determine potential usage levels by surveying women not utilizing the procedure to understand their reasons. For women age 35 and older giving birth in Hamilton County, Ohio, the estimated percentage using amniocentesis was 3.9 in 1978, 7.6 in 1979, and 13.3 in 1980. Approximately comparable statewide utilization rates were 7.0, 11.5, and 17.2 respectively. A telephone survey during the summer of 1980 of 81 Hamilton County women age 35 and older recently giving birth to a normal baby found four main reasons why they did not utilize amniocentesis: (1) they did not feel at an increased risk (29.6 per cent); (2) they had never heard of the test (24.7 per cent); (3) they were opposed to abortion (21.0 per cent); and (4) no one suggested they have the test done (19.8 per cent). Their physicians reported that 81 per cent of these women had received prenata...

Career Research Interests and Training of Genetic Counseling Students

Research is important to validate clinical services, provide information on the effectiveness of practice techniques, and develop the knowledge base of a clinical profession. Genetic counseling students from American Board of Genetic Counseling (ABGC) accredited training programs were surveyed to determine their career research interests and interest in pursuing a hypothetical doctoral degree in genetic counseling. Genetic counseling program directors were surveyed to assess the emphasis on research training within their programs. A substantial number (46%, n = 92) of genetic counseling students are interested in performing research in their careers and many (40%, n = 80) would pursue a doctoral degree in genetic counseling if it was available. Students and directors from programs with a thesis requirement reported a significantly higher emphasis on career research preparation than those from programs without a thesis requirement. The results of this study indicate that future genetic counselors are interested in contributing to the research base that will advance the field. This study suggests a need to strengthen research training within ABGC accredited graduate programs and explore the development of a doctoral degree option in genetic counseling.

The Impact of Test Outcome Certainty on Interest in Genetic Testing Among College Women.

Osteoporosis and hemochromatosis are both late-onset preventable diseases, but future genetic tests for these conditions are likely to differ in their predictive abilities. To determine whether interest in a specific genetic test for hemochromatosis would be higher than interest in a theoretical test for osteoporosis susceptibility, undergraduate women at the University of Cincinnati (N = 181) were surveyed regarding their interest in genetic testing for these conditions. The clinical features of the diseases and the limits of a genetic test for each were described. Sixty-three percent of the total population was interested in genetic testing with a trend toward higher interest in the osteoporosis group. Disease familiarity, perceived disease severity, and perceived risk for disease appear to be more important predictors of genetic test acceptance than diagnostic specificity. Suggested implications for the development of population genetic screening tests are discussed.

Characterization of the Practice and Attitudes of Genetic Counselors with Doctoral Degrees

Potential advantages and disadvantages of doctoral training in genetic counseling have been debated. In this study, individual interviews were conducted to characterize the practice and attitudes of genetic counselors who have achieved doctoral degrees in any field. Participants (N=31) were more likely to spend time in research and less likely to spend time in clinic than genetic counselors in general. Advantages identified by participants were consistent with theorized advantages, and included increased knowledge, wider research roles, additional opportunities and greater respect. Disadvantages identified by participants focused more on individual perspectives than previously theorized profession-wide disadvantages. These included increased time commitment and decreased patient contact. The attitudes of participants towards the development of doctoral training in genetic counseling were generally positive. The results suggest that doctoral training in genetic counseling would have more benefits than drawbacks for individuals pursuing this degree.

Epidemiologic Aspects of Down Syndrome

A recent study of more than one million consecutive live births in British Columbia found that 53/1000 had diseases with an important genetic component before approximately 25 years of age (Baird et al., 1988). Down syndrome was only 2.3% of this total (1.22/1000), but studies of severe mental retardation in children over 1 year of age in two Swedish counties found 33% had Down syndrome, out of a prevalence of severe mental retardation at 1 to 16 years of age of 3.5/1000 (Gustavson et al., 1977a,b). Additionally, the prevalence rate of retardation dropped 42% from 1959–1962 to 1967–1970 in these studies, mainly as a result of a 54% decline in births with Down syndrome. More recent reports (Hook, 1983a; Kiely, 1987) supported these results. Baird and Sadovnick (1988a) also showed that the probability of survival of live births with Down syndrome has continued to increase, and that currently 44% survive to age 60. These studies reinforce the substantial contribution births with Down syndrome make to the problem of human health, and the positive result to be obtained from their prevention.