A systematic investigation into the etiology of congenital heart diseases (CHD) has been undertaken through the testing of four alternative hypotheses. Data was obtained for six common congenital heart lesions from the investigation of familial aggregates, twin studies, and chromosomal evaluations. Animal homologies were also considered in the evaluation of the hypotheses. Hypothesis 1—no genetic basis for the etiology of congenital heart diseases—was tested and rejected. Then in an effort to define the possible genetic basis of congenital cardiovascular malformations hypothesis 2—the genetic basis of CHD is determined by gross chromosomal aberrations—was evaluated by reviewing karyotypes of nonsyndrome CHD patients in the literature as as well as 104 personal cases. Rejection of hypothesis 2 is required by all available evidence. Hypothesis 3—the genetic basis of common isolated congenital heart lesions is determined by single mutant genes—was also tested and rejected. Hypothesis 4—congenital heart diseases are a heterogeneous category of developmental anomalies, representing in most cases the multifactorial inheritance of threshold characters, the expression of which is the product of a genetic-environmental interaction—was tested by the same criteria. On the basis of these criteria this hypothesis could not be rejected. Therefore the multifactorial hypothesis is proposed as a working hypothesis which encompasses both the genetic and environmental factors known to participate in the etiology of congenital heart diseases. It is hoped that through the testing of this hypothesis investigation into new areas will be stimulated, which ultimately will lead to active methods of prevention.

SUMMARY A genetic-epidemiologic study was undertaken of a white Colorado population of 207 patients who had a myocardial infarction before age 55 years. Nineteen independent variables were compared between the 207 cases and 621 controls, matched 3:1. The highest risk ratios were associated with a positive family history for ischemic heart disease (IHD). The heritability of IHD was 63% when families with the monogenic forms of hyperlipoproteinemia were included, and 56% when they were excluded. A risk index was developed that incorporates family history into a data base of risk factors, which can be readily assessed by the clinician obtaining a screening history, physical and standard laboratory tests. A scale of 0-10 was devised and the predictive value of the index was tested against another data set. The efficiency of the index was maximal at a screening level of 5. This study suggests that it is logistically feasible to seek patients at high risk for intensive management in a clinical setting (high-risk strategy) using risk indices similar to the one developed for this study, which emphasize the very important familial component to IHD. determinant for entry. The intake period for this study began in January 1976.A control group of 621 subjects was matched 3:1 with the patients for age, sex and race. These subjects were drawn from over 3000 subjects who were selfreferred to two community-wide heart disease screening programs in which our group participates. On the basis of the screening evaluation, all control subjects were judged to be free of IHD before and at the time of intake.All subjects completed a questionnaire and were examined according to a protocol that obtained height (without shoes), weight (in indoor clothing), blood pressure and fasting cholesterol and triglycerides. Certain data were obtained in one group and not the other. Information on juvenile diabetes and hypertension in first-degree relatives and IHD in second-degree relatives was called for in the protocols of patients with infarcts, but only in the protocol of one of the screening programs. Therefore, these three factors were compared in a subset of only 140 patients matched 1:1 with controls of the same age, sex and race.Lipid and lipoprotein determinations were performed in our laboratory by the methods outlined for the Lipid Research Clinics Program.' Blood pressures were taken according to the protocol of the Pooling Project Research Group,2 except that diastolic pressure was taken as the abrupt muffling of sound (phase IV). The threshold for diagnosis of hypertension in a patient or first-degree relative was 140/90 mm Hg. Only first-degree relatives 12 years and older were included in the family study because a blood pressure of this level is not found as a ninety-fifth percentile discriminant until this age. Relative weight was determined according to published standards of the Metropolitan Life Insurance Company.The self-administered questionnaires were designed to cover a priori risk factors that have been implicated in IHD in...

Recent genetic, cytogenetic, and clinical findings of the Ullrich-Noonan syndrome have been reviewed in the context of a personal series of 81 patients, the majority of whom were found in 23 families. Direct transmission of all familial cases strongly supports the proposed autosomal dominant mode of inheritance. Cytogenetic evaluation, including utilization of Q and G banding techniques, has failed to disclose a chromosomal anomaly. Diagnostic criteria, frequency of anomalies, and disabilities are presented together with cardiovascular abnormalities and recurrence risks.The Ullrich-Noonan syndrome (Turner phenotype) is thought to be one of the most common syn¬ dromes transmitted by a Mendelian mode. But at the same time, it is a syndrome surrounded by a certain amount of confusion. The confusion ranges from relatively unimportant things, as what to name this disorder,

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