Keratoderma, Palmoplantar: Group of mostly hereditary disorders characterized by thickening of the palms and soles as a result of excessive keratin formation leading to hypertrophy of the stratum corneum (hyperkeratosis).Keratoderma, Palmoplantar, Epidermolytic: An autosomal dominant hereditary skin disease characterized by epidermolytic hyperkeratosis that is strictly confined to the palms and soles. It has been associated with mutations in the gene that codes for KERATIN-9.Keratoderma, Palmoplantar, Diffuse: An autosomal dominant disorder characterized by a widely distributed, well-demarcated hyperkeratosis of the palms and soles. There is more than one genotypically distinct form, each of which is clinically similar but histologically distinguishable. Diffuse palmoplantar keratoderma is distinct from palmoplantar keratoderma (KERATODERMA, PALMOPLANTAR), as the former exhibits autosomal dominant inheritance and hyperhidrosis is frequently present.Keratoconus: A noninflammatory, usually bilateral protrusion of the cornea, the apex being displaced downward and nasally. It occurs most commonly in females at about puberty. The cause is unknown but hereditary factors may play a role. The -conus refers to the cone shape of the corneal protrusion. (From Dorland, 27th ed)Nails, Malformed: Deformities in nail structure or appearance, including hypertrophy, splitting, clubbing, furrowing, etc. Genetic diseases such as PACHYONYCHIA CONGENITA can result in malformed nails.Keratin-1: A type II keratin that is found associated with the KERATIN-10 in terminally differentiated epidermal cells such as those that form the stratum corneum. Mutations in the genes that encode keratin-1 have been associated with HYPERKERATOSIS, EPIDERMOLYTIC.Foot Dermatoses: Skin diseases of the foot, general or unspecified.Hair Diseases: Diseases affecting the orderly growth and persistence of hair.Pachyonychia Congenita: A group of inherited ectodermal dysplasias whose most prominent clinical feature is hypertrophic nail dystrophy resulting in PACHYONYCHIA. Several specific subtypes of pachyonychia congenita have been associated with mutations in genes that encode KERATINS.Ichthyosis: Any of several generalized skin disorders characterized by dryness, roughness, and scaliness, due to hypertrophy of the stratum corneum epidermis. Most are genetic, but some are acquired, developing in association with other systemic disease or genetic syndrome.Hyperkeratosis, Epidermolytic: A form of congenital ichthyosis inherited as an autosomal dominant trait and characterized by ERYTHRODERMA and severe hyperkeratosis. It is manifested at birth by blisters followed by the appearance of thickened, horny, verruciform scales over the entire body, but accentuated in flexural areas. Mutations in the genes that encode KERATIN-1 and KERATIN-10 have been associated with this disorder.Keratin-16: A type I keratin expressed in a variety of EPITHELIUM, including the ESOPHAGUS, the TONGUE, the HAIR FOLLICLE and NAILS. Keratin-16 is normally found associated with KERATIN-6. Mutations in the gene for keratin-6 have been associated with PACHYONYCHIA CONGENITA, TYPE 1.Papillon-Lefevre Disease: Rare, autosomal recessive disorder occurring between the first and fifth years of life. It is characterized by palmoplantar keratoderma with periodontitis followed by the premature shedding of both deciduous and permanent teeth. Mutations in the gene for CATHEPSIN C have been associated with this disease.Paralysis, Hyperkalemic Periodic: An autosomal dominant familial disorder which presents in infancy or childhood and is characterized by episodes of weakness associated with hyperkalemia. During attacks, muscles of the lower extremities are initially affected, followed by the lower trunk and arms. Episodes last from 15-60 minutes and typically occur after a period of rest following exercise. A defect in skeletal muscle sodium channels has been identified as the cause of this condition. Normokalemic periodic paralysis is a closely related disorder marked by a lack of alterations in potassium levels during attacks of weakness. (Adams et al., Principles of Neurology, 6th ed, p1481)Desmoplakins: Desmoplakins are cytoskeletal linker proteins that anchor INTERMEDIATE FILAMENTS to the PLASMA MEMBRANE at DESMOSOMES.Hand DermatosesKeratolytic Agents: