Genetic variation introduction Flashcards
What is found at the end of each arm of a chromosome?
Telomere
What letter is given to the short arm of a chromosome?
P
What letter is given to the long arm of a chromosome?
Q
What is an acrocentric chromosome?
A chromosome that only has a long arm
What is a balanced chromosome rearrangement?
A rearrangement in which all chromosomal material is present
What is an unbalanced chromosome rearrangement?
A rearrangement in which there is missing or extra chromosomal material
What is a aneuploidy?
A condition in which there is a whole extra or missing chromosome
What is a translocation?
The rearrangement of chromosome
What is a microdeletion?
A deletion that is too small to see when karyotyping
What is the medical name for Down’s syndrome?
Trisomy 21
What is the cause of Trisomy 21?
An extra chromosome 21
What is the karyotype of a male with Down’s syndrome?
47XY + 21
What is the medical name for Edward’s syndrome?
Trisomy 18
What is the cause of Trisomy 18?
An extra chromosome 18
What is the karyotype of a male with Edward’s syndrome?
47XY + 18
What is a Robertsonian translocation?
A translocation in which 2 acrocentric chromosomes attach end to end
What is the cause of Turner syndrome (Monosomy X)?
A missing X chromosome in a female
What is the karyotype of a female with Turner syndrome?
45X
What is the karyotype of a female with triple X syndrome?
47XXX
What is the cause of Triple X syndrome?
An extra X chromosome in a female
What is the cause of Klinefelter syndrome?
An extra X chromosome in a male
What is the karyotype of a male with Klinefelter?
47XXY
What is a reciprocal translocation?
A translocation in which a section of one chromosome is swapped with a section of another chromosome
What is array CGH?
A genome wide genetic test that shows the number of a each gene, allowing deletions and insertions to be shown
What is mosaicism?
Different cells have a different genetic constitution
What does Next generation sequencing allow?
Large scale sequencing
What is a mutation/ pathogenic variation?
A genetic variation that causes a disease
What is a polymorphism/ benign variant?
A genetic variation that is prevalent in the population and not, in itself, disease causing
What is the most common base mutation?
From cytosine to thymine
What is a premature stop mutation?
A mutation in which a codon mutates to form a stop codon earlier in the sequence
What is a missense mutation?
A mutation in which one base is mutated into another
What is an insertion mutation?
A mutation in which an extra base is added to the sequence, resulting in a frame shift
What is a deletion mutation?
A mutation in which a base is removed from the sequence, resulting in a frame shift
What is a triplet expansion mutation?
A mutation in which a DNA triplet is replicated
How is a change in base sequence displayed?
c. (base number) (initial base)>(mutated base)
How is a change in protein sequence displayed?
p. (initial amino acid) (amino acid number) (Mutated amino acid)
How is a stop codon displayed in nomenclature?
Ter or *
How is a deletion displayed?
c. (base number) del (base)
How is a frame shift represented in nomenclature?
fs
What is the effect of a change in promotor or splice sequence?
Can stop transcription or cause abnormal splicing
What are the steps of filtering?
Exclude if it is a known polymorphism
Keep if affects gene function (stop, splice)
Is it in a gene that affects phenotype
What is penetrance?
The likelihood of having a disease if you have a gene mutation
What type of inheritance causes blood related disorders and blood types?
Co-dominant inheritance (2 dominant genes)
