Flashcards in Mendelian Inheritance Deck (13):
what are 2 examples of autosomal dominant diseases
huntington disease and familial forms of breast cancer
what are 2 examples of autosomal recessive diseases
cystic fibrosis, gaucher disease, peroxisome biogenesis disorders
what was the x linked dominate syndrome covered in lecture?
Rett Syndrome caused by MECP2
Males with severe MECP2 are not born
progressive neurodevelopment disease
what is an example of x linked recessive disease?
duchenne and becker muscular dystrophy
huntington disease is what type of disease caused by what?
neurodegenerative disorder caused y CAG repeats in the HTT gene
name 3 peroxisome disorders
zellweger synder (ZS), neonatal adrenoleukodystrophy (NALD), infantile refsum disease (IRD)
what is zellweger disorders caused by
mutations in any of 13 PEX
occurs in more than one region
brca1 brca2 dominant or recessive?
when one gene influences multiple phenotypic trait
Peroxisome biogenesis disorders (PBDs) illustrate some key concepts in inheritance. PBDs result when both copies of a given PEX gene responsible for peroxisome assembly have compromised activity. Patients with similar clinical phenotypes can have different PEX genes inactivated (locus heterogeneity). Thus, genetic tests often need to screen multiple PEX genes to identify the single PEX gene that is mutated (both copies) in patients. Most of the time the patients have compound heterozygous mutations (mutations in the same PEX gene, but different inactivating mutations). PBDs show pleiotrophy since multiple clinical phenotypes are observed. There is variable expressivity since some patients are more severely affected by disease than others. This is demonstrated by the subtypes of diseases comprising the Zellweger Spectrum Disorder.
Penetrance and variable expressivity often get confused. Penetrance is an all-or-none phenomenon, i.e. does a person have the disease or not while still carrying the mutation; variable expressivity assumes the person has the symptoms and refers to the variability in the extent to which the person is affected
5 factors that determine H-W equilibrium
1. based on random dating 2. based on normal mutation rate 3. no selection 4. large population 5. limited influx of new genetic varation