OCA

Question 1

what is the mutation in OCA1a?

Answer 1

• absent TYR

Question 2

How does OCA1a present?

Answer 2

• generalized and near-complete lack of pigmentation at birth- white hair and skin (hair becomes light yellow over time)

Question 3

What is inheritance of Oculocutaneous albinism?

Answer 3

Autosomal recessive (all subtypes are AR)

Question 4

What is unique about the skin of classic OCA1 patients compared with all other types of OCA?

Answer 4

• they do NOT develop pigmented melanocytic nevi/lentigines/ephelides (all other types do)

Question 5

What is the most common OCA type? Which population is this commonly seen?

Answer 5

OCA type 2

• African americans

Question 6

What are OCA patients at higher risk for with respect to skin?

Answer 6

• BCC

SCC (most common type of skin cancer in these patients)

• melanoma (worse in OCA1)

Question 7

What is the gene mutation in OCA1b?

Answer 7

TRY (decreased)

Question 8

What is the gene mutation in OCA2?

Answer 8

OCA2 gene

Question 9

For OCA1a, 1b and 2, are they tyrosine negative, decreased, or positive?

Answer 9

1a=negative

1b= decreased

2= positive

Question 10

how does OCA2 present?

Answer 10

• variable pigmentary dilution, develop pigmented nevi/lentigines over time, light brown hair and gray/tan irides

Question 11

What is the temperature sensitive variant of OCA?

Answer 11

OCA1b TS: tyrosinase functions at low temperatures, so we see hair pigmentation at cooler anatomic sites like the extremities and white hairs in warmer sites (trunk and intertrigenous areas)

Question 12

Which OCA has worst vision and highest risk of SCC?

Answer 12

OCA1a (this is the one where tyrosinase is absent, so makes sense that it will be most severe presentation)