OculoCutaneous Albinism

Question 1

Mode of inheritance in OCA ??

Answer 1

AR
Rare> AD

Question 2

How many types in OCA ?

Answer 2

7

Question 3

Mutation in OCA 1 ??

Answer 3

OCA1A (absent tyrosinase) tyr gene
OCA1B (decreased tyrosinase) tyr gene

Question 4

Mutation in OCA2 ?

Answer 4

P gene (pink eye dilution)

Question 5

Fxn of P gene ??

Answer 5

Regulates organelle pH and accumulation of glutathione

Question 6

Mutation in OCA3 ?

Answer 6

TYRP1

Question 7

Abbreviation of TYRP ?

Answer 7

Tyrosinase related protein

Question 8

Fxn of TYRP ?

Answer 8

Stabilizes tyrosinase in eumelanin synthesis

Question 9

Which types there is abnormal protein in ER ??

Answer 9

Type 1 and 3

Question 10

Mutation in OCA4 ?

Answer 10

SLC 45A2

Question 11

Mutation in OCA5?

Answer 11

Unknown but located on chromosome 4

Question 12

Mutation in OCA6 ??

Answer 12

SLC24A5

Question 13

Fxn of SLC24A5 ?

Answer 13

Cation exchanger in melanosome membrane

Question 14

Mutation in OCA 7 ?

Answer 14

C10 orf11on q10

Question 15

Most common mode of inheritance form of OCA IS??

Answer 15

X-linked recessive

Question 16

Most common mutation in OCA ?

Answer 16

G protein coupled receptor

Question 17

Gene mutation in Ocular albinism??

Answer 17

GPR 143

Question 18

Pathophysiology of ocular albinism ?

Answer 18

Misrouting of optic nerve fibers

Question 19

Symptoms of ocular albinism?

Answer 19

1- reduced visual acquity
2- photophobia
3- strabismus
4- nystagmus
5- lack binocular vision

Question 20

Eye structures involved in ocular albinism?

Answer 20

Retina
Fovea

Question 21

Which type of OCA has most severe ocular dysfunction?

Answer 21

OCA1A

Question 22

What is tyrosinase negative OCA ?

Answer 22

OCA1A

Question 23

Symptoms of OCA1A ?

Answer 23

Milky white skin + blue_grey eyes + white hair +amelanotic melanocytic nevi

Question 24

In OCA1A the hair becomes yellow with time?

Answer 24

Due to the denaturing of hair keratins 

Question 25

Other names of OCA1B ?

Answer 25

Yellow albinism, platinum OCA, temperature sensitive OCA

BECAUSE OF LESS TYROSINE IS REQUIRED FOR PHEOMELANIN FORMATION > born with yellow hair

Question 26

Forms of OCA1B ?

Answer 26

1- temperature sensitive
2- minimal pigment OCA

Question 27

Nevi in OCA1B

Answer 27

Pigmented or amelanotic

Question 28

Describe temperature sensitive OCA1B?

Answer 28

Ptn is born whith white hair and blue eyes,
After puberty they have :: red brown arm hair and dark brown leg hair .
Scalp and axillary hair remain white

Question 29

What causes temperature sensitive OCA1B ?

Answer 29

Abnormal tyrosine become dysfunctional at temperature above 35