GENETIC DISEASES

Question 1

what is the most common cause of birth defects in newborns?

Answer 1

unknown causes (~70%)
- single gene defects 2nd (~20%)

Question 2

how are autosomal chromosomes ordered?

Answer 2

decreasing size
- chromosome 1= LARGEST
- chromosome 22= smallest

Question 3

cytogenic disorders

Answer 3

disorders caused by the change in NUMBER or STRUCTURE of chromosomes
- may affect either autosomal or sex chromosomes

Question 4

Numeric chromosomal changes

Answer 4

change in the number of chromosomes
- disease examples: Trisomy 21 (Down Syndrome,)

Question 5

mosaicism

Answer 5

presence of 2 or more cell lines within an individual
- leads to a mix of cells with different genetic material

Question 6

Structural chromosomal changes

Answer 6

physical errors in the chromosome
- translocation, deletion, inversion, ring chromosome

Question 7

nondisjunction

Answer 7

failure of chromosomes to separate during cell division
- if occurs in meiosis 1–> gametes with n+1, n+1, n-1, n-1
- if occurs in meiosis 2–> 50% of normal gametes n+1, n-1, n,n

Question 8

isochromosome

Answer 8

result of a mutation of chromosome at the centromere, resulting in an abnormal chromosome being a mirror image of itself

Question 9

inversions

Answer 9

chromosomal mutations that occur when there are two breaks in a chromosome that is re-ligated in the opposite direction
- results in an error in the reading frame
- paracentric vs pericentric

Question 10

ring chromosomes

Answer 10

loss of terminal ends of chromosomes, resulting in the ends fusing together to form a ring

Question 11

karyotyping

Answer 11

lab technique to examine number, size and shape
- stains chromosomes in a way that allows you to see the large scale abnormalities/changes in chromosomes