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B K Suarez

Publications and source records attributed to B K Suarez.

At least 55 records · Page 3Linked to original sources
PubMed1985

Genetic variation in North Amerindian populations: association with sociocultural complexity.

A survey of nine polymorphic loci for 82 North Amerindian populations was undertaken to test the hypothesis that increasing levels of sociocultural complexity are ineluctably accompanied by increased heterozygosity. The data reveal a significant relationship in the predicted direction. Moreover, the significant correlation between average heterozygosity and sociocultural complexity is substantially increased by the removal of 19 highly admixed samples. However, this relationship, at least among North Amerindian populations, may be more apparent than real since both mean heterozygosity and the level of sociocultural organization are significantly negatively correlated with latitude. When this latter variable is controlled for, all correlations between heterozygosity and sociocultural complexity are rendered nonsignificant.

Cultural Characteristics↗
PubMed1985

Genetic variation in North Amerindian populations: covariance with climate.

Allelic frequencies at seven polymorphic loci in 74 North Amerindian populations are examined relative to patterns of climatic variation. Canonical correlation analysis reveals strong and significant associations of heterozygosity at the ABO, Ss, Duffy, and P loci with climatic variability. Principal component analysis demonstrates that these loci tend to form correlated ensembles. Moreover, canonical correlation analysis of component scores provides support for an association between polymorphism at these loci and environmental variability. The results are concordant with two previous investigations which suggested a relationship between polymorphism for the ABO, Duffy, and Diego systems and climate. It is suggested that the examination of broad geographic patterns of genetic variation at multiple loci is a valuable, but underutilized, method of screening for the effects of long-term systematic pressures.

Climate↗
PubMed1985

Linkage analysis for psychiatric disorders. II. Methodological considerations.

Recent advances in molecular biology make genetic linkage analysis an increasingly attractive tool for the identification and characterization of genes involved in the etiology of psychiatric illnesses. However, the complex nature of psychiatric illnesses engenders a host of methodological difficulties not encountered in linkage analyses of simple, Mendelian genetic traits. A previous paper reviewed the basic concepts of genetic linkage analysis. This paper focuses on the methodological difficulties associated with the application of genetic linkage methods to psychiatric illnesses.

Age Factors↗
PubMed1985

Linkage analysis for psychiatric disorders. I. Basic concepts.

Within the last decade linkage analysis has become one of the most useful tools in the human genetics arsenal and is beginning to make substantial contributions in all areas of medicine. Its increasing popularity is a direct result of the burgeoning number of polymorphic markers that are now mapped to specific chromosomal locations. Within the near future the entire human genome is likely to be saturated. This paper is intended as an introduction to linkage analysis for non-geneticists. Basic methodological approaches, along with their strengths, weaknesses and assumptions are reviewed. A subsequent paper will critically review methodological difficulties in the application of linkage analysis to the psychiatric disorders.

Chromosome Mapping↗
PubMed1984

HLA and major affective disorder.

Fifteen unrelated multiplex families, each containing two or more offspring with a diagnosis of major affective disorder, were HLA typed to provide additional data bearing on the proposed linkage of affective disorder susceptibility genes with the major histocompatibility complex on chromosome 6. Altogether 19 parents, 38 affected children, and 13 unaffected children were typed. The distribution of shared HLA haplotypes among pairs of affected siblings, pairs of affected-unaffected siblings, and various diagnostic subsets of these families fails to lend any support for the HLA linkage hypothesis.

Adult↗
PubMed1984

A comparison of three affected-sib-pair scoring methods to detect HLA-linked disease susceptibility genes.

Two widely used affected-sib-pair scoring procedures (the Green and Woodrow [1977] procedure, and the method of forming all possible affected-sib-pairs) are compared with a new method for their relative efficiency in detecting the presence of an HLA-linked disease susceptibility gene. Their relative performance is investigated by extensive computer simulations over a large number of disease transmission models. On the average, the new procedure appears to outperform the Green and Woodrow method and the "all-possible-pairs" method.

Computers↗
PubMed1984

Histocompatibility leukocyte antigen and erythrocyte MNSs specificities in patients with meningitis or epiglottitis due to Haemophilus influenzae type b.

The frequencies of erythrocyte MNSs antigens and certain histocompatibility leukocyte antigen (HLA) specificities (HLA-A, HLA-B, and HLA-DR) were determined in white patients with meningitis or epiglottitis due to Haemophilus influenzae type b and in controls. The frequency of the erythrocyte MNSs genotype was significantly lower among patients with meningitis than among those with epiglottitis (P = 0.03); this observation confirms a trend observed previously. However, the frequencies of the HLA specificities did not differ significantly in the three groups studied; this result fails to confirm previous reports of disease associations with several HLA-A and HLA-B specificities. Although susceptibility to different clinical manifestations of haemophilus disease may be influenced by genetic factors, our studies indicate that the major loci conferring susceptibility are not in linkage disequilibrium with specificities in the major histocompatibility complex.

Antigens↗
PubMed1983

A genetic study of hyper-alpha-lipoproteinemia.

