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Dermatology Board Prep > DERM (09) Genodermatoses > Disorders of the Hair/Nail/Ectodermal dysplasias > Flashcards

Disorders of the Hair/Nail/Ectodermal dysplasias Flashcards

1
Q

What is the gene and mode of inheritance in pachyonychia congenita?

A

KRT6A, KRT6B, KRT16, KRT17

AD

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2
Q

What are the 3 primary characteristics of in pachyonychia congenita?

A

Onychodystrophy, plater keratoderma, and plantar pain

  • These develop in childhood
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3
Q

What is the appearance of the onychodystrophy in pachyonychia congenita?

A

Discoloration and progressive hyperkeratosis of the nail plate and is most pronounced at the free edge giving it a pincer-like appearance

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4
Q

What are the acral skin findings in pachyonychia congenita?

A

Most severe on the palmar surfaces

Focal, painful, keratoderma and hyperhidrosis –> leads to secondary bullae and fissures (develop in childhood)

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5
Q

What are the two types of pachyonychia congenita?

A

Type I: Jadassohn-Lewandowski

Type II: Jackson-Lawler

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6
Q

What genes are involved in pachyonychia congenita type I?

A

These are the KRT6A and KRT16

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7
Q

What is the phenotype of pachyonychia congenita type I?

A

Full expression happens later, usually not until late childhood or adulthood

Recurrent paronychia

Get benign oral leukoplakia of the tongue and buccal mucosa

Follicular hyperkeratosis of knees, elbows, back, and buttocks

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8
Q

What is the phenotype of pachyonychia congenita type II?

A

Natal teeth
Steatocytomas
More mild keratoderma

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9
Q

What are the genes involved in pachyonychia congenita type II?

A

KRT6B and KRT17

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10
Q

What is the broad definition of the ectodermal dysplasias?

A

It is a heterogeneous group of genetic disorders that affect the hair/teeth/nails/eccrine glands to different degrees

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11
Q

What is the gene and inheritance of hypohidrotic ectodermal dysplasia?

A

Ectodysplasin (ED1) in classical cases (XLR)

Less commonly can have AD/AR mutations in ectodysplasin receptor (EDAR and ectodysplasin receptor-associated death domain (EDARDD)

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12
Q

Can female carriers of hypohidrotic ectodermal dysplasia have symptoms?

A

Yes, they get features that are segmental from random inactivation (alopecia, dental defects, and Blaschkoid linear patches of hypohidrosis

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13
Q

What is the clinical triad of hypohidrotic ectodermal dysplasia?

A

Decreased sweating, hypotrichosis, and abnormal dentition

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14
Q

What facial features can be seen in hypohidrotic ectodermal dysplasia?

A

Frontal bossing, large nostrils, wide/flat malar cheeks, thick everted lower lip, and prominent chin

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15
Q

What are the skin findings in hypohidrotic ectodermal dysplasia?

A

Thin, wrinkled, soft skin; darkening of the skin under the eyes

Mild onychodystrophy

Hair: can have hypotrichosis w/ thin, light hair; eyelashes absent

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16
Q

What are the teeth findings in hypohidrotic ectodermal dysplasia?

A

Delayed dentition, may have peg-shaped, conical or missing teeth

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17
Q

What are the systemic findings seen in hypohidrotic ectodermal dysplasia?

A

Risk of hyperthermia w/ the hypohidrosis, decreased lacrimation can be seen, can get sinus dz, pulmonary infections and asthma

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18
Q

What is the phenotype and cause of hypohidtrotic ectodermal dysplasia w/ immunodeficiency?

A

IKBKG/NEMO (XLR) or NFKBIA (AD)

These pts are susceptible to recurrent pyogenic and atypical mycobacterial infections

Board factoid

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19
Q

What is the involved gene and mode of inheritance of hidrotic ectodermal dysplasia?

A

Connexin 30 (GJB6)

AD

20
Q

What is the clinical triad of hidrotic ectodermal dysplasia?

A

Marked onychodystrophy/chronic paronychia, palmoplantar keratoderma, and hair abnormalities

21
Q

Important differences between the hypohidrotic and hidrotic ectodermal dysplasias?

A

In the hidrotic ectodermal dysplasia:

  • Marked onychodystrophy, also marked hypotrichosis w/ thin brittle hair
  • Normal sweating, facial features, and teeth
  • Ophthalmologic and MSK sequelae: tufted distal phalanges, conjunctivitis, strabismus and cataracts
22
Q

What is the gene involved in ectodermal dysplasia due to p63 mutation and what is the inheritance pattern?

A

P63, AD

23
Q

What is p63 important for?

A

Critical transcription factor for ectodermal, orofacial, and limb development

24
Q

How many defined clinical ectodermal dysplasia syndromes arising from p63 are there and what are they?

