PubMed Health⌕ Search

Biomedical subjects

R Jonassen

Publications and source records attributed to R Jonassen.

14 recordsLinked to original sources
PubMed1992

Linkage and association studies with C8A and C8B RFLPs on chromosome 1.

Linkage relations for the C8A and C8B BamHI RFLPs have been investigated. A peak lod score of 4.52 at recombination fraction zero was obtained between the two C8 genes. Combined with our previously obtained linkage data (Rogde et al. 1986) the maximum lod score is 7.53 at recombination fraction zero. The compiled C8-PGM1 linkage data from this and the previous study gave a maximum lod score of 22.02 at recombination fraction 0.11 (0.07-0.16) with no sex difference. A chromosome 1p reference marker, D1S57, has been applied in this linkage study. A maximum lod score of 5.06 between the C8 cluster and D1S57 at theta = 0.18 (0.11-0.28) was recorded. The linkage analyses and triply informative families gave evidence that the C8 loci are situated about halfway between PGM1 and D1S57 on the short arm of chromosome 1. There was no evidence of allelic association between the C8A and C8B BamHI RFLPs in 62 unrelated haplotypes.

Chromosome Mapping↗
PubMed1988

Restriction fragment length polymorphisms of the complement component C4 loci on chromosome 6: studies with emphasis on the determination of gene number.

Restriction fragment length polymorphisms of the C4 region of human chromosome 6 have been studied in family material where the haplotypes are defined with regard to other genetic markers in this region. Employing one near full-length C4 probe and the combination of BglII and XbaI enzymes, five different C4 genes were characterized. Studies of the segregation of DNA patterns in families made possible the reliable determination of DNA C4 haplotype pattern including gene number. In the total material of 76 haplotypes, 13 different types with regard to number and/or DNA type of C4 gene(s) were encountered. Twelve of the haplotypes had one C4 gene only, 58 had two genes, while 6 had three C4 genes. This fits fairly well with the hypothesis that the one- and three-gene haplotypes have originated through unequal crossing-over between chromosomes carrying duplicated C4 genes.

Blotting, Southern↗
PubMed1987

Identification in blood stains through DNA typing with C4 and HLA-DR probes.

A restriction fragment length polymorphism analysis using double digestion of DNA preparations with XbaI and BglII restriction enzymes and hybridization with C4 and HLA-DR probes is described. The typing conditions selected reveal extensive individual variation in both C4 and DR gene regions. In our panel of 46 unrelated individuals, 37 different phenotypic patterns were recognized when both probes were used, and preliminary discriminative power values of 0.865 and 0.914 were calculated for C4 and DR beta, respectively. The probability of a chance match using both systems is probably about 1.5.10(-2). The potential of this method for individual identification of blood stains was demonstrated on DNA prepared from 6-month-old dried blood stains from seven panel individuals. The seven individuals were all identified when comparing stain DNA patterns with panel control patterns. No RFLP pattern changes were observed following storage of blood stains. Based on these experiments with C4 and DR beta DNA typing under laboratory conditions, it is concluded that DNA typing with such probes may become a powerful tool in future stain identification analyses.

Blood Grouping and Crossmatching↗
PubMed1985

A structural locus for coagulation factor XIIIA (F13A) is located distal to the HLA region on chromosome 6p in man.

Linkage between the locus for coagulation factor XIIIA (F13A) and HLA-region genes has been revealed during a linkage study between F13A and approximately 40 other polymorphic marker genes. In males, the maximum lod score between F13A and HLA-region genes (HLA-A, -C, -B, -DR; C4A, -B; Bf; and/or C2) is 7.60 at theta 1 = .18. To GLO, the maximum lod score is 2.37 at theta 1 = .19; to PGM3, .22 at theta 1 = .35. Female data indicate a clear sex difference in recombination frequency between F13A and HLA. The present findings, in combination with earlier knowledge of PGM3/GLO/HLA localization and gene distances, show that F13A is distal to HLA on the short arm of chromosome 6 in man. It is thus likely that by including FXIIIA typing in linkage studies, the whole male 6p is within mapping distance of highly polymorphic, classical marker genes. Earlier findings that the Hageman factor gene (F12) is located in the same chromosomal region may indicate the presence of a coagulation factor gene cluster in this region.

Chromosome Banding↗
PubMed1983

Gene order and gene distances in the HLA region studied by the haplotype method.

