Module 3: Mendelian Inheritance Patterns Flashcards
Gene Disorder
- Caused by DNA changes in a specific gene - isn’t always just one
- Follow patterns of inheritance
- Can also be new & passed to children
De novo
- New mutation in individual that was not in previous generation
- Usually either at the egg or sperm level or early in development
4 Patterns of Inheritance
- Autosomal Dominant
- Autosomal Recessive
- Mitochondrial
- X-linked
Autosomal Recessive Conditions
- Dominant allele is the wild type
- Recessive allele is mutated
- Only 1 normal copy of the normal allele is needed for normal function
What is the % risk of an affected child if both parents are carriers for an autosomal recessive condition?
25%
What is the % risk of an affected child if one parent is a carrier for an autosomal recessive condition?
0%
Consanguinity
The increased chance of a recessive condition caused by reproduction between blood relatives
Autosomal Dominant Conditions
- Dominant allele is mutated
- Only need 1 copy of the mutated gene to express the condition
- Homozygous mutations are often lethal or severe
What is the recurrence risk for each child of an affected individual?
50%
Dominant Negative Effect
The altered protein that is produced interacts abnormality with other normal proteins
Haploinsufficiency
When a mutagen prevents the production of the full amount of proteins
Gain of Function
Mutated protein has a different function that alters development
X-linked Conditions
- Conditions caused by variants in genes on the X chromosome
- No male to male transmission, but usually affects males more
- Females can show clinical signs if both X’s are affected
Mitochondrial DNA
- Maternal/powerhouse DNA
- Passed through egg only
What is the chance for a couple to have an UNAFFECTED child if both parents are AR carriers of the same condition?
75%
