Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

MK ACVD Exam > Melanogenesis and melanocytic disorders > Flashcards

Melanogenesis and melanocytic disorders Flashcards

1
Q

What gene mutations have been associated with piebaldism?

A

c-kit/CD117
steel factor

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
1
Q

What genes are mutated in Waardenburg-Klein syndrome?

A

EDNRB
MITF
SOX10
PAX3

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

What is the inheritance pattern of Waardenburg-Klein syndrome?

A

Autosomal dominant

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

What is the inheritance pattern of lentiginosis profusa?

A

Autosomal dominant

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

What breed is predisposed to lentiginosis profusa?

A

Pugs

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

What is the inheritance pattern of piebaldism?

A

Autosomal dominant

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

What breed of cat is affected by Chediak-Higashi syndrome?

A

Persian (blue smoke color only)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

What is the inheritance pattern of Chediak-Higashi syndrome in cats?

A

Autosomal recessive

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

What gene is mutated in Chediak-Higashi syndrome in cats?

A

LYST

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

What is the inheritance pattern of color dilution alopecia?

A

Autosomal recessive

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

What gene is mutated in color dilution alopecia?

A

MLPH

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

What is the inheritance pattern of vitiligo?

A

Autosomal recessive

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

What gene is mutated in vitiligo?

A

FOXD3

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

What is the inheritance pattern of feline acromelanism?

A

Autosomal recessive

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

What gene is mutated in feline acromelanism?

A

tyrosinase OCA1B

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

From what structure are melanocytes derived?

A

Neural crest

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

Besides the skin, where else are melanocytes found?

A

Meninges
Cochlea (stria vascularis)
Eyes

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

What determines color in amphibians, fish, reptiles, and crustaceans?

A

Chromatophores

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

What determines color in mammals and birds?

A

Melanin

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

How many melanocytes comprise an epidermal melanin unit in dogs?

A

1 melanocyte per 10-20 KCs

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

What IHC markers are used for melanocytes?

A

Vimentin
S-100 protein

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

What type of melanin is red-yellow?

A

Pheomelanin

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

What type of melanin is brown-black?

A

Eumelanin

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

What type of melanin has spherical melanosomes?

A

Pheomelanin

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
Q

What type of melanin has elliptical melanosomes?

A

Eumelanin

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
25
Q

What type of melanin is low in cysteine?

A

Eumelanin

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
26
Q

What type of melanin is high in cysteine?

A

Pheomelanin

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
27
Q

What type of melanin is produced in high levels of tyrosinase?

A

Eumelanin

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
28
Q

What type of melanin is produced in low levels of tyrosinase?

A

Pheomelanin

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
29
Q

What type of melanin is high in sulfur?

A

Pheomelanin

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
30
Q

What enzyme converts tyrosine to DOPA?

A

tyrosinase

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
31
Q

What serves as a critical co-factor in melanogenesis?

A

copper

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
32
Q

What is the rate limiting step in melanogenesis?

A

Conversion of tyrosine to DOPA via tyrosinase

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
33
Q

What protein serves as a specific marker for melanocytes?

A

Tyrosinase

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
34
Q

What hormone is the main driver of melanogenesis?

A

alpha-MSH (melanocyte stimulating hormone)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
35
Q

What receptor does alpha-MSH act on to activate melanogenesis?

A

MC1-R

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
36
Q

What cytokine does alpha-MSH antagonize?

A

IL-1

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
37
Q

What protein inhibits the differentiation of neural crest cells into melanocytes?

A

BMP-4

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
38
Q

What cytokines act as inhibitors of melanogenesis?

A

TNF-a
IL-1
IL-6

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
39
Q

During which phase of the hair cycle are melanosomes transferred to hair shafts?

A

Anagen only

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
40
Q

What is the mutation in Waardenburg syndrome type IV?

A

EDNRB

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
41
Q

What is the mutation in lethal white foal syndrome and what is the mode of inheritance?

