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L B Jorde

Publications and source records attributed to L B Jorde.

At least 91 records · Page 5Linked to original sources
PubMed1989

The UCLA-University of Utah epidemiologic survey of autism: recurrence risk estimates and genetic counseling.

The authors recently reported, in this journal, an epidemiologic survey of autism in Utah. Twenty (9.7%) of the 207 families ascertained had more than one autistic child. Analyses of these data revealed that autism is 215 times more frequent among the siblings of autistic patients than in the general population. The overall recurrence risk estimate (the chance that each sibling born after an autistic child will develop autism) is 8.6%. If the first autistic child is a male the recurrence risk estimate is 7%, and if a female 14.5%. These new recurrence risk estimates should be made available to all individuals who have autistic children and are interested in family planning.

Autistic Disorder↗
PubMed1988

Relation between family history of coronary artery disease and coronary risk variables.

The relation between family history of coronary artery disease (CAD) and coronary risk variables was examined in 1,058 Utah adults. Subjects were divided into 3 family history score groups (low, intermediate and high) and the effects of 60 potential risk variables were assessed using multiple stepwise discriminant analysis. After controlling for age effects, the variables entering the discriminant function equation (p less than 0.01) were cholesterol, years smoking cigarettes, high-density lipoprotein cholesterol and triceps skinfold thickness. Although normal blood pressure variation did not discriminate among family history groups, those with a positive family history of CAD were more likely to develop hypertension than those without a family history (age-adjusted relative risk 1.79, with 95% confidence limits 1.03 and 3.09). In spite of significant differences among family history score groups with regard to risk variables, the discriminant analysis classified only 39% of subjects into the correct group. It was concluded that other unknown risk variables must mediate the effects of family history of CAD. Thus, family history should be considered an independent risk factor for CAD.

Adult↗
PubMed1988

Inbreeding and genetic disease in Sottunga, Finland.

The contribution of inbreeding to the prevalence of recessive genetic diseases in the Aland Island parish of Sottunga is investigated. Genealogical data for 3,030 individuals spanning up to 15 generations were used to estimate inbreeding. This small island community shows a low average inbreeding value of .0031 for the period 1725-1975. A cohort analysis shows that inbreeding increased from 1750 to 1900, when maximum inbreeding for those born in Sottunga reached .0057. A sharp decline in inbreeding occurred thereafter. Individuals with island-born parents made the largest contributions to inbreeding in all time periods compared to those with one or two migrant parents. These trends are consistent with changing migration patterns and isolate breakdown in Aland since 1900. An analysis of pedigree development demonstrates that remote consanguinity contributed more to inbreeding through time than close consanguinity. Both the number of common ancestors and the number of paths of relationship between spouses increased dramatically through time, the latter at a much faster rate. The contribution to average inbreeding per path, however, diminished rapidly through time. This analysis indicates that inbreeding does not account for the high incidence of autosomal recessive disorders, such as tapetoretinal disease, found in the parish.

Consanguinity↗
PubMed1988

Genetic structure of the Saguenay, 1852-1911: evidence from migration and isonymy matrices.

The Saguenay is a region in northeastern Québec populated in the second half of the 19th century through migration from other parts of Québec. The present-day population of nearly 300,000 is the result of both immigration and high rates of intrinsic growth. This population has been of interest to geneticists because of the high incidence of certain hereditary diseases, notably spastic ataxia, tyrosinemia, agenesis of the corpus callosum, vitamin D-dependent rickets, and myotonic dystrophy. Parent-offspring migration and isonymy matrices were used to estimate random kinship using the Malécot model for six 10-year time periods from 1852-1911. Comparisons between two estimates of kinship--one from parent-offspring migration matrices (phi) and the other from isonymy (R)--and geographic distance were made using both product-moment and Mantel correlation. Comparisons of within- and between-subdivision kinship were made using nonparametric and Mantel correlation. Within-subdivision kinship from the phi matrix was also compared with kinship estimated from marriage dispensations for endogamous marriages. The estimates of random kinship from the parent-offspring matrices showed a good fit with geography. However, isonymy did not correlate well with geographic distance; and phi and R showed no correlation until the last two time periods, and the diagonal of phi did not correlate with the marriage dispensations. Examination of scatterplots of phi vs. R suggests that nonrandom migration during the process of settlement formation is responsible for the lack of correlation. While movement across space seems to be highly dependent on distance, nonrandom selection of migrants means that between-subdivision estimates of kinship based on migration are not congruent with those obtained by other methods. On the whole, genetic differentiation seems to have been low due to the high levels of movement between subdivisions and immigration. The weak dependence of genetic structure on geographic distances in the present population is demonstrated by mapping the geographic distribution of cases of three recessively inherited diseases.

Emigration and Immigration↗
PubMed1988

Founder effect and genetic disease in Sottunga, Finland.

