weblecture week 3

Question 1

what is intellectural disability?

Answer 1

• IQ level below 70
• limitations in adaptive functioning, self care, managing daily life
• age of onset before 18 years

Question 2

What are the characteristics of intellectual disability?

Answer 2

• clinically and genetically highly heterogeneous
• about 1400 ID genes identified
• some 1000 more to be expected
• high comorbidity of other (cognitive) defects

Question 3

What are the DNA variations in intellectual disability?

Question 4

how much of our DNA is variable?

Answer 4

Around 0,2 % of the 6 billion nucleotides our DNA is build off is variable

Question 5

what is a mutation vs polymorphism?

Answer 5

mutation = low frequency in population < 1%
polymorphism = higher frequency in population > 1%

Question 6

how many private/rare variants are there?

Answer 6

ca. 200 000

Question 7

how many variants are found in exons of genes?

Answer 7

ca. 20 000

Question 8

how many predicted loss-of function variants exist?

Answer 8

ca. 300

Question 9

Where can we find most variations?

Answer 9

on a single nucleotide, i.e. single-nucleotide changes/polymorphism. Also point mutations

Question 10

What are CNVs?

Answer 10

Copy number variances, in the range of 1000 to 100000 base pairs, they can occur even as common variantion in a frequency of ca. 1%. so even 100000 can be a common variation

Question 11

what are the largest variations?

Answer 11

Variations of the size of an entire chromosome, they are very rare and almost by definition give rise to an illness