Genetics Flashcards
What are some of the symptoms of pompe’s disease?
Respiratory muscle weakness; can cause headaches, tiredness, disturbed sleep.
Proximal muscle weakness;
Pelvic girdle weakness can cause difficulty getting up stairs and chairs.
Shoulder girdle muscle weakness can cause difficulty reaching or lifting things, and washing/brushing hair.
What is the cause of pomp’s disease?
It is a rare glycogen storage disease. caused by the lack of an enzyme which breaks down glycogen in lysosomes.
Leads to the accumulation of glycogen in lysosomes and the the accumulation of lysosomes in cells.
It is an autosomal recessive condition.
What are the treatments available for pomp’s disease?
Non-invasive ventilation, provides positive pressure.
Enzyme replacement therapy.
What are the three forms of Pompe’s disease?
Infantile, childhood, adult-onset
What enzyme breaks down glycogen in lysosomes?
Acid maltase.
What drug is given in enzyme replacement therapy for Pompe’s disease?
Myozyme - an analogue of the enzyme acid maltase.
What is the sign for a wild type (normal) allele and an abnormal allele?
Wild type: +
Abnormal: -
Definition of an allele?
specific DNA sequence or copy of a gene
What are the features of an autosomal dominant condition, what would mean that it had to be an autosomal dominant condition?
Affects males and females, Transmitted by males and females.
If there is a direct male to male transmission it must be autosomal dominant.
How many chromosomes in a normal human cell?
46 - 23 pairs
What is a numerical chromosome abnormality?
Too many or too few chromosomes.
3 most common autosomal chromosome abnormalities?
Trisomy 21 - Downs
Trisomy 18 - Edwards syndrome
Trisomy 13 - Patau syndrome
Common features of numerical chromosome abnormalities?
Increase in frequency with maternal age
Occur most commonly at female meiosis
Parental chromosomes are usually normal.
What are the different types of structural chromosome abnormality?
Unbalanced
Balanced:Normal
Balanced:Carrier
Types of base pair mutations?
Single Base Pair mutations:
- Missense: Replace one Amino acid for another
- Nonsense: replace one amino acid for a STOP codon
Splice site mutation - change in signals for intron-exon splicing.
Frame shift mutation.
What does mitochondrial dna code for?
Components of the oxidative phosphorylation system.
Where do you inherit your mitochondrial DNA from?
Exclusively from your mother.
What is anticipation, in genetic conditions?
Trinucleotide repeats causing disease, get’s worse in subsequent generations.
What is Mosaicism, in genetic conditions?
When there are two cell populations, one which is affected and one which isn’t, expressed in different parts of the body.
What is Allelic heterogeneity and Locus homogeneity?
Locus; Mutation in different genes that cause the same phenotype
Allelic: Different changes at the same Locus.
Protocol for doing a Huntingtons gene test?
See 3 times first
Discuss what the result will mean
Await till they are 18 yrs Old?
Why does allelic heterogeneity cause a problem in genetic tests?
Can cause a high number of false negatives, it is hard to know that you have not missed a gene.
An example of allelic heterogeneity?
Retinitis pigmentosa
What is X inactivation?
The fact that one X chromosome in a female cell is ‘inactivated’ so genes from only one chromosome are expressed.
