WEEK 14 (Mutations caused by expandable DNA repeats) Flashcards
What are Trinucleotide repeat sequences?
Specific short DNA sequences repeated many times
Describe Fragile X Syndrome
An X-linked dominant inherited disorder which is caused by CGG trinucleotide repeats in FMR1 gene
SYMPTOMS:
- Severe intellectual disability
- Large prominent ears
- Large testes
- Elongated face (Large chin)
Describe Myotonic Dystrophy
An autosomal dominant disorder which is caused by a CTG trinucleotide repeat expansion in the DMPK gene which leads to an abnormal expression of MYOTONIN PROTEIN KINASE leading to MYOTONIA
SYMPTOMS:
- Muscle wasting
- Cataracts
- Frontal balding
- Gonadal atrophy (shrinkage of testes)
- Arrhythmia
An increased number of trinucleotide repeats will cause what?
A more severe form of the disease and an earlier onset of the disease
What is the most common genetic cause of intellectual disability?
Down syndrome
What is the most common inherited cause of intellectual disability?
Fragile-X Syndrome
Describe Huntington Disease
An autosomal dominant trinucleotide disorder caused by CAG trinucleotide repeat expansion in the Huntington gene on chromosome 4; symptoms manifest between ages 20 and 50
SYMPTOMS:
- increased dopamine, decreased GABA & Acetylcholine in brain
- Aggression
- Depression
- Dementia
Define Anticipation
Increased severity or earlier onset of disease in succeeding generations