2 - Risk of transmission of disease Flashcards
What are the types of genetic disease?
Give an example of each
monogenic e.g. Huntington’s, CF, Haemophilia
complex disorders e.g. Type 2 diabetes, schizophrenia, Crohn’s disease
What are point mutations?
a single change in the DNA sequence
What are the 2 types of point mutations?
missense and nonsense
What are missense mutations?
mutations that result in a different amino acid being coded for
What are nonsense mutations?
mutations that result in the STOP codon, so the polypeptide chain ends prematurely
What are the 2 types of frameshift mutations?
insertions and deletions
sometimes referred to as InDel
When drawing pedigrees, what is the symbol if the sex is unknown?
a diamond
How are the deceased represented on pedigree diagrams?
diagonal line through square/circle/diamond
How are pregnant people represented on pedigree diagrams?
a P in the centre of the shape
On pedigree diagrams, how is the person providing the information highlighted?
with an arrow towards the bottom the the shape
Who is affected by X-linked recessive conditions?
Who is a carrier of these conditions?
Give an example of an X-linked recessive condition?
usually only males
females
e.g. haemophilia
How can haemophilia be treated?
with injections of clotting factor
What are the similarities and differences between haemophilia A and B in terms of symptoms?
symptoms are identical in both
haemophilia B is much rarer
Genetic heterogeneity: give an examples of 2 diseases with the same gene different mutation different symptoms
Cystic fibrosis and CAVD
Genetic heterogeneity:
give an examples of 2 diseases with
the same disease
different genes
Haemophilia A and B
Genetic heterogeneity: give an examples of 2 diseases with the same disease different genes different inheritance patterns
different forms of epidermolysis bullosa
Define pentrance
the proportion of individuals with the disease-causing mutations (the genotype) that also express the associated symptoms (the phenotype)
Define (variable) expressivity
disease severity may vary between individuals with the same disease-causing mutation
Define phencopy
having the same disease, but with a different underlying cause
e.g. obesity
Define epistasis
interactions between disease gene mutations and other modifier genes can affect the phenotype
e.g. severity of CF
a type of gene action where one gene can suppress the action of another (nonallelic) gene
