Genoderm Flashcards
Epidermolytic ichthyosis - genes
KRT1
KRT10 - no hands
Ichthyosis vulgaris - gene
FLG/ profillagrin
Semi autosomal dominant
Steroid sulfurase deficiency - gene
X linked recessive
STS gene deletion of Xp22.31
Gene associated with pilomatricoma and carcinoma
CTNNB1
Langerhanscell histiocytosis gene
BRAFV600E
Diagnostic criteria for NF1
CANFOOL Cafe au lait macules - >6, >5 mm pre-pubertal or >15 mm post Axillary freckling Neurofibromas - X2 any, X 1 plexiform First degree relative Osseus lesions Optic gliomas Lischn nodules
Epidermal naevus epidemiology
1 in 1000 infants
Epidermal naevus clinical features
- 80% occur within first year of life
- Most commonly single linear
- Well circumscribed, hyperpigmented papillomatous papules or plaques
- Asymptomatic
- Rarely - hypopigmented
- Can thicken and become more verrucous - particularly over joints
Rarely - malignant change, if so will be post-puberty - Location: commonly trunk and neck, follows lines of Blaschko
- Naevus verrucosus: warty appearance
- Naevus unius lateris: extensive, unilateral plaques, often involving the trunk
- Ichthyosis hystrix: extensive bilateral involvement, also on the trunk
- Epidermal naevus syndrome: epidermal naevi with other anomalies - CNS, MSK
Epidermal naevus pathogenesis (genes and what is it)
- Thought to originate from pluripotent cells in the basal layer of the embryonic epidermis, harmatomous process involves epidermis and at least some of papillary dwermis
- Possible mutations:
- Mutations identified in some: KRT1, KRT10, ATP2A2
- Common: FGFR3 mosaicism for activating mutations
- Have also found PIK3CA mutation
- RAS mutations have been observed in patients with keratinocytic epidermal naevi (HRAS>NRAS>KRAS)
Epidermal naevus histology
- epidermal hyperplasia
- hyperkeratosis
- acanthosis
- papillomatosis
- variable parakeratosis
- focal acantholytic dyskeratosis
Ddx epidermal naevus
- Naevus sebaceous
- Organoid naevi
- Lichen striatus
- Linear and whorled naevoid hypermelanosis
- Porokeratotic eccrine ostial and dermal duct naevus
- Linear LP
- X-linked dominant chondrodysplasia punctata
Treatment epidermal naevus
- Full thickness excision: recurrence is common, and can be complicated by scarring
- Topical therapies with limited benefit: steroids, retinoic acid, tars, anthralin, 5-FU, podophyllin
- Systemic therapy: retinoids –> decreases thickness
- Laser ablation –> however to be effective must induce scarring
PWS/Sturge Weber mode of inheritance and gene
GNAQ –> Q class G protein alpha subunits
Mosaic, with somatic mutations in lesional skin
Activating mutation
PWS/Phakomatosis pigmentovascularis type 2 or overgrwoth of an extremity
GNA11 –> Q class G protein alpha sub units
Mosaic, with somatic mutations in lesional skin
Activating mutation
Ataxia telangiectasia genetics
ATM gene - ATM protein is similar to phosphoinositol 3 kinase - regulates cell cycle, DNA repair, p53
Autosomal recessive
Loss of function
Capillary malformation-AVM genetics
RASA1 and EPHB4
loss of function - p120-Ras-GAP protein and EPH receptor B4 in endothelial cells - interact and modulate MAPK signaling growth factor receptors
Autosomal dominant
Cutaneous and mucosal venous malformations and Blue rubber bleb naevus syndrome genetics
TEK
Gain of function of TIE-2 - an endothelial cell-specific tyrosine kinase receptor that binds angiopoietins
Auutosomal dominant
Blue rubber bleb is mosaic
Venous malformations genetics
TEK, PIK3CA
Gain of function of TIE-2 –> binds angiopoietins
PIK3CA - activates the AKT/mTOR pathway
Lymphatic malformations genetics
PIK3CA - gain of function
TIE2 –> binds angiopoietins
PIK3CA activates the AKT/mTOR pathway
Mosaic, with somatic mutations in lesional tissue
Hereditary lymphoedema genetics
GJC2
Loss of function: connexin 47 in gap junctions of lymphatic vessels
autosomal dominant
CADASIL genetics
NOTCH3
Accumulation of NOTCH-3 protein in vascular smooth muscle cells
Phakomatosis pigmentovascularis 1
Epidermal naevus + port wine stain
<5% of PPV cases
Phakomatosis pigmentovascularis 2
Mongolian spots + PWS
75% of PPV cases
Other associations: naevus anaemicus, hypotrichosis, lipohypoplasia, hypoplastic nails
Phakomatosis pigmentovascularis 3
Naevus spilus + naevus roseus
Other: naevus anaemicus, lymphoedema, hypotrichosis
Phakomatosis pigmentovascularis 4
CALM + capillary malformation
Other: naevus anaemicus, naevoid hyper or hypopigmentation, naevus sebaceous
Phakomatosis pigmentovascularis 5
Dermal melanocytosis + cutis marmorata telangiectatica congenita
Sjogren larsson epi
- Autosomal recessive
- Prevalence <1 in 100 000
- Most common in northern Sweden
Sjogren larsson genetics and path
- Deficiency of microsomal fatty aldehyde dehydrogenase enzyme
- Mutations in ALDH3A2
- results in membrane alterations due to accumulation of fatty alcohol or fatty aldehyde modified lipids and proteins
- retarded myelination and variable degree of dysmyelination in periventricular white matter
Sjogren larsson clinical
- Cutaneous:
- Birth: erythema, hyperkeratosis, scaling. Rarely colloidon.
