Diagnosis of sickle cell disease in chronically transfused patients.

Standard electrophoretic methods for the diagnosis of hemoglobinopathies are confounded in individuals chronically transfused. We present the accurate diagnosis of sickle cell disease in two such transfused patients by the application of polymerase chain reaction technology to analyze patient's hemoglobin beta-chain genes directly.

Genetic analysis of HLA in the U.S. Schmiedenleut Hutterites.

The Hutterites are an Anabaptist population, highly inbred, with large family sizes and extensively documented pedigrees. As part of genetic-epidemiologic studies of the impact of HLA on fertility, HLA-A, -B, -C, -DR, and -DQ typing was performed on a total of 650 Schmiedenleut Hutterities in South Dakota. An extraordinary degree of homogeneity was found. HLA-A1, -A2, -A3, -A24, and -A26 accounted for 83%, HLA-B8, -B27, -B35, -B51, -Bw60, and -Bw62 for 75%, and HLA-DR1, -DR2, -DR3, and -DR4 for 66% of the antigens at the respective HLA-A, -B, and -DR loci. All Hutterites characterized for HLA were descendants of no more than 78 ancestors. However, family analysis identified only 45 unique HLA haplotypes thought to reflect the original gene pool. Eight haplotypes were particularly frequent, accounting for nearly 50% of all observed haplotypes; four of these were consistent with a European ancestry. Coefficients measuring linkage disequilibrium were computed from haplotypes identified by family analysis. Overall, HLA analysis portrayed the Schmiedenleut Hutterities as a homogeneous and unique population, with disequilibrium among particular alleles and a spectrum of common and uncommon European haplotypes.

Low fetal loss rates after ultrasound-proved viability in early pregnancy.

Once pregnancy is recognized clinically, it is accepted that 12% to 15% undergo spontaneous abortion. However, the actual time of fetal demise has not yet been determined. To address this question, the outcomes of pregnancies identified before 21 days of conception by serum beta-human chorionic gonadotropin assays were studied. All subjects underwent ultrasound examinations at eight and 12 weeks' gestation. Among 220 women who had a viable pregnancy at eight weeks, only seven (3.2%) experienced a fetal loss thereafter. The results of this study suggest that most clinically recognized spontaneous abortions manifested after eight weeks actually represent pregnancies in which fetal demise occurred before eight weeks. These findings have important implications with respect to the safety of chorionic villi sampling and to the identification of exogenous agents that cause fetal wastage.

Adverse effects of human leukocyte antigen-DR sharing on fertility: a cohort study in a human isolate.

To elucidate further the reproductive effects of human leukocyte antigen (HLA) sharing among spouses, we have been investigating prospectively the relationship between HLA-A, -B, and -DR sharing and reproductive outcome in the Hutterites, a religious isolate that proscribes contraception. For the first time the reproductive effects of HLA-DR sharing in a fertile population is reported in this article. Median intervals from marriage to first through fifth births were longer among couples who shared more than one HLA-A, -B, or -DR antigen. Longer intervals were associated with increased spontaneous abortion rates among couples who shared HLA-DR antigens (27%), compared with couples who shared only HLA-A or -B antigens (9%) and couples who shared no antigens (12%). Median completed family sizes were 5.0, 8.5, and 8.0 among the groups, respectively. However, some couples who shared HLA-DR antigens experienced no spontaneous abortions, despite ten or more pregnancies. Therefore, although HLA-DR compatibility, per se, is not deleterious, our data suggest a potentially important role for undefined HLA-linked genes in normal pregnancy.

Shared HLA antigens and reproductive performance among Hutterites.

Shared histocompatibility antigens between spouses may affect reproductive outcome adversely as a result of prenatal selection against compatible fetuses. Evidence from both animal and human studies suggest that histocompatible fetuses may not initiate a maternal immunologic response that prevents rejection of the embryo. Therefore, parents sharing HLA antigens may produce compatible fetuses and consequently experience a greater frequency of early fetal losses and show poorer reproductive outcome than couples not sharing antigens. In the Hutterites, an inbred human isolate that proscribes contraception, we tested the hypothesis that couples sharing HLA antigens have poorer reproductive outcomes than couples who do not. The Hutterites are characterized by high fertility and large family sizes. Couples that share zero (no. = 21), one (no. = 15), and more than one (no. = 10) HLA-A or HLA-B antigens were compared for reproductive performance. Median intervals between births were larger among couples that share more than one antigen in eight of 11 intervals examined. In addition, the median intervals from marriage to first, fifth, and tenth birth were consistently larger among couples that share more than one antigen. Differences among the groups appear to become larger with increasing parity, suggesting that the effect of histocompatibility on reproductive performance becomes more evident in later pregnancies. These differences in reproductive performance between couples that share zero, one, or more than one HLA-A or HLA-B antigens may have significant evolutionary consequences. However, our results demonstrate that sharing HLA antigens does not preclude normal pregnancy and caution should be exercised before concluding that shared HLA antigens are solely responsible for repeated fetal losses.

Models for lineal effects in rhesus group fissions.

Gene distributions in daughter groups produced by three rhesus monkey group fissions are analyzed. Data employed are for the Tf, 6PGD, and CA II electrophoretic marker systems in the fissions producing new daughter groups F and M, F and O, and J and N in the Cayo Santiago rhesus colony. Wide variations in FST values were observed among the different markers in the various fissions. Overall, the observed FST values exceeded predictions of simple random fissioning models. However, on average, observations on electrophoretic markers fitted well with predicted values from lineal fissioning models. One of these lineal fissioning models, a simulation, incorporated the propagation of alleles in the matrilines of the fissioning groups. The second, an algebraic expression, utilized group sizes and average kinship values as parameters.

Malformations in infants of diabetic mothers: problems in study design.

Infants of diabetic mothers have a two- to threefold increased risk of having congenital malformations. Primary prevention of these malformations may be possible if the teratogenic mechanisms in diabetes can be identified. The Diabetes in Early Pregnancy Study (DIEP) addresses the questions of high malformation rates and fetal losses using an innovative study design. Women are recruited prior to pregnancy, monitored to ensure prompt diagnosis of pregnancy, and followed carefully for diabetic problems or fetal losses. To date, 450 diabetic and 550 normal control prepregnant women have been recruited. A basal body temperature monitoring system has been successful in identifying pregnant women within 21 days of conception. Before initiating such a study, problems of feasibility, study design, and possible bias had to be solved. This report summarizes our experience in designing and conducting a prospective pregnancy study. The DIEP demonstrates that a truly prospective pregnancy study is feasible.