Neurogenetics

Question 1

What is the definition of penetrance?

Answer 1

Probability that a person carrying a gene will develop the disease

Question 2

What is the definition of expressivity?

Answer 2

Extent to which a gene is expressed in one person

Question 3

What is the definition of anticipation?

Answer 3

Tendency of some variable dominant conditions to become more severe or occur earlier in successive generations. Due to unstable expanding trinucleotide (triplet) repeats prone to errors during cell division.

Question 4

What is the definition of X inactivation?

Answer 4

Inactivation of one X chromosome in women to ensure that men and women have the same number of active X chromosome genes (lyonisation)

Question 5

What is the definition of genomic imprinting?

Answer 5

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

Question 6

What is the definition of uniparental disomy?

Answer 6

Both chromosomes of a pair originate from one parent. (Rescued trisomy). Causes a problem when gene is imprinted.

Question 7

What is multifactorial inheritance?

Answer 7

Combined contribution of one or more often unspecified genes and environmental factors, often unknown, in the causation of a particular trait or disease (predisposition).

Single nucleotide polymorphism

• Most common type of genetic variation
• common but mostly outside of coding sequence = exome
• affects how we respond to external factors

Copy number variation

• Number of genes varies from individual to individual