Quotes from studies and texts what I have found most intersting. Trying to collect more of these in time when I go trough all those studies what I have piled up. Akitas mentioned in these studies are most of the times American Akitas, but because breeds share the same genetic background and history we can study them together in most cases.
”LD is predicted to be most extreme in the Akita, a relatively rare breed with a restricted gene pool.”
The Canine genome (2005)
Elaine A. Ostrander and Robert K. Wayne
Genome research
”Dr. Angles and Dr. Pedersen looked at the diversity of alleles (or segments of genes) that occur alternately at a given location. In the sample group of 100 akitas, they found diversity of only six alleles at one MHC gen – a very low variance for what was believed to be unrelated donors. The biggest surprise was that one allele, an allele of the DRB1 gene, was found in 70% of the dogs. In this group of genes, heterozygosity improves disease resistance, this lack of variation in the MHC is considered to be major risk factor for autoimmune disease.”
Akita, treasure of Japan, nide 2
Barbara Bouyet
”Autoimmune disorders, affecting a wide range of organs and tissues, are becoming increasingly common in pure breeds of dogs. The main reason for this increase is inbreeding with a decrease in genetic diversity within the various genes of the DLA complex”
Determining whether risk for sebaceous adenitis of Standard Poodles is associated with a specific DLA class II genotype.
Principal Investigator: Niels C. Pedersen, Center for Companion Animal Health, UC Davis School
of Veterinary Medicine
”Hundreds of different dog breeds have now been established although the majority have only come into existence in the last two centuries. These breeds have largely been generated by the selection of gross phenotypic attributes particularly suited for work or decorative purposes, many being encoded by single gene mutations. A consequence of such a severe selection and inbreeding history is that many breeds have come from a relatively restricted gene pool.”
”As expected, the mongrels have the highest number of different alleles (22 out of 30 possible alleles tested).”
”The levels of homozygosity within these data were very high: 40.5%, 45.4% and 34.1% of dogs were homozygous at DLA-DRB1, DQA1 and DQB1, respectively. In total, 34.5% of animals were homozygous at DLA-DRB1 and DQA1 (n#757), 31.4% were homozygous at DLADQ (n#255), and 28.4% were homozygous at all three class II loci tested (n#225).”
”There may be consequences of the increased MHC homozygosity observed in some breeds, such as a polarization of the immune response depending on the antigen being presented. There are some
data in humans to suggest that MHC homozygous individuals have a reduced fertility and there are also reports of associations with repeated miscarriage. Similar effects may occur in dogs, especially in breeds that are very inbred. Some breeds certainly have much smaller litter sizes than others.”
Extensive interbreed, but minimal intrabreed, variation of DLA class II alleles and haplotypes in dogs (2002)
L.J. Kennedy, A. Barnes, G.M. Happ, R.J. Quinnell, D. Bennett, J. M. Angles, M.J. Day, N. Carmichael, J.F. Innes, D. Isherwood, S.D. Carter, W. Thomson, W.E.R. Ollier
”Loss of genetic diversity may also lead to increased risk for disease, with low levels of variation within the MHC suggested to increase susceptibility to infectious, autoimmune, and cancer disease.”
Uveodermatologic (VKH-like) syndrome in American Akita dogs is associated with an increased frequency of DQA1*00201 (2005)
J. M. Angles, T. R. Famula & N. C. Pedersen
”Of Asian dogs, the Korean native dogs, including the Sapsaree, Jindo, and HAD, showed a relatively higher polymorphism. In contrast, the Japanese native dogs exhibited low genetic variability among breeds and populations (mean expected heterozygosity #0.5), reflecting low intrabreed variation and extensive inbreeding.”
”The relationship trees based on Nei’s DA distance and the three-dimensional scattergram based on the principal components show that Japanese dogs have a high genetic variety among their native dogs, with relatively heterogeneous gene constitutions. The genetic variety of Japanese native dogs suggests that the dogs may consist of populations derived from several genetically different ancestral populations and their crossbreeds rather than from a single origin.”
Genetic Variability in East Asian Dogs Using Microsatellite Loci Analysis (2001)
K. S. Kim, Y. Tanabe, C. K. Park, and J. H. Ha
Explanations for acronyms (me so lazy and just adding texts from wikipedia etc)
LD - Linkage disequilibrium
”In population genetics, linkage disequilibrium is the non-random association of alleles at two or more loci, not necessarily on the same chromosome. It is also referred to as gametic phase disequilibrium, or simply gametic disequilibrium. In other words, linkage disequilibrium is the occurrence of some combinations of alleles or genetic markers in a population more often or less often than would be expected from a random formation of haplotypes from alleles based on their frequencies. It is not the same as linkage, which is the association of two or more loci on a chromosome with limited recombination between them. The amount of linkage disequilibrium depends on the difference between observed and expected (assuming random distributions) allelic frequencies. Populations where combinations of alleles or genotypes can be found in the expected proportions are said to be in linkage equilibrium.”
http://en.wikipedia.org/wiki/Linkage_disequilibrium
MHC - Major histocompatibility complex
”Major histocompatibility complex (MHC) is a cell surface molecule encoded by a large gene family in all vertebrates. MHC molecules mediate interactions of leukocytes, also called white blood cells (WBCs), which are immune cells, with other leukocytes or body cells. MHC determines compatibility of donors for organ transplant as well as one's susceptibility to an autoimmune disease via crossreacting immunization. In humans, MHC is also called human leukocyte antigen (HLA).
Protein molecules—either of the host's own phenotype or of other biologic entities—are continually synthesized and degraded in a cell. Occurring on the cell surface, each MHC molecule displays a molecular fraction, called epitope, of a protein, somewhat alike a hot dog (epitope) within a bun (MHC). The presented antigen can be either self or nonself. On the cell membrane, the MHC population in its entirety is like a meter indicating the balance of proteins within the cell.
The MHC gene family is divided into three subgroups—class I, class II, and class III. Diversity of antigen presentation, mediated by MHC classes I and II, is attained in multiple ways: the MHC's genetic encoding is polygenic, MHC genes are highly polymorphic and have many variants, several MHC genes are expressed from both inherited alleles.”
http://en.wikipedia.org/wiki/Major_histocompatibility_complex
DLA - Dog leukocyte antigen
”The dog leukocyte antigen (DLA) is a part of the major hisocompatability complex (MHC) in dogs, the DLA encodes for genes in the MHC. The DLA and MHC system are interchangeable terms in canines. The MHC plays a critical role in the immune response system and consists of three regions, class I, class II and class III. DLA is associated with the first two classes which are involved in the regulation of antigens in the immune system. The class II genes are highly polymorphic with many different alleles/haplotypes that have been linked to diseases, alergies, and autoimmune conditions such as diabetes, polyarthritus, and hypothyroidism in canines.”
http://en.wikipedia.org/wiki/Dog_leukocyte_antigen
HAD = Heterogeneous aboriginal dog
