Genetics

Question 1

Heteroplasmy

Answer 1

Mixture of two types of genetic material– like mitochondrial diseases, 100% of mtDNA comes from the mom but it is distributed randomly to each child, so one child may get more damaged mtDNA and one child may get less –> they both would have the mito disease but one would have way worse symptoms…

SOME EXAMPLES:

• LHON (vision loss)
• Myoclonic epilepsy with ragged red fibers (Myoclonic seizures and myopathy)
• Mitochondrial encephalomyopathy (w/ lactic acidosis & stroke like episodes)

Question 2

Examples of uniparental disomy…

Answer 2

Prader Willi and Angelman syndromes (chromosome 15)

Uniparental disomy= Child gets 2 copies of a chromosome from one parent and none from the other

Prader willi– deleted paternal chromosome 15
Angelman– deleted maternal 15

Question 3

Examples of trinucleotide repeat expansions

Answer 3

Huntington’s (CAG) , fragile X (CGG) , and myotonic dystrophy (CTG)

Question 4

Familial hypercholesterolemia is assoc with this type of mutation—-?

Answer 4

Frameshift mutation

Question 5

The majority of Down syndrome cases arise due to:

Answer 5

Nondisjunction during maternal Meiosis I