Dominant/ressesive/x linked/chromosomal disorders

Question 1

What are the autosomal dominant disorders

Answer 1

1. Huningtons disease
2. Marfan syndrome
3. Polycystic kidney disease
4. Charcoat marie tooth disease

Question 2

What happens in huningtons disease, S+S

Answer 2

Insertion mutation of CAG repeats (>36 repeats)
affecting basal ganglia + Gaba receptors

s+s= onset @ 40, cognitive decline, jerky mvmts

Question 3

What happens in marfan syndrome, S+S

Answer 3

missense mutation in fibrillin gene

-Fibrillin essential for ECM so will have weak + disorganized connective tissue

Question 4

what happens in polycystic kidney disease, S+S

Answer 4

Mutation in PKD1 or PDK2 gene
-leads to proliferation of epithelium forming fluid filled sacs
s+s= hypertension, flank/back pain, blood in urine

Question 5

What happens in charcoat marie-tooth disease

Answer 5

Mutation in PMP22 gene which codes for myelin
-leads to demylenation + slowing of peripheral nerve conduction

s+s= sensory impairment, foot drop, stork leg

Question 6

What are the autosomal recessive disorders

Answer 6

Cystic fibrosis

Sickle cell amenia

Question 7

What happens in cystic fibrosis

Answer 7

Deletion in CFTR gene

-cant secrete cl- to outside so cuases thick mucus

Question 8

What happens in sickle cell amenia ( and what is the less severe version)

Answer 8

Missense in B globin in hemoglobin (in pos. 6)
Results in ridgid, sickle shapped RBCs

S+S= fatigue, Crisis, Edema, Risk of Stroke

Heterozygotes show resistence to malaria

Question 9

What are the x linked disorders

Answer 9

Rett syndrome
Red/Green color blindness
Hemophilia
Muscular dystrophy

Question 10

What is lyonization

Answer 10

Only one allele expressed per gene

Question 11

What is rett syndrome (what is affected and what does it cause + what unique thing does it show)

Answer 11

• Most males die (100% penetrance)
• MeCP2 affected which causes neuronal dysfunction

Shows skewed x inactiavtion- When an alle is on just one x gene it actually has 80% chance of being expressed

Question 12

Dichromy and types

Answer 12

Can see blue but not red or green

protaropia- no red
Duoterunpia- no green

Question 13

what is anomalous trichromy

Answer 13

Defective in red or green

Question 14

What causes hemophilia

Answer 14

Mutation in F8 gene causing inability to clot

Question 15

Difference bw duchanes and beckers muscle dystrophy

Answer 15

w/o dystrophin cytoskeleton not connected to muscle fibre (which ends up destroying mm fibre)

Duchances- no dystrophan made
Beckers- mishappen dystrophan (later onset)

Question 16

What are the chromasomal disorders

Answer 16

1. Down syndrome
2. Klinfelter syndrome
3. Turner syndrome

Question 17

Types of down syndrome

Answer 17

1. trisomy of 21- Extra copy of 21 (due to maternal dysjunction)
2. Roberson translocation- long piece of 21 breaks off and attaches to 14

Question 18

What is klinefeller syndrome due to

Answer 18

Nondysjunction on sex chromosome causeing 47xxy

-male sex organs, less body weight, taller etc

Question 19

What is turner sysndrome

Answer 19

45x in females

Shorter stature, infertility, heart defects