Table 1.
Inherited cutaneous keratin disorders due to keratin mutations
| Human cutaneous keratin disorder | Mode of inheritance | Type II keratin | Type I keratin | Tissue specific expressions | Clinical characteristics |
|---|---|---|---|---|---|
| Epidermolysis bullosa simplex | AD | K5 | K14 | Basal keratinocytes of the epidermis | Localized, generalized and /or herpetiformblistering, PPK |
| Localized EBS (EBS-Loc) | ......“..... | Localized blistering in friction areas as in palms and soles, | |||
| Generalized non-Dowling meara EBS (gen-nonDM-EBS) | ......“..... | ....“...... | Generalized, “non herpetiform” mild blistering | ||
| EBS Dowling Meara (EBS-DM) | ......“..... | Generalized “herpetiform” blistering, may involve nail oral and other mucosa | |||
| Epidermolysis bullosa simplex (EBS-AR) | AR | K14 | .....“..... | Generalized blistering, ichthyotic plaques and may involve extra-cutaneous area, absent /reduced KIF in basal keratinocytes | |
| EBS with migratory circinate erythema (EBS-CE) | K5 | ......“..... | Generalized blistering, circinate erythroderma, brown hyperpigmentation, reduced KIF in basal keratinocytes | ||
| EBS with mottled pigmentation (EBS-MP) | K5 | K14 | ......“..... | Generalized blistering, reticulate/mottled brown hyperpigmentation, KIF aggregation and increased melanosomes in basal keratinocytes | |
| Dowling-Degos disease (DDD) | K5 | ......“..... | Hyperkeratotic papules, reticulate, progressive and disfiguring hyperpigmentation, primarily in the flexural areas | ||
| Naegeli-Franceschetti-Jadassohn syndrome (NFJS)/ Dermatopathia pigmentosa reticularis (DPR) | AD null | K14 | ......“..... | both share reticulate hyperpigmentation of skin, thickening of the palms and soles (PPK), signs of ectodermal dysplasia, such as abnormal sweating and absence of dermatoglyphics | |
| Epidermolytic ichthyosis (EI) | AD | K1 | K10 | Suprabasal keratinocytes of the epidermis | Erythroderma, blister formation, development of hyperkeratosis, PPK |
| Linear epidermal nevus (LEN) | AD | K1 | K10 | Epidermal hamartomas showing somatic mosaicism of epidermolytic hyperkeratosis | |
| Epidermolytic ichthyosis (EI) | AR | K10 | Erythroderma, blister formation, hyperkeratosis | ||
| Ichthyosis hystrix Curth-Macklin (IHCM) | K1 | Severe and spiky palmoplantar hyperkeratosis | |||
| Diffuse non-epidermolytic PPK (DNEPPK) | K1 | Upper suprabasal keratinocytes of palmoplantar skin | Demarcated diffuse PPK, | ||
| Palmoplantar keratoderma with tonotubules (PPK) | K1 | Upper suprabasal keratinocytes of palmoplantar skin | Diffuse PPK, erythematous margin | ||
| Ichthyosis bullosa of Siemens (IBS) | K2 | Upper suprabasal keratinocytes of cornifying epithelia | Superficial blistering and shedding or desquamation of the epidermis, with age dark brown hyperkeratosis | ||
| Epidermolytic palmoplantar keratoderma (EPPK) | K9 | Suprabasal layers of palmoplantar epidermis (palms and soles) | Diffuse PPK, erythematous margin, +- EHK/ suprabasal KIF clumping | ||
| Pachyonychia congenita type I (PCI) | K6a | K16 | Suprabasal orogenital mucosa; palmoplantar epidermis; epidermal appendages (nail) | Nail dystrophy, mild PPK, multiple pilosebaceous cysts, oral leukokeratosis | |
| Pachyonychia congenita type II (PCII) | K6b | K17 | Nail dystrophy and may involve hair follicle, and eccrine glands, mild PPK, pilosebaceous cysts, | ||
| Steatocystoma multiplex (SM) | K17 | Several and widespread distribution of cystic tumors | |||
| Focal non-epidermolytic PPK (FNEPPK) | K16 | Focal PPK with oral, genital, and/or follicular lesions | |||
| Monilethrix | AR, co-dominance | K81, 86, 83 | Hair shaft, (clumps of the structural protein s) | Hair dystrophy, varying degrees of alopecia | |
| Pseudofolliculitis barbae (PFB) | K75i | Hair follicle root sheath | Follicular infections, ingrowth hair follicles, affects mainly black individuals | ||
| Ectodermal dysplasia of hair and nail type | K85 | Hair shaft | Congenital onychodystrophy, brittle hair, and hypotrichosis |
AD autosomal dominant, AR autosomal recessive, KIF keratin intermediate, PPK palmoplantar keratoderma
i
mutations are risk factors but not a causative association