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T Gedde-Dahl

Publications and source records attributed to T Gedde-Dahl.

At least 91 records · Page 5Linked to original sources
PubMed1985

Genetic polymorphism of complement component C8.

Extensive genetic polymorphism of complement component C8 was demonstrated by isoelectric focusing of serum or plasma samples followed by immunoblotting procedures. Using these methods, we could detect both alpha-gamma (C81) and beta (C82) chain polymorphisms in the same gel. Two-dimensional (2D) electrophoresis of C8 immunoprecipitates was used to obtain further information of the C8 patterns. Evidence was obtained that the C81 polymorphism resides in the structural gene of the C8 alpha chain. Both C8 systems show autosomal, chiefly codominant inheritance, and the distribution of phenotypes agrees with the Hardy-Weinberg equilibrium. Our findings suggest at least five different alleles in the C81 system; the gene frequencies of the two most common ones, C81*A and C81*B being 0.59 and 0.39, respectively. In C82 we found evidence for at least three codominant alleles, the gene frequencies for the two most common ones, C82*B and C82*A being 0.94 and 0.05, respectively. In addition, family studies disclosed the existence of a null allele, C82*Q0.

Alleles↗
PubMed1985

Osteosarcoma and retinoblastoma: a shared chromosomal mechanism revealing recessive predisposition.

Survivors of the heritable form of retinoblastoma subsequently develop second primary osteosarcomas at substantially greater frequency than either the general population or survivors of nonheritable retinoblastoma. Here we present molecular genetic evidence that the development of these two disparate tumor types involves specific somatic loss of constitutional heterozygosity for the region of human chromosome 13 that includes the RB1 locus. Similar events occur during the genesis of nonheritable osteosarcoma but not in several other embryonal tumors or sarcomas. These findings suggest that a conceptual approach toward defining the number of genes whose recessive mutant forms predispose to cancer is the molecular genetic analysis of clinically associated tumor types. They also suggest that the molecular basis of mixed cancer families may be the differential expression of a single pleiotropic recessive mutation by tissue specific mitotic segregation abnormalities.

Alleles↗
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↗
PubMed1984

The locus for apolipoprotein E (apoE) is close to the Lutheran (Lu) blood group locus on chromosome 19.

Linkage has been described between the loci for apolipoprotein E (apoE) and the complement C3 (C3) on chromosome 19. C3 is known to belong to a linkage group with gene order C3-Se-Lu. The present study revealed linkage between Se and apoE with peak lod score +3.3 at recombination fraction 0.08 in males and +1.36 at 0.22 in females, and linkage between apoE and Lu with lod score +4.52 at zero recombination in sexes combined. The C3-apoE linkage gives lod score +4.00 at theta = 0.18 in males, but +0.04 at theta = 0.45 in females. Triple heterozygote families confirm that apoE is on the Se side and on the Lu side of C3. Allelic association between apoE and Lu has not been ruled out. Combining our data with published data on C3-Se and Se-Lu, this segment of chromosome 19 has an average age sex ratio of female/male recombination of 2.3.

Alleles↗
PubMed1984

The two apolipoprotein loci apo A-I and apo A-IV are closely linked in man.

In man the closely linked genes for the apolipoproteins A-I and C-III have been assigned to chromosome 11. Linkage studies performed in a Norwegian family with a mutant apoA-I gene established a close linkage between the loci for apoA-I and apoA-IV. For both sexes combined, the peak lod score was 3.01 at a recombination fraction of 0 = 0.00. Thus this study adds the locus of apoA-IV to the previously reported apolipoprotein gene cluster on chromosome 11. The previously unidentified polymorphic serum protein, USP1, is by immunochemical and electrophoretical methods identified as apoA-IV. ApoA-IV typing should be a valuable tool in elucidating the genomic organization of chromosome 11.

Apolipoproteins A↗
PubMed1984

The locus for apolipoprotein CII is closely linked to the apolipoprotein E locus on chromosome 19 in man.

