"Identifying mutations and patterns of their appearance and impact is important in furthering the biblical creation model. Genes affecting coloration are relatively easy to identify and several have been well studied. Here, variation in a gene affecting the development and movement of pigment cells, KIT, is examined. This complex gene codes for a complex protein important in a number of pathways. Many mutations have been identified in each of the species studied. Interesting examples of epigenetic modification and reversions have been documented in mice. This gene has shown up in surprising places in cats and dogs. Some mutations result in pleiotropy, although this is variable depending on genetic background, type of mutation, and location of the mutation. Mutations also
result in interesting variety including white animals and white spotting phenotypes.
Genes affecting coat color are relatively easy to discover and study since they obviously affect the appearance of the animal. So far, well over three hundred genes have been identified as affecting coat color in mammals. Some of these, such as the MC1R2 and ASIP3 genes, have been fairly well studied and useful information has been obtained by examining mutation patterns at these loci. Mutations in these genes affect proteins involved in the signaling pathway for pigment production and explain a large amount of the color variation in mammals.
One locus important in embryogenesis, KIT, has been associated with white coat patterns in several mammalian species and piebaldism in humans. The white areas are depigmented due to the absence of melanocytes, the cell type which produces pigment.
It encodes a receptor tyrosine kinase involved in the development and homeostasis of several cell lines including melanocytic (pigment), hematologic (blood), mast, and germ cells. This explains why heritable loss-of-function mutations sometimes have pleiotropic effects, not only resulting in white color patterns, but also anemia and/or infertility. Some of the stronger mutations cause a dominant white phenotype which is lethal in the homozygous condition.
The KIT gene is rather complex consisting of 21 exons in a 70 kb region. Most of the exons are relatively short (<300 bp). The exception is the final exon which not only codes the terminal portion of the receptor, but also includes a 2,147 bp non-coding sequence that follows. This complex organization of the gene reflects the complex nature of the protein receptor it produces.
KIT resides on the short arm of chromosome 8 in the pig (SSC 8p12). At least eight different alleles have been identified. The wild type (i) was identified in the European wild boar and most colored domestic European breeds. The belted phenotype (IBe) of the Hampshire was mapped to this locus and is believed to be the result of a regulatory mutation. This dominant allele, which produces a white belt around the shoulders and front legs, is carried in the homozygous state with no apparent ill effects.
Since pigs are unclean, a maximum of four KIT alleles would have been carried by the pair on the Ark. The number of alleles in domestic pigs is at least twice this, indicating that new alleles have arisen post-Flood by mutation at this locus. Researchers identify mutations as a change in nucleotide sequence relative to the wild type, which in this case is the European wild boar. In reality, the wild boar itself may carry mutations, but there are other details that can sometimes help to identify alleles carrying mutations. Alleles responsible for impaired migration of melanocytes, resulting in white coloration, can logically be inferred to carry mutations.
KIT resides on the long arm of chromosome 3 in the horse (ECA 3q). There are over 15 alleles; 14 of which are associated with some degree of depigmentation (white or white spotted phenotype). Roan
horses are characterized by white hairs interspersed with pigmented hairs throughout much of the body. This dominant phenotype is assumed to be lethal in the homozygote. It has been mapped to the KIT locus, although the causative mutation has yet to be identified.
In laboratory mice Kit is on chromosome 5 (MMU 5). There are 97 alleles, 66 of which arose via spontaneous mutation. These alleles, only some of which have had the underlying mutation identified, show a variety of phenotypes and pleiotropic effects.
In humans KIT resides on chromosome 4 (4q12). Loss-of-function mutations at this locus are associated with a condition known as piebaldism, a dominant disorder characterized by patches of white skin on the forehead, abdomen, and/or limbs. Thus far, nearly 50 different alleles have been identified in people exhibiting piebaldism including: 28 missense mutations, 5 splice mutations, 9 small deletions, 4 large deletions, and two small insertions. The extent of depigmentation tends to correlate with the region where the mutation occurs. Generally, mutations affecting the extracellular region of KIT are milder while those affecting the intracellular region are more severe.
KIT has a propensity to show up in unusual places. For example, an acute transforming feline retrovirus, Hardy-Zuckerman 4 feline sarcoma virus, was identified with the oncogene v-kit in its genome. This virus induces multicentric fibrosarcomas in the domestic cat. Compared to the cellular form (often called c-kit) there are some deletions at either end of the gene as well as a few point mutations.
KIT is an amazingly complex gene important in a number of critical pathways. Clearly there has been an increase in the alleles at this locus for the species examined here. The vast majority of these alleles are clearly the result of mutation given how they affect the function of the receptor.
