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C1-42 Factors That Complicate Interpretations of Inheritance
Genetics Stuff
10
Biochemistry
09/20/2010

Additional Biochemistry Flashcards

 


 

Cards

Term

 

 

 

Germline Mosaicism

Definition

All or part of the germline of an individual contains an allele not present in the somatic cells.

 

Recurrence risk for future offspring of the mosaic parent is increased

Term

 

 

Reduced penetrance

Definition

- the expression of the disease phenotype by less than 100% of the individuals who possess the disease-causing genotype.


ex. Retinoblastoma (90% penetrance)

Term




Delayed Age of Onset

Definition

Clinical expression of some genetic diseases does not occur in infancy and affected individuals are not diagnosed until later in life.

ex Huntington's  Disease

Term

 

 

 

Variable Expression

Definition

Expression of the phenotype varies greatly in severity in some disorders.

If the phenotype is expressed to any degree the disorder is penetrant.

Term

 

 

 

Factors that influence Variable Expression

Definition

- enviornmental factors

- modifier genes

- allelic heterogeneity 

- locus heterogeneity

Term



 

Allelic heterogeneity 

Definition

-different alleles (mutations) at a specific locus can produce varying expression of a disease

Term

 

 

 

Locus heterogeneity 

Definition

 A single disease phenotype caused by mutations at different loci in different families

Term




Sex-limited traits

Definition



Traits that are expressed in only one of the sexes due to gender specific differences, such as anatomical differences.

Term




Anticipation

Definition

Progressively earlier or more severe expression of a disease in the most recent generations
Expansion of DNA repeats is the cause of anticipation in some diseases.

 

Term



Affected females with an X-linked recessive disorder:

Definition

Manifesting heterozygote: Skewed inactivation with greater representation of the mutant allele in the active X chromosomes
About 5% of female carriers of hemophilia A have factor VIII levels low enough to be considered mild hemophiliacs
Turner syndrome: female with only one X chromosome - 45,X.
Translocations or deletions of the X chromosome
Homozygous female: father affected and mother a carrier