Genetics Flashcards
what is mendelian disease
one that is controlled by a single locus in an inheritance pattern, a mutation in a single gene that is inherited
Describe ALS in terms of genetics
mutation of SOD1 gene (the gene responsible for controlling excitotoxity)
Amyloid Hypothesis of Alzheimer’s
- Amyloid precursor protein
- gene on chromosome 21
- mutations alter the process and increase production of beta amyloid
- only happens for inheritance in early onset Alzheimer’s
How can a chromosome structure become abnormal
- duplication
- inversion
- deletion
- insertion
- translocation
Describe chromosome aneuploidy
- occurs in >5% of pregnancies
- most often trisomy or occasional monosomy
- can involve all chromosomes but then wouldn’t make it past life
- autosomal triosomes: 21, 13, 18
- monosomy X - there are a number of aneuploidies associated with sex chromosomes
which human characteristics follow Mendel’s first law
- phenylketonuria
- huntington’s disease
- achondroplasia
- cystic fibrosis
- sickle cell disease
What is an example of a sex-linked recessive disorder
Hemophilia B - blood clotting disorder causing easy bruising and bleeding
inherited mutation of gene for factor IX, deficiency of factor IX
What causes x-linked red/green colour blindness
mother to son passing the mutation on the 23rd chromosome
Describe non-mendelian inheritance
- mechanism where inheritance does not follow normal patterns
- e.g. mitochondrial inheritance (faulty energy production) - may cause muscle disorders (parkinson’s)
Describe epigenetics
- inheritance through a change in gene expression without a change in genetic code
Genetics - MND
- SOD1 mutation
- C9orf72 mutation (hexonucleotide repeat in gene of unknown function, expansion of 6 bases)
Genetics - Huntington’s disease
- mutated HTT gene
- Tri nucleotide repeat
- repeat expansions of CAG (codon for glutamine)
- 0ver 60 repeats in early onset
- < 27 repeats = unaffected
- repeat expands through generation (onset gets earlier)
