Genetics 101: Autosomal Recessive Genes and Lens Luxation
Researchers believe that lens luxation is an autosomal recessive trait involving a single gene. If this is the case, the following principles can give the breeder an idea of the probability of risk the puppies of a particular breeding will have of being affected by lens luxation, or the risk of being a carrier or being clear.
If both parents are clear (no genes for the disease whatsoever), all the puppies will be clear.

If one parent is clear and one parent is a carrier, half of the puppies will be clear and half will be carriers. Another way to look at it is, one puppy has a 50% chance of being either clear or a carrier.

If one parent is clear and one parent is affected, all puppies have the strong probability of being carriers.

If both parents are carriers, the odds are that 50% of the puppies will be carriers, 25% will be clear of the gene and 25% will be affected.

If one parent is a carrier and one parent is affected, 50% of the puppies will be affected and 50% will be carriers. There will be no clear puppies.

If both parents are affected, all puppies will be affected.

both genes normal

one gene normal
one gene for LL
no visible signs of LL

has both genes for LL
dog will have LL
Genotype: the genes or potential traits - what you don't see.
Phenotype: the outward appearance - what you do see. A carrier would have the appearance of being normal even though it has one gene for lens luxation.
This document prepared by Leslie Manis, ASTC Health/Genetics Chairman.
Copyright 2008-2010, American Sealyham Terrier Club