Neurogenetics

Question 1

Define penetrance

Answer 1

probability that a person carrying a gene will develop the disease

Question 2

Define expresivity

Answer 2

Extent to which a gene is expressed in one person

Question 3

Define anticipation

Answer 3

The tendency of some variable dominant conditions to become more severe or occur earlier in successive generations
- due to unstable expanding trinucleotide repeats prone to errors during cell division

Question 4

Define X-inactivation

Answer 4

Inactivation of X chromosomes in women to ensure women and men have same number of active X chromosome genes

Question 5

Define genomic imprinting

Answer 5

Identical genes differ in expression depending on parental origin.
- imprint due to different methylation during meiosis and gametogenesis

Question 6

Deinfe uniparental disomy

Answer 6

Both chromosomes of a pair originate from one parent
- rescued disomy

Would cause problems if gene is imprinted

Question 7

Give examples of autosomal dominant conditions

Answer 7

Huntington’s

Neurofibromatosis

Tuberous sclerosis

HMSN 1

Von Hippel Lindau

Question 8

Give examples of some autosomal recessive conditions

Answer 8

Tay Sachs

Neuronal Ceroid Lipofuscinoses

Mucopolysaccharides

Question 9

Give examples of some X-linked conditions

Answer 9

Duchenne Muscular Dystrophy

Becker MD

Fragile X Syndrome

Question 10

Give examples of some Mitochondrial diseases

Answer 10

Leber’s hereditary optic neuropathy

Kearn’s Sayre Syndrome

Mitochondrial Encephalomeylopathy Ragged Red fibres

Mitochondrial Encephalomeylopathy Lactic Acidosis Stroke like Episodes

Question 11

What are diseases of Multifactoral inheritance

Answer 11

The combined contribution of one or more often unspecified genes and environmental factors in the causation of a particular trait or disease
- often unknown