- Hyperkeratosis then becomes darker
- Ichthyosis varies from fine, white scales to larger, plate-like scales
- Prediliction: lower abdomen, neck and flexural areas
- Palmoplantar keratoderma - 70% patients
- Lichenification of flexural areas
- Extra-cutaneous:
- Ophthal: perifoveal glistening white dots in the ocular fundus - juvenile macular dystrophy
- CNS: delayed motor development, abnormal gait, pyramidal signs, spasticity, contractures. Seizures in 40%. MRI: white matter disease
Sjogren larrson diagnosis
- Histopath: orthokeratotic hyperkeratosis, papillomatosis and moderate acanthosis, well-developed granular layer
- Cultured skin fibroblasts/keratinocytes/leukocytes have reduced or absent FALDH activity
- SLS in detection of elevated free fatty alcohol in cultured fibroblasts and plasma also helpful
- Preferred method of diagnosis is DNA based molecular testing
- Can do pre-natal molecular diagnosis from CVS or amniocentesis
Refsum epidemiology and path
- Super rare
- Autosomal recessive - PAHX gene on 10p, and PEX7 on 6q
- M=F
- Deficiency in phytanoyl-CoA hydroxylase –> accumulation of phytanic acid in the serum
Refsum clinical
- Cutaneous: mild ichthyosis, begins after neurological symptoms
- CNS: ataxia, progressive peripheral polyneuropathy
- Eyes: retinitis pigmentosa with salt and pepper pigment
- ENT: deafness
- Arrhythmias, cardiac failure
Refsum diagnosis
- Cultured fibroblasts: increased serum phytanic acid
- DNA mutational analysis if mutation known
Refsum management
- Dietary restriction of phytanic acid - decrease green vegetables, dairy products and ruminant fats
- Plasma exchange removal of phytanic acid
- If diet and exchange instituted early on, progression of disease can be halted
Nail patella syndrome genetic mutation
LMX1B, AD
Aplastic or hypoplastic nails and patella, and renal issues - 40% nephropathy, 8% renal insufficiency
Iliac horns on pelvic x-ray
triangle shaped lunula
Goltz mutation and epi
PORCN ++ females
Goltz clinical
- Cutaneous: worm like atrophoderma, fat herniation, raspberry papillomas
- Other ectodermal: nail dystrophy, sparse hair, dentition (hypodontia)
- Eyes: unilateral, microphthalmia etc
- Bone: 80% limb abnormalities
- Dysmorphic facies - pointed chin, large malformed ears, etc
Dyskeratosis congenita main features and pathogenesis
Telomere shortening
DYC 1 + other mutations
- Reticulate hyperpigmentation - generalized
- Oral leukoplakia
- Nail dystrophy - pterygium
- BM failure
- Incr risk malignancy: SCC, AML, GI malignancy
- Other: liver cirrhosis, lung fibrosis, cryptorchidism, hypogonadism, incr risk infections, short stature, developmental delay
Dowling Degos clinical and pathogenesis
KRT5 mutation, M>F, AD Clin: onset 30s-40s - flexural reticulate hyperpigmentation open comedones cysts acne HS assoc: HS, SCCs, KAs, nail dystrophy, seb ks, cysts
Chediak Higashi main clinical features
NUPBOIL Neuro - DD, etc Ulcerations - PG, oral ulceratio, etc Pigment - bronze colour Bleeding - bruises, ecchymoses Ocular - nyastagmus, strabismus, no change in visual acuity Infections - skin, resp Lymphoproliferative - HLH sx, and also LYST gene mutation
Chronic granulomatous disease main features
M>F 90%
Reduced NADPH
Clinical:
1. Cutaneous: staph infections, sterile cutaneous, lupus like piccture
2. Extra-cutaneous: lymphadenitis, granulomas elsewhere - GIT - looks like IBD, can basically be anywhere