Pedigree data are analyzed in order to determine the factors responsible for the high frequencies of certain genetic disorders in an isolated Swedish-speaking population of Finland's A land archipelago. The founders of Sottunga are identified, and the genetic contributions of each founder to descending birth cohorts are estimated. Founders born before 1700 have far more descendants in the contemporary gene pool than do more recent founders. However, because of migration and depopulation since 1900, the expected genetic contributions of the early founders to the present-day population are similar to those of later founders. A descendant in the contemporary population has a 2% chance of having inherited a particular gene from the founder who makes the largest single contribution to the gene pool. This corresponds approximately to a 2% probability of inheriting an autosomal dominant disease gene from this founder. Given an average inbreeding coefficient of 0.0016, the probability of inheriting two recessive disease genes from this founder is 0.000032. The incidence of autosomal dominant von Willebrand disease in Sottunga is greater than 10% while that of autosomal recessive tapetoretinal disease is 1.5%. We conclude, therefore, that the high frequencies of these diseases are not due to the disproportionate genetic contribution of one or a few particular founders. It is more likely that these disease genes occurred in high frequency in the initial population or were introduced repeatedly through time.

Finland↗
PubMed1988

Twinning rate in Scandinavia, Germany and The Netherlands during years of privation.

Twinning rates were studied in Swedes, Aland Islanders, Finns, Germans, and Dutch during years of starvation when death rates were two to three times higher than average. In contrast to the situation among some animals, this study suggests that nutrition above a certain threshold is unimportant for human reproduction, including twinning. The twinning rates for these different populations display marked temporal differences, but low values in the twinning rate are not consistently associated with periods of epidemics, famine, or similar nutritional stress. After years of privation and/or separation of spouses, a rapid "catch-up effect" can often be seen in the twinning rates, as well as marriage and birth rates. Psychoendocrine factors and interparental immunological conditions that may be involved in this phenomenon are discussed.

Female↗
PubMed1988

A test of the heterozygote-advantage hypothesis in cystic fibrosis carriers.

We report a test of the hypothesis that the high frequency of cystic fibrosis (CF) in Caucasian populations is due to a fertility advantage in CF carriers. One hundred forty-three grandparent couples of Utah CF cases were compared with 20 replicate sets of matched control couples drawn from the Utah Genealogical Database. Ascertainment correction, which has not been applied in previous studies of CF carrier fertility, was applied to these data. Before ascertainment correction was applied, CF carriers appeared to manifest a significant fertility advantage over controls. After the correction formula was applied, this difference disappeared. Carriers and controls were also compared in terms of the length of intervals between births. Again, no significant differences were found. It was concluded that fertility differences are unlikely to account for the observed Caucasian CF gene frequency. Other mechanisms, particularly a past selective event or random genetic drift, are more likely to be responsible.

Birth Rate↗
PubMed1987

Genetic structure of the Utah Mormons: isonymy analysis.

Isonymy analysis is reported for a sample of 188,895 marriages extracted from the Utah Genealogical Database. Inbreeding rates estimated by isonymy are low, ranging from 0.005 for the earliest marriage cohort (1800-1809) to 0.0008 in the most recent cohort (1950-1959). The inbreeding values decrease considerably through time, but they are consistently higher than inbreeding values estimated from pedigrees. Several explanations are offered for this, including polyphyletism of surnames and the presence of Scandinavian patronyms in this population. Random isonymy between subdivisions is also compared with random kinship estimated from migration matrices. In terms of within-subdivision kinship, the two approaches yield similar results. However, the results are quite dissimilar for between-subdivision kinship. This reflects the recent and nonrandom settlement of Utah by different ethnic groups with different surname distributions. In later time periods, the correlations between the two types of kinship estimates increase, showing that migration patterns (which are strongly determined by geographic distance) exert an increasing influence on the distribution of surnames. Logistic regression is performed on a subset of marriages (n = 88,202), using isonymous vs. nonisonymous marriage as the dependent variable. The independent variables are year of marriage, geographic distance between husband's and wife's birthplaces, endogamous vs. exogamous marriage, and population sizes of husband's and wife's birthplaces. Year of marriage and geographic distance are shown to be significant independent predictors of isonymous marriage.

Christianity↗
PubMed1987

The effect of non-random migration on genetic differences between populations.

Models of genetic population structure generally assume that emigrants from each local group are drawn at random from the set of individuals born there. We show that small violations of this assumption can have disproportionately large effects on genetic population structure, and we introduce a statistical method for measuring this effect.

Finland↗
PubMed1986

Factor analysis suggesting contrasting determinants for different blood pressure measurements.

A multiple regression analysis was performed on statistically independent factors derived from blood pressure measurements and possible predictive variables in 618 Utah adults. Nine blood pressure factors obtained in a previous study composed the dependent variables; 35 anthropometric, questionnaire, and biochemical variables were reduced by factor analysis to 10 factors and used as independent variables. Body size and obesity had significant independent effects on different types of blood pressure: body size correlated most highly with systolic blood pressure, while obesity correlated most highly with sitting diastolic blood pressure measurements. Smoking did not correlate with sitting blood pressure but did show a significant positive correlation (after controlling for obesity) with tilt and supine diastolic pressure. Alcohol consumption correlated positively with sitting diastolic pressure when the effects of body size and obesity were controlled. No correlations were found between urinary potassium or sodium excretion and any blood pressure factors, but a significant positive correlation was seen between plasma sodium concentration and several different types of diastolic blood pressure measurements. Psychological stress showed a significant independent positive correlation with systolic blood pressure measurements that was strongest in adults over 35 years of age. The multiple correlation values for the multiple regression equations ranged from 0.19 to 0.52.

