genetics

Question 1

three types of genetic conditions:

Answer 1

• rare chromosomal monogenic conditions: down syndrome, cycrtic fibrosis, sickle cell anaemia, haemophilia
• common/complex deficiency: type1 and 2 diabetes, cardiovascular disease, asthma, schizophrenia

non genetic: infection, injury, dietary deficiency.

Question 2

the human genome consists of:

Answer 2

23 pairs of chromosomes;
22 pairs autosomes
1 pair sex chromosome
each diploid cell contains 46 chromosomes

Question 3

the human karotype is:

Answer 3

a karotype is an individuals complete set of chromosomes
consists of 22 pairs of autosomes and 2 sex chromosomes

Question 4

chromosomal banding nomenclature labelled according to:

Answer 4

chromosmal number, then short p or long q, then number out from the centromere.

Question 5

living with trissomy 21 (down syndrome)

Answer 5

learning difficulites
risk of earlty death due to cardiac anomalie
increased risk of leukaemia and alzheimers.

Question 6

procedure of diagnosing down syndrome:

Answer 6

sonogram at 13 weeks.
nuchal translucency- measuring the amount of fluid at the back of fetus neck
blood test measures levels of free beta- HCG and protein PAPP-A
NT measure between 0.25-1.35cm will not have down syndrome
2.2% chance of false positive.

Question 7

further tests for high risk fetus’

Answer 7

• chronic villus sampling - taking a piece of the developing placenta under ultrasound guidance occurs at 11-13 weeks of pregnancy
• amniocentesis - after 15 weeks, removing small amount of amniotic fluid under ultrasound guidance

Question 8

autosomal dominant inheritance

Answer 8

at least one parent is affected
can be transmitted by male and female
male and female can be affected
each child has 50% chance of being affected.

Question 9

autosomal recessive inheritance:

Answer 9

carrier parent usually both unaffected
can be transmitted by male and female and both can be affected
no family history
each child has 25% chance of being affected and 50% chance of being unaffected carrier

Question 10

X-linked recessive:

Answer 10

mutation is on X chromosome, so female isn’t affected
no affected parent
only males affected
each son has 50% chance of being a carrier

Question 11

why do we take genetic family history tests?

Answer 11

to identify genetic disorders
to identify inheritance pattern
for diagnosis
to identify relative risk of disease

Question 12

what are SNPs?

Answer 12

single nucleotide polymorphism
found in DNA between genes
occur 1 in every 1000 base pair in genome.