A

EDNRB
Autosomal recessive

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
42
Q

What condition is responsible for the “blaze” pattern and deafness seen in many pet store ferrets?

A

Waardenburg syndrome

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
43
Q

A gray-blue Persian is presented with yellow eyes and a red light reflection on fundic exam. What mutation is responsible for this?

A

LYST gene mutation (causing Chediak-Higashi syndrome)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
44
Q

What breed is affected by lethal lavender foal syndrome?

A

Arabians of Egyptian descent

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
45
Q

What gene is mutated in lethal lavender foal syndrome?

A

MYO5A (affects melanosome transfer to KCs)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
46
Q

What breeds are predisposed to color dilution alopecia?

A

Great Danes
Dobermans
Dachshunds
Whippets
Italian Greyhounds

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
47
Q

What is the most common type of acquired hyperpigmentation?

A

Post-inflammatory hyperpigmentation

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
48
Q

At which temperature does tyrosinase OCA1B become inactive?

A

above 35degC

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
49
Q

Inhibition of the MC1R gene would result in production of which melanin?

A

Pheomelanin

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
50
Q

Activation of the MC1R gene would result in production of which melanin?

A

Eumelanin

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
51
Q

What controls the shade of eumelanin that is produced?

A

TYRP1

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
52
Q

Why does piebaldism tend to affect midline areas (forehead, chest, abdomen)?

A

These areas are the furthest for melanocytes to migrate

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
53
Q

True or false: deafness and hypopigmented irises are clinical features of piebaldism in dogs

A

False

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
54
Q

What is mutated in short-horned and Belgian blue cattle to cause the roan coat color?

A

KIT-ligand (aka stem cell factor)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
55
Q

What condition is characterized by white coat color and congenital sensorineural deafness?

A

Waardenburg syndrome type 2

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
56
Q

What genes have been associated with mutations causing Waardenburg syndrome type 2 in dogs?

A

MITF
SILV

57
Q

What genes have been associated with mutations causing Waardenburg syndrome type 2 in cats?

A

KIT

58
Q

What genes have been associated with mutations causing Waardenburg syndrome type 2 in cattle?

A

MITF

59
Q

What genes have been associated with mutations causing Waardenburg syndrome type 2 in pigs?

A

MITF

60
Q

What genes have been associated with mutations causing Waardenburg syndrome type 2 in horses?

A

EDNRB
PAX3
MITF

61
Q

What breed of horse has a mutation in EDNRB that causes Waardenburg syndrome type 2?

A

Paint

62
Q

Why are animals with Waardenburg syndrome also usually deaf?

A

Failure of melanocytes to migrate normally to stria vascularis –> hypoplastic cochlea –> failure to recycle K+ for action potential –> less endolymph production

63
Q

What interaction between melanocytes and KCs controls migration of melanocytes to the anagen hair bulb?

A

KIT and KIT-ligand (Steel factor)

64
Q

What signals are responsible for keeping melanocyte stem cells inactive during telogen?

A

TGF-B
Notch

65
Q

Why does Palladia result in hair graying?

A

It is a KIT inhibitor –> melanocyte stem cells do not migrate to anagen hair bulb

66
Q

What is the inheritance pattern of the gray horse phenotype?

A

Autosomal dominant

67
Q

What gene is mutated in the gray horse phenotype?

A

STX17

68
Q

What stages of melanosome formation involve melanin?

A

Stages III and IV (stages I+II melanin-free)

69
Q

What gene is mutated in Gray Collie Syndrome?

A

AP3B1

70
Q

What is Gray Collie syndrome also known as?

A

Canine cyclical hematopoiesis

71
Q

What coat phenotype is associated with Germansky-Pudlak syndrome type 3 in Frenchies?

A

Cocoa coat

72
Q

Besides coat color, what abnormality is seen in Frenchies with Hemansky-Pudlak syndrome type 3?

A

Decreased platelet dense granules (though normal bleeding)

73
Q

A silver-coated cat is presented with large granules within the cytoplasm of neutrophils. What gene is affected?

