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Biomedical subjects

C Ober

Publications and source records attributed to C Ober.

100 records · Page 6Linked to original sources
PubMed1985

Frequency of diabetes mellitus in mothers of probands with gestational diabetes: possible maternal influence on the predisposition to gestational diabetes.

Interviews for genetic histories were conducted prior to delivery in 166 pregnant diabetic probands and 83 control gravidas with normal carbohydrate metabolism throughout gestation. A significant association was observed between parental diabetic phenotypes and type of diabetes in the probands (chi 2(12)) = 32.413; p less than 0.001). In particular a higher than expected number of mothers with diabetes was encountered in 91 probands with gestational diabetes mellitus. The findings are examined in relationship to the hypothesis that vulnerability to gestational diabetes may be increased by exposure to an abnormal environment during intrauterine development.

Adult↗
PubMed1984

Demographic components of gene frequency change in free-ranging macaques on Cayo Santiago.

Gene frequency profiles from January 1973 to January 1977 for three polymorphic loci were examined in Cayo Santiago rhesus social groups. The effects of demographic components (i.e., births, deaths, immigrations, emigrations, and group fission and fusion) on total change in gene frequencies are assessed. Allelic frequencies at the carbonic anhydrase II, 6-phosphogluconate dehydrogenase, and transferrin loci were analyzed in four social groups. In the two groups that underwent fission and fusion during the study period, the timing of these processes was related to the largest short-term changes in gene frequences. However, immigration and emigration had the greatest effect on total change in gene frequency in all groups during the study period. The relative importance of births and deaths in producing gene frequency change varied among the social groups. These results suggest that the relative importance of the demographic components of gene frequency change in primate populations is determined by behavioral patterns and ecological conditions specific to the population considered.

Animals↗
PubMed1982

A family study of spontaneous sister chromatid exchange frequency.

The frequency of spontaneous sister chromatid exchanges (SCEs) was determined in PHA-stimulated peripheral lymphocytes of 52 individuals, comprising 12 complete 2-generation pedigrees. Neither intraindividual variation between replicate cultures established from the same blood sample nor variation among samples from the same individual initiated at different times was significant. However, familial factors affecting mean SCE frequencies were indicated by detection of significant differences among, but not within, families. Although sample sizes were small, a genetic contribution to the SCE frequency was suggested by the observed pattern of familial correlations.

Adolescent↗
PubMedDate not supplied

A novel polymorphism in the 5' promoter region of the human interleukin-4 receptor alpha-chain gene is associated with decreased soluble interleukin-4 receptor protein levels.

Interleukin (IL)-4 exerts its biological effects through binding to the IL-4 receptor (IL4R) complex, plays a central role in stimulating B-cell differentiation, and is crucial for the development of T helper 2 cells. Recently, a soluble form of the human IL4R alpha chain (sIL4R alpha), which is produced by alternate mRNA splicing of exon 8, was discovered. sIL4R is thought to play an important role in either enhancing or inhibiting IL-4 signalling. We analyzed the 5' promoter region of the human IL4R alpha-chain gene (IL4RA) of healthy volunteers by DNA sequencing and found three novel single-nucleotide polymorphisms (SNPs; T-890C, T-1914C, C-3223T) and one novel short tandem repeat [(CAAAA)(5-7)-3600]. The two common promoter region SNPs T-1914C and C-3223T as well as six known coding SNPs in the IL4RA gene were genotyped in healthy blood donors by PCR with sequence-specific primers; total sIL4R levels were measured by ELISA. Results revealed a highly significant association of the -3223T variant with lowered sIL4R levels (two-tailed t-test, P=0.0002). Results remained highly significant after Bonferroni adjustment for multiple comparisons (P=0.0017). Moreover, the C-3223T variant was found to be in strong linkage disequilibrium with the extracellular 150V variant (P<0.001), which was recently described to be associated with atopic asthma in a Japanese population. Since this novel IL4RA promoter region SNP is common (allele frequency 29.8%), we conclude that it may be of importance for the genetic regulation of the IL-4 signalling pathway.

Gene Frequency↗
PubMedDate not supplied

HLA-G1 protein expression is not essential for fetal survival.

HLA-G is a nonclassical, class I HLA gene that is primarily expressed by fetal cells at the maternal-fetal interface and is thought to play a key role in the induction of tolerance in pregnancy. This paper reports the identification of a single base pair deletion at position 1597 (1597delC) in exon 3 (encoding the alpha2-domain) of HLA-G on 20 of 272 (7.4 per cent) African American chromosomes, three of 102 (2.9 per cent) Hispanic chromosomes, and none of 134 Caucasian chromosomes. This relatively common frameshift mutation results in amino acid substitutions in all of the residues in the second half of exon 3 including the conserved cysteine at codon 164. An adult individual was identified who was homozygous for this 'null' allele, and a first trimester placenta that was homozygous for 1597delC had no detectable HLA-G1 protein. These data indicate that expression of HLA-G1 protein is not essential for fetal survival.

Adult↗
PubMedDate not supplied

Studies of HLA, fertility and mate choice in a human isolate.

The role of human leukocyte antigen (HLA) genes in pregnancy and in human mate choice has been investigated in the Hutterites, an inbred population of European origins. High-resolution HLA haplotypes were defined by alleles at 16 loci in >1000 Hutterites. Prospective studies of pregnancy outcome previously demonstrated increased fetal loss rates among Hutterite couples matching for HLA-B antigens (P = 0.033) or for the entire 16-locus haplotype (P = 0.002). Among living children of couples matching for HLA-B or for the haplotype, there was a non-significant deficit of children who were heterozygous and compatible with the mother; the number of living children who were compatible and homozygous or incompatible and heterozygous was not different than expectations (HLA-B, P = 0.095; haplotype, P = 0.376). Mate choice among 411 couples was non-random with respect to the HLA haplotype, assessed by a variety of methods (P = 0.020 to <0.001). These combined data indicate a role for HLA region genes in both pregnancy outcome and mate choice, and suggest that selection acting on these genes occurs pre-conceptually as well as during pregnancy. This review outlines previously published studies on HLA, fertility and mate choice in the Hutterites.

Adult↗
PubMedDate not supplied

Analysis of HLA haplotype segregation in the Schmiedeleut Hutterites of South Dakota.

HLA data from 1,085 South Dakotan Schmiedeleut Hutterites were examined for evidence of nonrandom transmission of haplotypes. The inheritance of haplotypes was viewed as a series of genetic contests between competing pairs of parental haplotypes using a maximum likelihood approach first put forward by Carlisle and Woodbury. Haplotype transmission probabilities were expressed in terms of weights, and the null hypothesis that the inheritance pattern was a random stochastic process, equivalent to the equality of the weights, was tested via the likelihood ratio. A total of 1,517 competitions was subjected to analysis, first globally using all data, and then for particular haplotypes of interest. Transmission of haplotype observed to compete with only a single other haplotype was also assessed using an exact procedure. No evidence of preferential transmission of HLA haplotypes was found. These results do not rule out transmission biases that may arise because of selection against homozygotes, mechanisms specifically affecting particular alleles or haplotypes not considered in the present study, or biases arising from maternal-fetal interactions.

Consanguinity↗