Agents that soften, separate, and cause desquamation of the cornified epithelium or horny layer of skin. They are used to expose mycelia of infecting fungi or to treat corns, warts, and certain other skin diseases.Desmoglein 1: A desmosomal cadherin that is an autoantigen in the acquired skin disorder PEMPHIGUS FOLIACEUS.Keratin-6: A type II keratin found associated with KERATIN-16 or KERATIN-17 in rapidly proliferating squamous epithelial tissue. Mutations in gene for keratin-6A and keratin-6B have been associated with PACHYONYCHIA CONGENITA, TYPE 1 and PACHYONYCHIA CONGENITA, TYPE 2 respectively.Keratin-7: A type II keratin found associated with KERATIN-19 in ductal epithelia and gastrointestinal epithelia.Cathepsin C: A papain-like cysteine protease that has specificity for amino terminal dipeptides. The enzyme plays a role in the activation of several pro-inflammatory serine proteases by removal of their aminoterminal inhibitory dipeptides. Genetic mutations that cause loss of cathepsin C activity in humans are associated with PAPILLON-LEFEVRE DISEASE.Keratosis: Any horny growth such as a wart or callus.Ointment Bases: Various mixtures of fats, waxes, animal and plant oils and solid and liquid hydrocarbons; vehicles for medicinal substances intended for external application; there are four classes: hydrocarbon base, absorption base, water-removable base and water-soluble base; several are also emollients.Pediococcus: A genus of gram-positive, facultatively anaerobic bacteria whose growth is dependent on the presence of a fermentable carbohydrate. No endospores are produced. Its organisms are found in fermenting plant products and are nonpathogenic to plants and animals, including humans.Ectodermal Dysplasia: A group of hereditary disorders involving tissues and structures derived from the embryonic ectoderm. They are characterized by the presence of abnormalities at birth and involvement of both the epidermis and skin appendages. They are generally nonprogressive and diffuse. Various forms exist, including anhidrotic and hidrotic dysplasias, FOCAL DERMAL HYPOPLASIA, and aplasia cutis congenita.Petrolatum: A colloidal system of semisolid hydrocarbons obtained from PETROLEUM. It is used as an ointment base, topical protectant, and lubricant.Sternocostal Joints: An articulation where the costal cartilage of each rib fit with slight concavities along the lateral borders of the STERNUM.Deafness: A general term for the complete loss of the ability to hear from both ears.Keratins: A class of fibrous proteins or scleroproteins that represents the principal constituent of EPIDERMIS; HAIR; NAILS; horny tissues, and the organic matrix of tooth ENAMEL. Two major conformational groups have been characterized, alpha-keratin, whose peptide backbone forms a coiled-coil alpha helical structure consisting of TYPE I KERATIN and a TYPE II KERATIN, and beta-keratin, whose backbone forms a zigzag or pleated sheet structure. alpha-Keratins have been classified into at least 20 subtypes. In addition multiple isoforms of subtypes have been found which may be due to GENE DUPLICATION.Acquired Hyperostosis Syndrome: Syndrome consisting of SYNOVITIS; ACNE CONGLOBATA; PALMOPLANTAR PUSTULOSIS; HYPEROSTOSIS; and OSTEITIS. The most common site of the disease is the upper anterior chest wall, characterized by predominantly osteosclerotic lesions, hyperostosis, and arthritis of the adjacent joints. The association of sterile inflammatory bone lesions and neutrophilic skin eruptions is indicative of this syndrome.Psoriasis: A common genetically determined, chronic, inflammatory skin disease characterized by rounded erythematous, dry, scaling patches. The lesions have a predilection for nails, scalp, genitalia, extensor surfaces, and the lumbosacral region. Accelerated epidermopoiesis is considered to be the fundamental pathologic feature in psoriasis.Skin Diseases, Vascular: Skin diseases affecting or involving the cutaneous blood vessels and generally manifested as inflammation, swelling, erythema, or necrosis in the affected area.Porosity: Condition of having pores or open spaces. This often refers to bones, bone implants, or bone cements, but can refer to the porous state of any solid substance.Epidermis: The external, nonvascular layer of the skin. It is made up, from within outward, of five