Transmission of genetic disease Flashcards
What are the two types of inheritable disease?
Monogenetic: Clear inheritance, not environmentally effected
Complex disorders: no clear inheritance, effected by environment and common
What are alleles?
Different forms of a gene at the same locus
What are homologous chromosomes?
Matching pair of chromosomes inherited from each parent
What is a polymorphism?
Mutation present in >1% of population
What are the types of mutation?
Point mutation
Insertion/deletion - leading to frameshift
What are the two types of point mutation?
Missense: Incorrect amino acid coded
Nonsense: Stop codon coded
What is the risk of an affected child with an Autosomal Dominant condition?
50-75%
What increases the risk of Autosomal recessive gene expression?
Consanguinity:
closely related individuals who reproduce can increase likelihood of recessive conditions in children
Give an example of an Autosomal dominant disease
Huntington’s
Give an example of an Autosomal Recessive disease:
Cystic Fibrosis: chronic, life-limiting condition leading to excess mucus production in lungs and pancreas, causing breathing difficulties and stunted growth (CFTR gene mutation leads to mutated form of chloride ion channel in epithelial cells) - 1500 mutations identified and CF testing included in UK newborn screening programme
Give an example of an X-linked recessive disease:
Haemophilia
What is Genetic Heterogeneity?
Same gene with different mutations causing different symptoms.
Same disease, different genes/inheritance patterns
Give an example of Genetic heterogeneity:
Congenital absence of vas deferens also caused by CFTR mutation
What is it called when symptoms are not always present in an individual w/disease-causing mutation?
Incomplete penetrance
What is Variable expressivity?
Severity of disease differs between people w/same disease-causing mutation
