2 Genetic nomenclature Flashcards
What is a mutation?
○ An intrinsic change in DNA
○ Can be described at
- Chromosomal or
- DNA level
Types of mutation level?
- Genome mutaiton: whole chromosome excess or absence
- Chromosome mutation: chromosome rearrangement (i.e. translocations)
- Gene mutation: mutationi of a single gene
What type of mutation level is a translocation?
It’s a chromosome mutation
What is an allele?
Its 1 of the two copies of a locus
What type of alleles (or alternative copies of a locus can you have?
- Wild type
- The normal version, the prevailing version
- Polymorphism
- “many forms”
- More than one allele is present at a locus within a population
- May lead to disease
- Frequency of >1%
- Mutation
- It’s a permanent change in the nucleotide sequence
- Causes disease
- Rare variant - VOUS
- Allele that does not cause disease VOUS
- Frequency less than 1%
If you find a variant in the human genome, how do you call it if its >1% or <1% of frequency?
- >1% polymorphism
- <1% Rare variant
What are the types of polymorphism?
- SNP
- VNTR - variable number tandem repeats
- STR short tandem repeats
- RFLP restriction fragment length polymorphism
Difference mutation and polymorphism? Main
- Mutation = disease
- Polymorphism= benign mutation
What are “Snips” SNP’s
- Single nucleotide polymorphisms
- It’s a genetic variation among people
- It’s a single NUCLETIDE change a C for T for example
- Occur normally in normal people
- Occur once every 300 nucleotides
- There are 10 million SNPS in the human genome
- Most commonly they are located between genes
- They can act as biological markers or position hints
- If they are within a gene or closer to a gene they can have something to do about causing a disease
- Most SNPs do not cause disease
- They are useful to
- Predict responses to drugs
- Susceptibility to environmental factors
What are the 2 reasons for mutations to occur?
- Spontaneous (DNA replication errors)
- Induced
- By radiation
- Chemicals - mutagenesis
What are examples of diseases causes by advanced maternal and paternal mutations?
- Maternal - down syndrome (cytogenetic)
- Paternal - Achondroplasia (single locus)
What are the prefixes in mutations nomenclature?
- “c” for a coding DNA sequence (c.76A>T)
- “g” for genomic sequence (g.476A>T)
- “m” for a mitochondrial sequence (m.8993T>C)
- “n” for non-coding RNA reference sequence (gene producing an RNA transcript but not a protein)
- “r” for and RNA sequence (r.76a>u)
- “p” for a protein sequence (p.Lys76Asn)
c for
coding DNA sequence (c.76A>T)
“g” for…
for genomic sequence (g.476A>T)
“m” for
mitochondrial sequence (m.8993T>C)