The B subunit of coagulation factor XIII is linked to renin and the Duffy blood group to alpha-spectrin on human chromosome 1

Family linkage studies were used to detect two linkage relationships on human chromosome 1. The B subunit of coagulation factor XIII showed significant linkage to renin with a maximum lod score of 5.071 at a distance of 10 cM. Significant linkage was also shown between the Duffy blood group and alpha-spectrin with linkage results giving a combined lod score of 3.194 at 5 cM.     

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

Summary 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.     

The two apolipoprotein loci apoA-I and apoA-IV are closely linked in man

Summary 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 =0.00. 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.     

The human Duffy blood group in rhesus monkeys1

There is good evidence that susceptibility to Plasmodium vivax infection and to P. knowlesi erythrocyte invasion is influenced by certain human Duffy (Fy) blood group antigens. Since P. knowlesi readily infects rhesus monkeys (Macaca mulatto), it was not surprising to find an Fy-like antigen on rhesus erythrocytes. Using human Fy antisera in elution and absorption experiments, we found that all 40 rhesus monkeys tested displayed the Fy(a-b +) phenotype. Furthermore, the rhesus Fy^bantigen was inactivated by chymotrypsin but not by trypsin, suggesting that it is homologous to the human Fy^bantigen. Preliminary serological analyses and enzyme hydrolysis experiments suggest that none of the 13 blood group systems that we have described in rhesus are analogous to the human Fy system. Thus, it appears that there is no Duffy-like polymorphism in rhesus monkeys.     

Linkage analysis of the Duffy blood group marker with several chromosome 1 genes in an extended pedigree with Charcot-Marie-Tooth disease

Summary We have recently demonstrated tight linkage of the Duffy blood group marker to the -spectrin gene in an extended pedigree with Charcot-Marie-Tooth neuropathy. To determine a more precise location of the Duffy blood group locus on the chromosome 1 map we have tested several more chromosome 1 genes for linkage with this marker. We found suggestive linkage with the antithrombin III and apolipoprotein A2 genes and conclusive linkage with the gene coding for -nerve growth factor.     

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

Summary 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.     

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

Summary 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 = 0.18 in males, but +0.04 at =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 sex ratio of female/male recombination of 2.3.     

The genes for protamine 1 and 2 (PRM1 and PRM2) and transition protein 2 (TNP2) are closely linked in the mammalian genome.

The genes for two protamines (PRM1 and PRM2) and for two transition proteins (TNP1 and TNP2) have been characterized in several mammalian species. In the human, boar, and bull, the genes for PRM1, PRM2, and TNP2 are closely linked over a stretch of DNA 13-15 kb long. Although similar data are not yet available for the mouse and rat, our results suggest that the three genes are similarly linked in these species. The gene for TNP1 in all species studied is located on another chromosome.     

The CaTin1 (Capsicum annuum TMV-induced clone 1) and CaTin1-2 genes are linked head-to-head and share a bidirectional promoter

CaTin1 was expressed relatively early in the TMV-inoculated leaves of hot pepper which is resistant to TMV-P(0) infection. Interestingly, there was another homologous gene (CaTin1-2) located in front of CaTin1 in a head-to-head fashion and they shared a single promoter. The expression profile of the CaTin1-2 was very similar to CaTin1 in all the treatments except the slower induction time compared to CaTin1 upon TMV-P(0) inoculation. The promoter analysis of CaTin1 and CaTin1-2 revealed bidirectionality both in cis-elements and activity. The CaTin1-2 promoter had two TATA-boxes, four GCC-boxes, the root responsive element, and a W1-box. The ethylene-inducible promoter activity depended on GCC-boxes and TMV-inducible activity of the CaTin1-2 promoter reached its highest activity when this promoter had a W1-box.     

Receptors for Fc epsilon and Fc gamma are linked on mouse chromosome 1

Recently isolated cDNA clones for the high affinity Fc epsilon receptors on mast cells and basophils (Fc epsilon RI alpha) and Fc gamma receptors on macrophages and lymphocytes (Fc gamma 2b/gamma 1R) are homologous members of the Ig supergene family. Analysis of the segregation of restriction fragment length polymorphism in crosses of inbred mice now establish that the structural genes encoding both Fc epsilon RI alpha and Fc gamma 2b/gamma 1R are indeed discrete genes and are linked at the distal end of mouse chromosome 1. This finding raises the possibility that a family of Fc receptors could be found in a region that is known to contain immunologically important markers of lymphocyte surface Ag and autoimmune defects.