Gene insertion underlies origin of Dachshunds

According to a new study, researchers have discovered that an evolutionary event is the cause behind short, curved legs that characterize certain dog breeds like dachshunds. This particular finding provides with information about how physical differences are created within species and also suggests new methods of understanding human dwarfism.

Dogs have a number of ranges of body types and behaviors. This diversity in them makes them ideal for studying genes that effect body type and shape.

The disproportional dwarfism, or chondrodysplasia, in dogs is caused due to calcification of growth plates, which prevents long bone development and results in short legs with a curved appearance.

To understand this particular problem, researchers of NIHai??i??s National Human Genome Research Institute, has examined DNA samples of 835 dogs from 76 distinct breeds, including 95 dogs from 8 breeds with short legs. The researchers examined more than 40,000 markers of DNA variation.

From the study, the researchers specifically found that short-legged dog breeds have an extra copy of gene that codes for a growth-promoting protein called fibroblast growth factor 4 (FGF4). Though it is active, but it lacks certain parts of the DNA code, called introns, found in normal genes.

According to researchers, this extra gene is so – called retrogene evolved in the dog genome when the ancestor of modern dog breeds diverged from wolves.

These findings conclude that retrogenes may play an important role in creating differences within species than previously thought. They may also have an effect in understanding human biology and disease. The study also points at a new gene which should be investigated. It may prove to be useful in human hypochondroplasia.

Source – National Institutes of Health

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