Mendelian Disease Flashcards
Definition of mendelian disease
Caused by inherited or new mutation of one or both members of a gene pair
The mutation is necessary and sufficient to cause the disease
3 main classes of Mendelian diseases
Autosomal dominant
Autosomal recessive
X-linked
Whats the deal with
1. Expressivity
2. Penetrance
in autosomal dominant diseases?
- Can be variable (age of onset, severity, system involvement)
- Incomplete penetrance may occur (skipped generations)
Penetrance vs expressivity
Penetrance: you have the disease or not
Expressivity: how badly you have the disease/how it appears in you
Genetic vs inherited
Genetic: caused by a difference in a gene/genome
Inherited: transmitted from one or both parents
What factor makes autosomal recessive diseases more likely?
If the parents are related
Clue in the patient history for autosomal recessive
If the patient history is negative
4 examples of autosomal recessive diseases
Cutis Laxa
CF
Sickle cell disease
Thalassemia
Who is affected in X-linked recessive diseases
Only males
“diagonal inheritance”
2 examples of X-linked recessive diseases
Hemophilia
Duchenne’s muscular dystrophy
3 patterns that a new mutation is common for
Autosomal dominant
X linked recessive
Chromosomal abnormalities
- Targeted
- Panel
- Genome-wide
genetic testing
- Looking for mutations of one particular disease
- Testing for mutations of a group of genes associated with a genetically heterogeneous condition
- Testing for disease causing mutations anywhere in the mutation
Suspect genetic disease when… (3)
- Patient has disease that is caused by a genetic mutation
- Family history suggests an inherited condition
- Disease is much more severe or has earlier onset