Because of its association with longevity and reduced incidence of coronary heart disease, it becomes important to find out how elevated HDL-cholesterol levels are determined. Analyses of family data from Cincinnati initially suggested environmental factors common to sibs; however, some form of dominant inheritance could not be ruled out. Reanalysis of the Cincinnati data by Iselius and Lalouel concluded against a major locus, but did identify three families as possibly segregating for a major locus. Analysis of an additional 26 kindreds from the same population in Cincinnati by Siervogel and associates concluded that a major gene could be causing familial aggregation of high density lipoprotein in white kindreds. In this analysis, we pooled all the white Cincinnati kindreds (n = 31), and investigated the familial transmission using complex segregation analysis. We failed to obtain clear evidence for major locus determination. Under the parsimonious hypothesis of no major locus, the polygenic heritability and common sibling environmental correlation were estimated as 0.531 and 0.263, respectively, consistent with other evidence.

Adult↗
PubMed1983

Alpha-1-antitrypsin-deficient phenotype is not maintained by segregation distortion.

Recent reports have suggested that the alpha-1-antitrypsin allele PiZ, which in homozygotes results in severe deficiency of this important protease inhibitor, is maintained at a relatively high gene frequency through the mechanism of segregation distortion. We report here on 121 nuclear families selected because only one parent was segregating the Z allele. After correcting for ascertainment, no evidence of preferential transmission was observed in 278 informative offspring.

Crosses, Genetic↗
PubMed1983

HLA and disease: haplotype sharing in multiplex families.

Recently it has been argued that the distribution of shared haplotypes in multiplex sibships for HLA-associated diseases may be an indicator of the disorder's underlying mode of transmission. Specifically, it has been suggested that the presence of multiple disease susceptibility genes and/or loci may be inferred when an inverse relationship between the amount of haplotype sharing and the number of affected sibs is observed in families where neither parent is affected. This claim is evaluated using extensive computer simulations. It is shown that a variety of haplotype sharing patterns are possible, even for the simplest models, and that for a large segment of the parameter space the actual distribution of shared haplotypes is opposite to that predicted. Accordingly, the inference that more than one locus is involved in the etiology of an HLA-associated non-Mendelian disease, if based only on the distribution of shared haplotypes in multiplex sibships, is unjustified.

Genetic Diseases, Inborn↗
PubMed1983

HLA sharing in multiplex sibships.

For an arbitrary number of affected sibs with unaffected parents, the proportion that share both marker haplotypes identical by descent is derived for the generalized single locus model. This proportion is shown to depend on the underlying parameters of the disease transmission model, on the total sibship size and on the number of sibs who are affected. The variety of identity by descent patterns suggests that any attempt to infer the presence of other independent disease susceptibility loci solely on the basis of an observed inverse relationship between the degree of haplotype sharing and the number of affected sibs, is liable to result in spurious conclusions.

Chromosome Mapping↗
PubMed1983

A sib-pair strategy for the use of restriction fragment length polymorphisms to study the mode of transmission of type II diabetes.

Three models for explaining the joint distribution of DNA insertional elements and type II diabetes in sibships are given as potential candidates for resolving the mode of transmission for this common non-Mendelian disorder. While the distributions predicted from all models are subject to the same rigid marginal constraints, only two models can be considered genetic (a combined major locus multifactorial background model and a two-locus model). A sequential probability ratio test is proposed to distinguish between these two models. Once the probands have been ascertained and using realistic parameter estimates, it is shown that, on the average, fewer than 100 affected sib-pairs are required to reach a decision at the 1% significance level with 99% power.

Base Composition↗
PubMed1982

Tangier disease: heterozygote detection and linkage analysis.

A large partially inbred kindred segregating Tangier disease is analyzed for linkage to seventeen informative markers. Three criteria were developed to classify heterozygotes and each criterion's validity was subsequently evaluated by assessing the pedigree distribution of diagnoses for internal consistency. The results of the linkage analysis, while varying with the diagnostic criterion used, yield no evidence of linkage to any of the markers studied. Tight linkage (less than 5 cM) to RH, MNSS, GPT, and GLO is ruled out by all criteria.

Adult↗
PubMed1982

Is the major histocompatibility complex linked to genes that increase susceptibility to affective disorder? A critical appraisal.

The evidence implicating genes linked to the major histocompatibility complex in the pathogenesis of affective disorder is reviewed, and 10 new multiplex families containing 26 affected siblings are presented. It is shown that when the data are properly analyzed by not dismantling multiplex sibships into all possible sib pairs, no individual data set presents compelling evidence of linkage. The present study is also negative. However, pooling all published families results in moderate evidence for nonrandom assortment.

Adolescent↗
PubMed1982

The distribution of HLA haplotypes in families with one untyped parent.

For non-Mendelian diseases, the distribution of shared haplotypes in multiplex sibships provides a powerful tool to investigate the hypothesis that disease susceptibility genes map in the neighborhood of the HLA complex. Occasionally, ambiguous sibships arise because all offspring inherit an HLA haplotype that is identical in state from an untyped parent. The scoring procedure developed here uses the population frequency of the haplotype as well as the sibship size to estimate the probability that, with respect to the untyped parent, all sibs are identical by descent. The resulting score from an ambiguous sibship can then be combined with scores from unambiguous sibships to form the statistic suggested by Green & Woodrow. It is shown that failure to include this type of ambiguous sibship may result in a significant loss of information.

Female↗