WEEK 14 (Mutations caused by expandable DNA repeats) Flashcards

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1
Q

What are Trinucleotide repeat sequences?

A

Specific short DNA sequences repeated many times

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2
Q

Describe Fragile X Syndrome

A

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)

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3
Q

Describe Myotonic Dystrophy

A

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

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4
Q

An increased number of trinucleotide repeats will cause what?

A

A more severe form of the disease and an earlier onset of the disease

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5
Q

What is the most common genetic cause of intellectual disability?

A

Down syndrome

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6
Q

What is the most common inherited cause of intellectual disability?

A

Fragile-X Syndrome

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7
Q

Describe Huntington Disease

A

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

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8
Q

Define Anticipation

A

Increased severity or earlier onset of disease in succeeding generations

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