One final observation about KIT mutations is their association with interesting variety. White horses have been admired throughout history and are important in biblical prophecy. White sows are very popular because of their high productivity and good mothering ability. White coloration in animals and a white forelock in humans certainly add to the variety and beauty found in creation."
CMI
And I saw, and behold a white horse:
Revelation 6:2
Genes affecting coat color are relatively easy to discover and study since they obviously affect the appearance of the animal. So far, well over three hundred genes have been identified as affecting coat color in mammals. Some of these, such as the MC1R2 and ASIP3 genes, have been fairly well studied and useful information has been obtained by examining mutation patterns at these loci. Mutations in these genes affect proteins involved in the signaling pathway for pigment production and explain a large amount of the color variation in mammals.
One locus important in embryogenesis, KIT, has been associated with white coat patterns in several mammalian species and piebaldism in humans. The white areas are depigmented due to the absence of melanocytes, the cell type which produces pigment.
It encodes a receptor tyrosine kinase involved in the development and homeostasis of several cell lines including melanocytic (pigment), hematologic (blood), mast, and germ cells. This explains why heritable loss-of-function mutations sometimes have pleiotropic effects, not only resulting in white color patterns, but also anemia and/or infertility. Some of the stronger mutations cause a dominant white phenotype which is lethal in the homozygous condition.
The KIT gene is rather complex consisting of 21 exons in a 70 kb region. Most of the exons are relatively short (<300 bp). The exception is the final exon which not only codes the terminal portion of the receptor, but also includes a 2,147 bp non-coding sequence that follows. This complex organization of the gene reflects the complex nature of the protein receptor it produces.
KIT resides on the short arm of chromosome 8 in the pig (SSC 8p12). At least eight different alleles have been identified. The wild type (i) was identified in the European wild boar and most colored domestic European breeds. The belted phenotype (IBe) of the Hampshire was mapped to this locus and is believed to be the result of a regulatory mutation. This dominant allele, which produces a white belt around the shoulders and front legs, is carried in the homozygous state with no apparent ill effects.
Since pigs are unclean, a maximum of four KIT alleles would have been carried by the pair on the Ark. The number of alleles in domestic pigs is at least twice this, indicating that new alleles have arisen post-Flood by mutation at this locus. Researchers identify mutations as a change in nucleotide sequence relative to the wild type, which in this case is the European wild boar. In reality, the wild boar itself may carry mutations, but there are other details that can sometimes help to identify alleles carrying mutations. Alleles responsible for impaired migration of melanocytes, resulting in white coloration, can logically be inferred to carry mutations.
KIT resides on the long arm of chromosome 3 in the horse (ECA 3q). There are over 15 alleles; 14 of which are associated with some degree of depigmentation (white or white spotted phenotype). Roan
In laboratory mice Kit is on chromosome 5 (MMU 5). There are 97 alleles, 66 of which arose via spontaneous mutation. These alleles, only some of which have had the underlying mutation identified, show a variety of phenotypes and pleiotropic effects.
In humans KIT resides on chromosome 4 (4q12). Loss-of-function mutations at this locus are associated with a condition known as piebaldism, a dominant disorder characterized by patches of white skin on the forehead, abdomen, and/or limbs. Thus far, nearly 50 different alleles have been identified in people exhibiting piebaldism including: 28 missense mutations, 5 splice mutations, 9 small deletions, 4 large deletions, and two small insertions. The extent of depigmentation tends to correlate with the region where the mutation occurs. Generally, mutations affecting the extracellular region of KIT are milder while those affecting the intracellular region are more severe.
KIT has a propensity to show up in unusual places. For example, an acute transforming feline retrovirus, Hardy-Zuckerman 4 feline sarcoma virus, was identified with the oncogene v-kit in its genome. This virus induces multicentric fibrosarcomas in the domestic cat. Compared to the cellular form (often called c-kit) there are some deletions at either end of the gene as well as a few point mutations.
KIT is an amazingly complex gene important in a number of critical pathways. Clearly there has been an increase in the alleles at this locus for the species examined here. The vast majority of these alleles are clearly the result of mutation given how they affect the function of the receptor.
One final observation about KIT mutations is their association with interesting variety. White horses have been admired throughout history and are important in biblical prophecy. White sows are very popular because of their high productivity and good mothering ability. White coloration in animals and a white forelock in humans certainly add to the variety and beauty found in creation."
CMI
And I saw, and behold a white horse:
Revelation 6:2