A

LYST (Chediak-Higashi syndrome)

74
Q

What gene mutation is associated with the merle coat phenotype in dogs?

A

SILV

75
Q

What gene is mutated in the Harlequin phenotype in Great Danes?

A

PSMB7

76
Q

What are the two components of eumelanin?

A

DHI (5,6-dihydroxyindole)
DHICA (5,6-dihydroxyindole-2-carboxylic acid)

77
Q

What is pheomelanin composed of?

A

Benzothiazine units

78
Q

How is L-tyrosine obtained?

A

From the diet
From conversion of phenylalanine

79
Q

Describe the melanogenesis pathway that is shared between eumelanin and pheomelanin

A

L-tyrosine–> L-dopa–> dopaquinone

80
Q

How is dopaquinone converted into dopachrome?

A

It is converted spontaneously

81
Q

What enzyme is responsible for the conversion of dopachrome into DHICA and what type of melanin is subsequently produced?

A

dopachrome tautomerase/TYRP2
Eumelanin produced

82
Q

What is dopachrome converted into?

A

5,6-dihydroxyindole (DHI) and DHICA

83
Q

What needs to be present in sufficient amounts in order for pheomelanin to be produced?

A

Cysteine or glutathione

84
Q

What are the 3 enzymes involved in the production of eumelanin from L-tyrosine?

A

Tyrosinase
TYRP1
TYRP2

85
Q

What is dopaquinone converted to in the presence of cysteine or glutathione?

A

cysteinylDOPA

86
Q

What is the role of tyrosinase or TYRP1 late in the eumelanin pathway?

A

It converts DHICA into eumelanin

87
Q

What is the pathogenesis of oculocutaneous albinism?

A

Lack of melanin synthesis in melanosomes

88
Q

Are animals with oculocutaneous albinism deaf?

A

No–melanocytes are present but there is a lack of melanin synthesis (present melanocytes=unaffected hearing)

89
Q

What types of oculocutaneous albinism are present in animals?

A

Types I-IV

90
Q

What gene is mutated in oculocutaneous albinism type IV?

A

SCL45A2

91
Q

What gene mutation is associated with cream and white coat colors in dogs and horses?

A

SLC45A2 (analogous to oculocutaneous albinism type IV)

92
Q

What gene mutation causes a dilution in pheomelanin but not eumelanin?

A

MFSD12

93
Q

What amino acids are likely lacking in the diet in a black cat whose coat turns red-brown?

A

Tyrosine or phenylalanine

94
Q

What dietary deficiency would lead to graying of the coat?

A

Copper

95
Q

What is the pigmentary synapse?

A

melanosome transfer to KCs at the tips of melanocyte dendrites

96
Q

Which proteins present at the tips of melanocyte dendrites facilitate melanosome transfer?

A

Rab27a
Melanophilin
Myosin-5a

97
Q

Where are the primary locations of melanocytes in the skin?

A

Epidermis
Hair follicle

98
Q

What layer of the skin houses the most melanocytes?

A

Basal layer of epidermis

99
Q

What serves as the prime mediator of adhesion between melanocytes and keratinocytes?

A

E-cadherin

100
Q

What special stain would highligh melanocytes?

A

Fontana-Masson

101
Q

What is the key intermediate in the melanin synthesis pathway?

A

Dopaquinone

102
Q

What transcription factor serves as the primary regulator of melanogenesis?

A

MITF

103
Q

What is the role of Wnt in melanogenesis?

A

Promotes differentiation of melanoblasts into melanocytes

104
Q

What protein serves as a precursor for alpha-MSH and where is the precursor protein produced?

A

POMC
Produced by pituitary gland

105
Q

How does UVR increase skin pigmentation?

A

Increases POMC gene expression –> cleaved into alpha-MSH –> alpha-MSH binds to MC1R –> increased cAMP –> increased MITF –> increased melanogenesis

106
Q

What is the effect of nitric oxide on melanogenesis?

A

Stimulatory

107
Q

What is the effect of ACTH on melanogensis?