A

There are 4

  1. Rapp-Hodgkin syndrome
  2. Ankyloblepharon-ectodermal dysplasia-clefting syndrome (AEC)
  3. Ectodactyly ectodermal dysplasia-cleft lip/palate syndrome
  4. acro-dermato-ungual lacrimal-toot/limb-mammary syndrome, split hand-foot malformation

All of these have wiry/sparse hair, dystrophic nails, decreased number of teeth/hypoplastic enamel, hypohidrosis, decreased number of teeth/hypoplastic enamal, hypohidrosis, short stature, and poor weight gain

25
Q

What is the Rapp-Hodgkin syndrome?

A

P63 ectodermal dysplasia, leads to clefting of lip/palate/uvula, hypoplasia of maxilla, small narrow nails, and small conical teeth

26
Q

What is ankyloblepharon-ectodermal dysplasia-clefting syndrome?

A

Congenital fusion of eyelids (ankyloblepharon) and is a/w/ facial clefting or mid-face hypoplasia; diffuse collodion-like peeling/erythema seen at birth

  • The scalp can have chronic erosive dermatitis –> can get frequent staph infections
27
Q

What is the ectrodactyly ectodermal dysplasia-cleft lip/palate syndrome?

A

Ectrodactyly (developmental anomaly of a median ray of feet > hands which leads to “lobster claw” anomaly (missing digits/deformity of extremities), facial clefting, mild PPK, conductive hearing loss, and genitourinary anomalies

28
Q

What is the gene and mode of inheritance in Rubinstein-Taybi syndrome?

A

CREBBP

Sporadic

29
Q

What is the clinical phenotype in Rubinstein-Taybi syndrome?

A

Broad thumbs/halluces w/ racquet nails (brachyonychia)

  • Capillary malformations, short, severe mental retardation, cryptorchidism, congenital heart defects, and typical facies (beaked nose, down slanting palpebral fissures, low-set ears, epicanthal folds, and grimacing smile), multiple pilomatrixoma
30
Q

What is atrichia w/ papules?

A

Mutations in the hairless gene (HR)

  • Hair normal at birth –> shed then doesn’t come back and you get milia-like papules that appear later
  • can be a/w Vitamin-D resistant rickets
  • Basically causes disintegration of the lower 2/3 of hair follicle
31
Q

What are the two wooly hair genoderms?

A

Naxos: right ventricular cardiomyopathy, wooly hair

Carvajal: right ventricular cardiomyopathy, wooly hair

32
Q

What is the underlying defect/issue with uncombable hair?

A

Pili trianguli et canalculi (so on EM cross section the hair looks triangular and there is a longitudinal depression

  • Looks like shiny, “spun-glass” look
33
Q

What is monilethrix?

A

There are uniform elliptical nodules along the hair shaft

  • Hair normal at birth then in infancy it becomes brittle, short and has a beaded appearance
  • A/w keratosis pilaris
  • KRT81, KRT83, and KRT86 (AD) and desmoglein 4 (AR)
34
Q

What is the appearance of pili torti?

A

Flattened, twisted hair shafts occuring at irregular intervals

35
Q

What syndromes are a/w pili torti?

A

Menkes kinky hair syndrome, Bazex-Dupre-Christol syndrome, Rombo syndrome, Bjornstad syndrome, crandal syndrome

36
Q

What is the appearance of trichorrhexis nodosa?

A

Light microscopy: nodules w/ the appearance of broom bristles

37
Q

What are the most commonly associated genetic conditions w/ trichorrhexis nodosa?

A

Arginosuccinic aciduria, citrullinemia, oculo-dental-digital dysplasia, trichothiodystrophy, Netherton syndrome

38
Q

What is the appearance of the trichorrhexis invaginata?

A

This has a ball in socket appearance, the end can look like a “golf tee”

39
Q

What disease is trichorexis invaginata a marker for?

A

Netherton syndrome

40
Q

What is Marie Unna hypotrichosis?

A

AD mutations in U2HR

Absence of scalp hair, eyebrows, and eyelashes at birth

Hair growth when it comes is coarse and twisted

41
Q

What is the pathogenesis of loose anagen syndrome?

A

Can AD but usually sporadic mutation leading to defective inner root sheath keratinization so that the anagen hairs can be easily and painlessly plucked

42
Q

What is the clinical phenotype in loose anagen syndrome?

A

Diffuse hair thinning, Hair can look fine, limp, and matted

On trichoscopy there are multiple anagen hairs (hockey sticks) that have a ruffled cuticles

43
Q

What is Cornelia de Lange syndrome?

A

AD (mutation in NIPBL)

Hirsutism, synophrys, trichomegaly, low hairline, mental/psychomotor retardation, short stature, simian crease, cryptorchidism, hypospadias, renal issues, heart defects, lung infections

  • Can lead to death or hearing loss
44
Q

What is Ambras syndrome?

A

Excessive vellus-like hairs on the face, ears, and shoulders

45
Q

What is keratosis Polaris atrophicans, ulerthema ophyrogenes subtype?

A

Erythematous papules w/ follicular plugging and atrophic scarring

  • You get scarring alopecia of the eyebrows (especially lateral part)

DERM (09) Genodermatoses (13 decks)

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