Omenn syndrome/SCID main features
Defective cell and humoral immunity
X linked
Omenn: RAG1 and RAG2 mutation
SCID - ADA important one (associated with DFSP)
Clinical:
1. Cutaneous: maternofoetal GVHD - seb derm, morbilliform, then eczema, erythroderma, alopecia. ADA linked with DFSP - multiple in 10s-20s
2. Chronic diarrhoea, failure to thrive, HSM, LN, recurrent infections
Need to diagnose early before give blood products etc
Rx: IVIG, HSCT, ADA replacement
Wiskott Aldrich Syndrome main features
WASP mutation X linked - boys Clinical - TIME Thrombocytopaenia - bleeding Infections - cutaneous, resp tract, CNS, etc Malignancy - lymphoma Eczema
Hermansky Pudlak main features
BLOC 1/2/3 mutation
Pigmentary dilution Ulcers – knife cut ulcers and granulomas intertriginous Decreased vision Lungs - pul fibrosis AR K vitamin K not working à bleeder
Rothmund thompson gene and features
RECQL4 mutation THOMPSON: - Teeth abnormalities - Ocular: cataracts - Microcephaly - Photosensitivity, poikiloderma, perforating - Short - Osteosarcoma + other cancers - No hair
Ddx for photosensitive genodermatoses
XP Rothmund Thompson Bloom Sx Cockayne Sx Trichothiodystrophy
Cockayne sx gene and features
- Autosomal recessive
- defective transcription coupled NER –> inability to recover mRNA synthesis after exposure to UVR
- 2/3 have mutation in ERCC6, 1/3 in ERCC8
- Don’t get skin cancers –> cells with low level damage are eliminated
Clinical
- Cutaneous:
- Photosensitivity, pigmented macules
- Loss of subcutaneous fat
- No increased risk of malignancy
- Alopecia
- Premature ageing
- Hypohidrosis
- Acral oedema
- Stellate scars
- Cold extremities
- CNS:
- Basal ganglia calcification
- Sensorineural hearing loss
- Intention tremor
- Ocular
- Pigmentary retinal degeneration - ‘salt and pepper’
- Cataracts
- Nyastagmus and strabismus
- Dysmorphic facies
- Sunken eyes due to loss of adipose tissue
- Progeria
- Beaked nose
- Ortho
- Stooped posture
- Cachetic dwarfism
- Joint contractures
Bloom syndrome gene and features
BLM mutation BLOOM: - Butterfly rash - Leukaemias, lymphomas and carcinomas - Oral: lower lip blistering - Otic and pulmonary infections - Macules: cafe aut lait macules
Goltz syndrome gene and features
X linked, females only, PORCN
- Linear dermal atrophy, fat herniations, raspberry like papillomas
- 80% limb problems - skeletal
- Ocular
- Nail
- Hair
- Dysmorphic face
EN syndrome
FGFR/PIK3CA/AKT1 mutation or RAS/MAPK mutation
Cutaneous: EN, seb naevus, dyspigmentation, CALM, aplasia cutis congenita
CNS: hemimegalencephaly, seizures, DD
Ocular: coloboma, lipodermoids, etc
Skeletal: Ricketts, asymmetry, kyphoscoliosis etc
Other: cardiac, malignancy
Genes for EB
EB simplex - KRT 5 and 14
Junctional EB - laminin 332
Dystrophic EB - collagen 7
Hypohidrotic ectodermal dysplasia gene and features
Ectodysplasin - X linked most commonly 1. Sparse hair 2. Hypodontia - conical teeth 3. Reduced ability to sweat 4. Cutaneous: atopy, loss of dermatoglyphs, colloidon baby like 5. Dysmorphic facies NORMAL NAILS
Hypohidrotic ectodermal dysplasia with immune deficiency gene and features
NEMO, AD Milder than without immune def 1. Hypotrichosis 2. Hypodontia 3. Inability to sweat 4. Cutaneous: seb derm, erythrodermic 5. Pyogenic infection
Hidrotic ED - Clouston - gene and features
GJB6 mutation AD
Hair: wiry, brittle, pale
Nails: milky white
PPK - pebbled skin
Monilethrix gene
AD, Hb1 and 6 (KRT 81 and 86)