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  PRINTABLE WORD DOC

" RECESSIVE GENE INHERITANCE PATTERN "

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GENETIC CHART

Applicable to GM-1 and PRA

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BACK TO THE ARTICLE : FACTS ABOUT PROGRESSIVE RETINAL ATROPHY ( PRA )

 

NORMAL

  -represent genetic : NORMAL

CARRIER

  -represent genetic : CARRIER

AFFECTED

  -represent genetic : AFFECTED

 

These are only six possibilities for mating.

  Each of our dogs is the product of one of

these six breeding combinations.

 

Both GM-1* and PRA, Progressive Retinal Atrophy,

are recessive genes.

 

This chart can be applied to the

genetic inheritance pattern of each disease.

 

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EXPECTED AVERAGE RESULT, BASED ON A MINIMUM OF 16 PUPPIES

PARENTS

OFFSPRING

 

 

Expected average result, based on a minimum of 16 puppies

  Both parents are NORMAL, not carrying the recessive gene.

  100 % of the puppies will be NORMAL.

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PARENTS

OFFSPRING

 

Expected average result, based on a minimum of 16 puppies

  One parent is NORMAL, one parent is CARRIER of the recessive

  gene ... 50 % of the offspring will be NORMAL, 50 % will be

  CARRIERS.

 

  In "Storage" disease Carriers can be detected by a blood assay.

  In PRA, Carriers can not be detected that easily thus pedigree

  analysis is critical

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PARENTS

OFFSPRING

 

Expected average result, based on a minimum of 16 puppies

  An AFFECTED parent will always produce CARRIER offspring.

  In this situation, only 50 % of the offspring will be AFFECTED,

  but the other 50 % will still be CARRIERS.

 

 

  AFFECTED individuals used for breeding automatically identify

  their offspring's as CARRIERS.

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PARENTS

OFFSPRING

 

Expected average result, based on a minimum of 16 puppies

  CARRIER to CARRIER breedings will produce 25 % AFFECTED

  offspring ; 25 % NORMAL offspring ; and 50 % CARRIERS. 

 

  In "Storage" disease, the process of genetic identification has

  been simplified for us. In PRA, the identification of the

  different offspring's genetic make-up is extremely complex.

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PARENTS

OFFSPRING

 

Expected average result, based on a minimum of 16 puppies

  An AFFECTED parent will always produce 100 % CARRIER

  offspring.

 

  AFFECTED parent breed to  NORMAL parent will not produce

  any AFFECTED offspring, but they will all be CARRIERS.

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PARENTS

OFFSPRING

 

Expected average result, based on a minimum of 16 puppies

  AFFECTED parent bred to AFFECTED parent will always

  produce all AFFECTED offspring.

 

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