Adolescent↗
PubMed1986

Innovative blood pressure measurements yield information not reflected by sitting measurements.

A study of 873 healthy adults and children from Utah kindreds was performed to identify redundant and unique information contained in multiple diverse blood pressure determinations. Systolic blood pressure, fourth-phase and fifth-phase diastolic blood pressures, and simultaneous heart rates were measured in subjects sitting, standing, supine, and tilting, during half-maximal handgrip exercise, and just before blood drawing. A correlation matrix of 57 blood pressure and pulse variables in 618 healthy adults was analyzed. Factor analysis of the correlation matrix showed that all systolic blood pressures loaded as a single factor, accounting for 44% of the total variance of the observed variables. All heart rates also loaded together as a single factor. Diastolic blood pressures showed much more heterogeneity of information distributed among five separate factors. The same basic factors were found in young adults (age, 18-35 years) and older adults (age, 36 + years). Children under 12 years of age showed very different factor patterns, and youths 12 to 17 years of age showed patterns intermediate between those of adults and children. In light of recent clinical trials, better definitions are being sought for hypertension. Information from blood pressures other than sitting determinations may improve the definition of hypertension or better predict which patients have the highest risk of hypertension and its cardiovascular complications.

Adolescent↗
PubMed1986

Linkage disequilibria between pairs of loci within a highly polymorphic region of chromosome 2Q.

A recently described region on chromosome 2q contains seven restriction fragment length polymorphisms (RFLPs) revealed by single-copy probes isolated from a 20-kilobase (kb) segment of a single cosmid insert. Analysis of six of these loci demonstrates modest amounts of linkage disequilibrium. This reflects the presence of a substantial number of different haplotypes in this chromosome region and indicates that the region could be used as one highly polymorphic locus. No consistent relationship is found between the amount of linkage disequilibrium and the physical distance between pairs of loci. For seven of the 10 pairs of diallelic loci studied, the observed disequilibrium can be attributed primarily to the absence of the minor haplotype from the population. These results suggest that, for small regions of the genome, factors such as mutation, genetic drift, and population admixture may have effects that outweight those of recombination. In addition, results are reviewed which show that estimates of linkage disequilibrium coefficients for tightly linked loci are very imprecise. Thus, the inference of gene order from linkage disequilibrium values must be regarded with caution.

Alleles↗
PubMed1984

Population structure in the Connecticut Valley. I. Marital migration.

This study reports on an analysis of marital migration among 12 communities in the Connecticut River Valley of Massachusetts during the years 1790-1849. Genetic inferences are drawn, and the requisite assumptions considered. The effect of geographic distance on genetic kinship is predicted using Malécot's isolation-by-distance model. The resulting estimates are discussed in terms of geographic and historical factors. The configuration of communities as predicted by kinship values approximates closely their actual geographic locations. Estimated genetic heterogeneity was low for the historical Connecticut Valley population, and community isolation breaks down rapidly over time. The region thus assumes its place among a number of sedentary, agricultural populations for which the isolation-by-distance model provides an adequate representation. A regression analysis which includes variables in addition to distance indicates that historical and economic factors contribute some additional explanatory power to the distribution of mating frequencies.

Demography↗
PubMed1984

The inheritance of high density lipoprotein cholesterol and apolipoproteins A-I and A-II.

A large pedigree was ascertained through cases of early myocardial infarction. High density lipoprotein cholesterol and apolipoproteins A-I and A-II were measured on family members. Likelihood analysis, using the polygenic/major gene mixed model, provided no evidence that major loci play a role in determining the levels of any of the three measurements. Heritability estimates, assuming polygenic inheritance, were 0.59 and 0.26 for HDL-C level and A-II level, respectively. No evidence of genetic transmission of A-I level was found.

Adult↗
PubMed1984

Epidemiology of neural tube defects in Utah, 1940-1979.

The prevalence and distribution of 991 cases of neural tube defects who were born in Utah in 1940-1979 are analyzed. The average prevalence at birth is 1.00 per 1000 births (live and stillbirths), which is similar to other states in the western United States. A decline in prevalence is observed during the past 10 years, although there is not a long-term secular trend for the whole time period. Examination of hospital records shows that 17.9% of neural tube defects were not reported on birth or fetal death certificates. The male/female sex ratio is 0.67. No seasonality is found for spina bifida cases; however, a bimodal distribution, with a substantial deficit in May, is observed for anencephaly. A significant negative correlation is found between neural tube defect prevalence and the percentage of individuals in each Utah county who are members of the Mormon Church. No association is found between levels of fallout exposure in Utah and regional variation in neural tube defects, and time-space clustering analysis demonstrates no significant clusters of neural tube defects in Utah.

Anencephaly↗
PubMed1984

[Not Available].

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Demography↗