The present report describes a method to establish gene order and gene distances in chromosomal regions where several genes are located closely together. The method is applied to the study of the complement loci in the HLA complex on chromosome 6 in man. The method is based on allelic association, i.e. alleles of closely linked loci are nonrandomly associated on haplotypes. A haplotype which yields information has a frequency higher than would be expected from the frequencies of each of its alleles. They occur, moreover, with a frequency which makes them the main source of the least frequent of the alleles in the combinations. Other haplotype combinations involving this allele (these alleles) are most likely the results of recombinational events involving a main haplotype. Such crossovers may therefore, on certain conditions, be used for gene mapping purposes. Some basic rules for the use of the method are given. A total of 701 haplotypes involving the short arm of chromosome 6 have been studied. Typings have been performed with regard to HLA-A, -B, -C, -D/-DR, C4, C2 and Bf. The study confirms previous localization of the complement loci between HLA-D and -B. The investigation suggests the order HLA-D-Bf-C4-C2-HLA-B. There is, moreover, slight evidence in favour of a localization of the C4A gene on the HLA-B side of C4B. Given an HLA-A-HLA-B distance of 0.8 cM, suggested relative distances are: HLA-D-Bf:0.44 cM, Bf-C4:0.04 cM, C4-C2:0.11 cM, and C2-HLA-B:0.12 cM.

Alleles↗
PubMed1981

The ESD polymorphism: further studies of the ESD2 and ESD5 allele products.

Electrofocusing and agarose electrophoresis techniques both reveal polymorphism of ESD2, which may be subdivided into two different proteins, coded for by genes allelic to EDS* 1. After agarose electrophoresis, ESD2 is slightly more anodally located than ESD5, while the latter is considerably more acidic as revealed by electrofocusing in polyacrylamide gel slabs. Family studies have confirmed that each of the allele products behave as Mendelian characters; and the gene frequencies in a Norwegian population material are about 0.08 and 0.02 for the ESD*2 and ESD*5 alleles, respectively.

Adult↗
PubMed1981

Complement loci of the HLA complex. Studies on families with intra-HLA crossovers and haplotype associations.

We report genetic studies of families with defined crossovers in the HLA complex. Haplotypic associations between the different alleles have been analyzed. The object of the studies has been to determine the precise location of complement loci on the HLA complex on chromosome 6. Based on direct observation of recombinations and on indirect evidence from haplotypes, we postulate that the C4 and Bf loci are located between the HLA-B and -D regions and probably closer to the former. Available information also points towards the same localization for the C2 locus.

Alleles↗
PubMed1979

The C4 system: formal and population genetics.

The present study shows that the C4 system as investigated by high voltage agarose gel electrophoresis is highly polymorphic. In a series of unrelated Norwegian adults, where C4 types have been ascertained through segregation in families, six different haplotypes have been found to occur with a frequency exceeding 1%. The genotype frequencies in the population fit expected Hardy-Weinberg distribution. In family material comprising 89 matings with 327 children the distribution of offspring is as expected according to autosomal codominant inheritance of haplotypes.

Complement C4↗
PubMed1977

The genetic polymorphism of the fourth component of human complement: methodological aspects and a presentation of linkage and association data relevant to its localization in the HLA region.

The C4 polymorphism in man has been studied by immunofixation electrophoresis, crossed immunoelectrophoresis, and functional detection after agarose gel electrophoresis. It has so far not been possible to reveal this polymorphism by isoelectric focusing and functional detection of C4 bands. Three common alleles and one less frequently occuring allele have been identified. In a small population sample studied by all the different techniques and verified by family segregation, the following gene frequencies have been found: C4F: 0.46, C4S: 0.32, C4F1: 0.20, and C4M: 0.02. By linkage and association studies in a family material it has been shown that a structural C4 locus is situated in the HLA region of chromosome 6 very close to the HLA-B and Bf loci.

Adult↗
PubMed1976

ESD polymorphism in Norway.

ESD phenotype distribution and allele frequencies in 217 Norwegians and 196 Norwegian Lapps are presented. There is good accordance with Hardy-Weinberg distribution, ESD1 allele frequencies are 0.887 in the Norwegians and 0.872 in the Lapps.

Adult↗
PubMed1976

GLO polymorphism in Norway.

GLO phenotype distribution and GLO allele frequencies in samples of the Norwegian population and the Lappish minority of Norway are presented. The GLO frequency is 0.442 in 216 Norwegians, while it is 0.304 in 184 Lapps; the difference is statistically significant. There are furthermore probably differences in gene frequencies between two main groups of Lapps.

Erythrocytes↗