layers of EPITHELIUM: (1) basal layer (stratum basale epidermidis); (2) spinous layer (stratum spinosum epidermidis); (3) granular layer (stratum granulosum epidermidis); (4) clear layer (stratum lucidum epidermidis); and (5) horny layer (stratum corneum epidermidis).Syndrome: A characteristic symptom complex.Frameshift Mutation: A type of mutation in which a number of NUCLEOTIDES deleted from or inserted into a protein coding sequence is not divisible by three, thereby causing an alteration in the READING FRAMES of the entire coding sequence downstream of the mutation. These mutations may be induced by certain types of MUTAGENS or may occur spontaneously.Desmosomes: A type of junction that attaches one cell to its neighbor. One of a number of differentiated regions which occur, for example, where the cytoplasmic membranes of adjacent epithelial cells are closely apposed. It consists of a circular region of each membrane together with associated intracellular microfilaments and an intercellular material which may include, for example, mucopolysaccharides. (From Glick, Glossary of Biochemistry and Molecular Biology, 1990; Singleton & Sainsbury, Dictionary of Microbiology and Molecular Biology, 2d ed)Skin DiseasesConnexins: A group of homologous proteins which form the intermembrane channels of GAP JUNCTIONS. The connexins are the products of an identified gene family which has both highly conserved and highly divergent regions. The variety contributes to the wide range of functional properties of gap junctions.Arrhythmogenic Right Ventricular Dysplasia: A congenital cardiomyopathy that is characterized by infiltration of adipose and fibrous tissue into the RIGHT VENTRICLE wall and loss of myocardial cells. Primary injuries usually are at the free wall of right ventricular and right atria resulting in ventricular and supraventricular arrhythmias.Osteitis: Inflammation of the bone.Acitretin: An oral retinoid effective in the treatment of psoriasis. It is the major metabolite of ETRETINATE with the advantage of a much shorter half-life when compared with etretinate.Hyperhidrosis: Excessive sweating. In the localized type, the most frequent sites are the palms, soles, axillae, inguinal folds, and the perineal area. Its chief cause is thought to be emotional. Generalized hyperhidrosis may be induced by a hot, humid environment, by fever, or by vigorous exercise.Sternoclavicular Joint: A double gliding joint formed by the CLAVICLE, superior and lateral parts of the manubrium sterni at the clavicular notch, and the cartilage of the first rib.Hyperplasia: An increase in the number of cells in a tissue or organ without tumor formation. It differs from HYPERTROPHY, which is an increase in bulk without an increase in the number of cells.Mutation: Any detectable and heritable change in the genetic material that causes a change in the GENOTYPE and which is transmitted to daughter cells and to succeeding generations.DNA Mutational Analysis: Biochemical identification of mutational changes in a nucleotide sequence.Genes, Dominant: Genes that influence the PHENOTYPE both in the homozygous and the heterozygous state.Dermatologic Agents: Drugs used to treat or prevent skin disorders or for the routine care of skin.Skin: The outer covering of the body that protects it from the environment. It is composed of the DERMIS and the EPIDERMIS.Family Health: The health status of the family as a unit including the impact of the health of one member of the family on the family as a unit and on individual family members; also, the impact of family organization or disorganization on the health status of its members.Pyoderma: Any purulent skin disease (Dorland, 27th ed).Nail Diseases: Diseases of the nail plate and tissues surrounding it. The concept is limited to primates.Foot: The distal extremity of the leg in vertebrates, consisting of the tarsus (ANKLE); METATARSUS; phalanges; and the soft tissues surrounding these bones.Pityriasis Rosea: A mild exanthematous inflammation of unknown etiology. It is characterized by the presence of salmon-colored maculopapular lesions. The most striking feature is the arrangement of the lesions such that the long axis is parallel to the lines of cleavage. The eruptions are usually generalized, affecting chiefly the trunk, and the course is often self-limiting.