A

Stimulatory

108
Q

What is the effect of steel factor on melanogensis?

A

Stimulatory

109
Q

What is the effect of PGE2 on melanogenesis?

A

Stimulatory

110
Q

What is the effect of histamine on melanogensis?

A

Stimulatory

111
Q

What is the effect of TNF-a on melanogenesis?

A

Inhibitory

111
Q

What is the effect of IL-1 on melanogenesis?

A

Inhibitory

112
Q

What is the effect of IL-6 on melanogenesis?

A

Inhibitory

113
Q

What is the role of BMP-4 in melanogenesis?

A

Inhibits differentiation of neural crest cells into melanocytes

114
Q

What family of peptides is important for the migration of melanoblasts from dermis to basal layer of epidermis?

A

Endothelin family

115
Q

What receptor is present on melanoblasts and interacts with endothelin-3 to allow for normal proliferation and migration of melanoblasts?

A

endothelin receptor B (EDNRB)

116
Q

Besides resulting in abnormal melanocyte formation, what else will fail to form if there is a faulty interaction between EDNRB and ET3?

A

Enteric nerves

117
Q

What proteins help transport melanosomes along the dendrites of melanocytes?

A

Dyneins
Kinesins

118
Q

What protein plays a role in actin binding and melanosome transfer once the melanosome has reached the tip of the dendrite?

A

Myosin-5a

119
Q

Are melanosomes larger in follicular melanocytes or in epidermal melanosomes?

A

Follicular

120
Q

Are follicular or epidermal melanocytes larger?

A

Follicular

121
Q

In what part of the follicle are melanocytes located during anagen?

A

Proximal hair bulb

122
Q

What happens to melanocytes during catagen?

A

Apoptosis

123
Q

What form of Waardenburg syndrome (WS) does lethal white foal syndrome most closely resemble?

A

WS type IV

124
Q

What might you see on a trichogram from a cat with Chediak Higashi syndrome?

A

Macromelanosomes

125
Q

Is melanin production necessary for normal hearing?

A

No

126
Q

What is the mutation causing oculocutaneous albinism type I?

A

Tyrosinase

127
Q

In which dog breed have they demonstrated the presence of anti-melanocyte antibodies in vitiligo cases?

A

Belgian Tervurens

128
Q

What tissues are targeted by uveodermatologic syndrome?

A

Any melanin-containing tissue (eyes, skin, meninges, cochlea)

129
Q

What is the explanation for dark hair regrowth in a Siamese cat who has been shaved?

A

acromelanism – tyrosinase is only active at low temperatures. Shaving will lower the temperature in the area and tyrosinase will be active, resulting in melanin synthesis

130
Q

What color iris would you expect in a dog with albinism?

A

Blue

131
Q

A young collie is presented with a light-colored nose. Labs reveal thrombocytopenia and neutropenia though labs 2 weeks prior revealed a neutrophilia. The dog is smaller and weaker than his littermates. What gene is likely mutated?

A

AP3B1 (gray collie syndrome)

132
Q

What dog breed is predisposed to primary acanthosis nigricans?

A

Dachshunds

133
Q

What clinical feature helps differentiate Snow Nose from Dudley Nose?

A

Snow Nose usually incomplete depigmentation
Dudley Nose is complete depigmentation

134
Q

Name 3 drugs that have been associated with acquired hypopigmentation

A

Vitamin E
Ketoconazole
Procainamide

135
Q

What dog breeds are predisposed to vitiligo?

A

Rottweilers
Dobermans
Collies

136
Q

What cat breed is predisposed to vitiligo?

A

Siamese

137
Q

What are the autoantibody targets in vitiligo?

A

Tyrosinase
TYRP1
TYRP2
Melan-

138
Q

What are the targets of uveodermatologic yndrome?

A

tyrosinase
gp100

139
Q

What allele is increased in Akitas with uveodermatologic syndrome?

A

DLA-DQA1

MK ACVD Exam (17 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions