Patterns Of Inheritance I Flashcards
Pleiotrophy
The mutation produces multiple distinct phenotype so that may or may not appear in a particular individual
Why are pedigrees useful
Is the trait heritable
Chromo location of cause genes
Risk to other family members
Proband
Isolated case of a genetic disorder involving a family member who draws attention to a pedigree
Index case
The clinically affected family member through whom attention is first drawn to a pedigree of particular interest to human genetics
Penetrance
The probability that a gene will have any phenotypic expression at all
Expressivity
The severity of expression of the phenotype
Pleiotropy
When an allele of a gene produces several phenotypic effects
Autosomal Dominant Inheritance Characteristics
- Multiple generations affected
- Males and females are equally affected
- Male to male transmission
- Each offspring has a 50/50 chance of being affected to unaffected
AD disorders that are homozygous are…
Lethal
Examples of AD diseases
Polycystic Kidney Disease
Defect in PKDI on 16p13
Onset when 40-50
Autosomal recessive characteristics
Parents can be unaffected
Equal expression in both sexes
Examples of AR inheritance diseases
Taysachs disease
Accumulation of gangliosides in neurons
PKU
AR disease involving mental retardation and can be averted with proper dietary considerations in a timely fashion
Consanguinity
Genetic relationship where individuals have at least one common ancestor in the preceding few generations
First Degree Relatives
50% of genes shared
Includes parents, siblings, and offspring