GENETICS - Mutations and Defects Flashcards
Red-Green defects are in which disease?
acquired optic nerve disease (except glaucoma and autosomal dominant optic atrophy)
What are the main examples of trinucleotide repeat disorders? (7)
- Fragile X syndrome
- Friedrich’s ataxia
- Machado-Joseph ataxia
- Spinocerebellar ataxia
- Spinobulbar muscular atrophy
- Myotonic dystrophy
- Huntington chorea
Blue-yellow defects are in which disease
Acquired retina disease (except cone dystrophy and Stargardt’s)
What are the X-linked dominant conditions? (3)
- Aicardi syndrome
- Incontinentia pigmentii
- Alport’s syndrome
Which chromosome defect is associated with retinoblastoma?
Rb gene located on long arm chromosome 13
What diseases are examples of mitrochondrial inheritance? (6)
- Lebers hereditary optic atrophy
- Mitochondrial encephalopathy, lactic acidosis and stroke (MELAS)
- Myoclonus epilepsy associated with ragged-red fibres (MERRF)
- Kearns-Sayre syndrome (KSS)
- Pearson syndrome
- Diabetes/Deafness
Which mutations causes MEN 2a and MEN2b?
RET proto-oncogene on chromosome 10
What is a mutation? What external factors can cause a mutation?
any permanent change in DNA
1) Ionising radiation
2) Chemicals
3) UV light
What are the three types of point mutations?
1 - missense mutation - different amino acids are transcribed altering the sense of the code (haemoglobinopathies
2 - nonsense mutation - mutation leads to premature stop codon - NF type 1
3 - splice mutation - mutation alters a critical splice junction
What examples are there for triplet expansion diseases? (4)
- myotonic dystrophy
- Fragile-X
- Huntington’s
- Spinocerebellar ataxia
What examples are there of microdeletion syndromes? (4)
- Prader Willi
- Williams syndrome
- Di George
- Rubinstein Taybi
Consanguinity is more likely to have which type of inheritance?
Recessive
What is a Robertsonian translocation?
a chromosome rearrangement where the two long arms of two acrocentric chromosomes (non central centromeres) fuse to form a single chromosome
How many chromosomes do robertsonian individuals have? what is their risk of trisomy in offspring?
- 45 chromosomes (normal phenotype)
- increased risk
What is lyonisation? What does it give rise to in terms of expression?
Lyonisation is a physiological process where one of the two X chromosomes in cells of a female is inactivated during embryonic development (male/female X chromosome is randomly affected).
gives rise to patchy expression of X-linked mutations in female carriers
