CHAP 4 Flashcards
What were Mendel’s two central principles?
- Principle of segregation
2. Principle of independent assortment
CF is caused by mutation of what gene?
CFTR, which encodes cyclic AMP-regulated chloride ion channels
What is a proband?
the first person who the disease is diagnosed in a pedigree AKA index case or propositus
What is a vertical transmission pattern?
Diseased phenotype is seen in one generation after another
What is the significance of a father to son transmission?
It rules out that the disease is X-linked
What is recurrence risk?
the probability that an individual offspring will be affected by disese
Albinism is caused by a mutation in the gene that encodes for what enzyme
tyrodinase which blocks the metabolic pathway to create melanin (AUTOSOME RECESSIVE)
Quasidominant inheritance
When a homozygous and heterozygous of a recessive autosomal disease mate, it mimics the inheriting pattern of a dominant disease (recurrance risk is 50%)
What is de novo mutation?
Unaffected parent’s allele underwent a DNA change resulting in a disease.
What is germline mosaicism?
When there is a present of one or more genetically distinct cell line
What is an example of a disease that exhibits age-dependent penetrance
Huntington’s Disease
What three factors contribute to variable expression?
modifier loci, allelic heterogeneity, environmental factors
What is locus heterogeneity?
a single disease phenotype is caused by mutations at different loci in different families
What is a pleiotropic gene?
a gene that has more than one discernible effect on the body (Marfan Syndrome -FBN1)
What does the coefficient of relation determine?
The percentage of genes shared by a pair of relatives