We have demonstrated close linkage between the genes for apolipoprotein E (apoE) and apolipoprotein CII (apoCII). Families segregating for apoE protein variants were screened for a DNA restriction fragment length polymorphism close to the apoCII gene by using an apoCII cDNA clone. The maximum lod score is 4.52 (sexes combined) at a recombination frequency of zero. Given linkage, it may be assumed that no recombinations have happened in altogether 33 observed meioses. It is therefore evident that the apoCII gene is situated on chromosome 19, close to the apoE gene.

Apolipoprotein C-II↗
PubMed1983

Genetic studies of an apoA-I lipoprotein variant.

ApoA-I is the major apolipoprotein component of human high density lipoproteins (HDL). By a 2-D electrophoretic study of serum samples from Norwegian families, an apoA-I variant (apoA-I 2-1) was detected in a healthy individual. In the present study performed to elucidate formal and population genetic aspects of apoA-I, this variant was observed in 4 generations of the family of the propositus. One homozygous individual was found. A codominant autosomal Mendelian inheritance was established for the variant. Two heterozygotes were found among 124 unrelated individuals tested. The apoA-I 2 allele frequency was calculated as 0.008 in this population sample.

Apolipoprotein A-I↗
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↗
PubMed1982

Fibrinogen gamma chain locus is on chromosome 4 in man.

A molecular fibrinogen variant has been detected by two-dimensional electrophoresis of human plasma samples. Fibrinogen is a complex molecule consisting of three different polypeptide chains A alpha, B beta, and gamma. The presently described variation resides in the gamma-chain, which in the variant is slightly more basic and heavier than the common form of this chain. In a family material it has been shown that the variant is genetically determined, and the segregation pattern shows autosomal codominant inheritance. The family material has been typed in approximately 30 marker systems, and linkage studies have shown close linkage between the gamma-chain locus (FGG) and MNSs. The MNSs loci are known to be located on chromosome 4 in humans and the fibrinogen gamma-chain locus is thus on this chromosome. The MNSs/FGG distance is approximately 8 centimorgans. Supplementing data suggest that FGG is distal to MNSs on the long arm of chromosome 4.

Chromosome Mapping↗
PubMed1982

The locus for apolipoprotein E (apoE) is linked to the complement component C3 (C3) locus on chromosome 19 in man.

By two-dimensional electrophoresis of human serum a genetically determined polymorphism of apolipoprotein E (apoE) can be demonstrated. Three alleles occur with appreciable frequency in Caucasian populations. In the present study the segregation of apoE and complement component C3 (C3) types in material from Norwegian families has been studied. Linkage has convincingly been demonstrated between the two loci with a lod score of 3.00 in males at a recombination fraction of 13%. As it is known that the C3 locus is situated on chromosome 19 in man, apoE can be located to this specific chromosome. Positive linkage data do not, to our knowledge, at present exist with regard to other apolipoproteins.

Adult↗
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↗
PubMed1981

The Gm--Pi linkage heterogeneity in view of Pi M subtypes.

In this study linkage between the loci for Gm (gamma-type heavy-chain immunoglobulin markers) and Pi (alpha 1-antitrypsin/alpha 1-protease inhibitor) has been shown in families segregating for the Pi M subtypes (M1, M2, M3 and Msal) as identified by separator isoelectric focusing . The estimate for the Gm--Pi (M type) recombination is 0.29 (95% limits 0.24--0.37) at a peak lod score of 4.31 and with no sex difference. This value is not significantly different from updated recombination frequency estimates for Gm--Pi in Pi MS (0.26) and Pi MZ, SZ and FZ families (0.21). The overall Gm--Pi recombination fraction estimate of 0.26 (95% limits 0.23--0.30) at a peak lod score of 20.75 must now be considered as solid. There is a significant heterogeneity within the male Pi MZ families in that the new Finnish families show a higher recombination between Gm and Pi. There is also a possible segregation distortion (Z:M = 23:8). The heterogeneity is discussed in terms of haplotypes, the behaviour of which could be determined by linked genes or chromosomal rearrangements. The possibility that the alpha 1-antitrypsin level influences recombination frequency has not been ruled out, but cannot explain the heterogeneity within Pi MZ families.

Alleles↗