Primary Lens Luxation
***Important Information About PLL ***
Lens Luxation is the dislocation or displacement of the lens within the eye. The lens is the clear structure in the eye,consisting of two rounded or conves surfaces,that focuses light rays to form an image onto the retina. Normally the lens is suspended between the iris ( the colored portion of the eye ) and the vitreous ( the clear gel in the back of the eye ), and is held in place by small fibers called zonules or suspensory ligaments.
Should the zonules break, the lens can either become partially dislocated (subluxated) from it normal position or completely dislocated ( luxation . When the lens detaches and falls forward into the anterior chamber in front of the pupil, it's called anterior luxation. When it falls back into the rear portion of the eye, it is called posterior luxation.
Primary Lens Luxation ( PLL )is an inherited disorder in which the zonuless or the suspensory fibers degenerate. The condition occurs mainly in the Terrier breeds,and sporadically in other breeds.Although the underlying reasons for the lens luxation are not well understood, inflammation or defect in the zonules may play a role. WIth PLL, both eyes are prone to dislocation of the lens. The typical age of onset for PLL is 4 to 8 yrs. A luxated lens will cause pain and inflammation and requires immediate veterinary attention. Expensive surgery is often indicated, and the dog's vision may or may not be able to be saved.
Until October 2009,there was no test available for PLL. The University of Missouri, College of Veterinary Medicine,through the partnership of OFA, now has a DNA test for this mutation.
The DNA test will categorize dogs as:
AFFECTED = Two mutated copies of the gene. At HIGH RISK for lens luxation and should NOT be used for breeding.
CARRIER = One normal and one mutated copy of the gene. At LOW RISK for lens luxation,but could pass either the normal copy or the mutated copy of the gene on its offspring. Carriers can be used for breeding, with caution... the only appropiate mate for carrier is a clear,so as not to produce any affected puppies.
CLEAR = Two normal and one mutated copy of the gene on its offspring. At NO RISK for lens luxation. Can only pass normal copy of the gene on to its offspring.
CLEAR BY PARENTAGE = Both Sire and Dam are clear, and that pair bred together can never produce an affected or a carrier. CLEAR x CLEAR is the ideal breeding pair.
Odds of in heritance for the PLL Gene:
CLEAR X CLEAR = 100% CLEAR
CLEAR X CARRIER = 50% CLEAR/50% CARRIER
CLEAR X AFFECTED = 100% CARRIER
CARRIER X CARRIER = 25% CLEAR/50% CARRIER/25% AFFECTED
CARRIER X AFFECTED = 50% CARRIER/50% AFFECTED
AFFECTED X AFFECTED = 100% AFFECTED
*** NOTE ***
We are in the process of testing all our rat terriers. Some have already been tested...Tests are easy to order and administer. Just follow directions carefully and sumit.
FROM THE OFA!!!!!
http://www.offa.org/dnatesting/pll.html
FROM CANINE GENETIC DISEASES!!!!!
http://www.caninegeneticdiseases.net/GLX/basicLUX.htm
FROM THE University of Missouri!!!!!
http://www.caninegeneticdiseases.net/GLX/PLLancmt.htm
FROM THE ANIMAL HEALTH TRUST!!!!!
http://www.aht.org.uk/cms-display/genetics_pll.html |
Date(s): September 30, 2010. Album by Green Acres Angels. 1 - 1 of 1 Total. 168 Visits. |
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