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Anonychia
Anonychia is the absence of fingernails or toenails, an anomaly which may be the result of a congenital ectodermal defect, ichthyosis, severe infection, severe allergic contact dermatitis, self-inflicted trauma, Raynaud phenomenon, lichen planus, epidermolysis bullosa, or severe exfoliative diseases.James, William; Berger, Timothy; Elston, Dirk (2005). ''Andrews' Diseases of the Skin: Clinical Dermatology''. (10th ed.). Saunders. . Congenital form This is rare and is usually due to mutations in the R-spondin 4 ( RSPO4) gene which is located on the short arm of chromosome 20 Chromosome 20 is one of the 23 pairs of chromosomes in humans. Chromosome 20 spans around 66 million base pairs (the building material of DNA) and represents between 2 and 2.5 percent of the total DNA in cells. Chromosome 20 was fully sequenced i ... (20p13).Khan TN, Klar J, Nawaz S, Jameel M, Tariq M, Malik NA, Baig SM, Dahl N (2012) Novel missense mutation in the RSPO4 gene in congenital hyponychia and ev ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
RSPO4
For chromosome 20, R-spondin 4 is a protein in humans that is encoded by the RSPO4 gene. This gene encodes a member of the R-spondin family of proteins that share a common domain organization consisting of a signal peptide, cysteine-rich/furin-like domain, thrombospondin domain and a C-terminal basic region. The encoded protein may be involved in activation of Wnt/beta-catenin signaling pathways. Mutations in this gene are associated with anonychia Anonychia is the absence of fingernails or toenails, an anomaly which may be the result of a congenital ectodermal defect, ichthyosis, severe infection, severe allergic contact dermatitis, self-inflicted trauma, Raynaud phenomenon, lichen planus .... Alternate splicing results in multiple transcript variants. rovided by RefSeq, Sep 2009 References Further reading * * * * * * * * Genes on human chromosome 20 Glycoproteins Extracellular matrix proteins {{gene-20-stub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
List Of Cutaneous Conditions
Many skin conditions affect the human integumentary system—the organ system covering the entire surface of the body and composed of skin, hair, nails, and related muscle and glands. The major function of this system is as a barrier against the external environment. The skin weighs an average of four kilograms, covers an area of two square metres, and is made of three distinct layers: the epidermis, dermis, and subcutaneous tissue. The two main types of human skin are: glabrous skin, the hairless skin on the palms and soles (also referred to as the "palmoplantar" surfaces), and hair-bearing skin.Burns, Tony; ''et al''. (2006) ''Rook's Textbook of Dermatology CD-ROM''. Wiley-Blackwell. . Within the latter type, the hairs occur in structures called pilosebaceous units, each with hair follicle, sebaceous gland, and associated arrector pili muscle. In the embryo, the epidermis, hair, and glands form from the ectoderm, which is chemically influenced by the underlying mesoderm th ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Dermatology
Dermatology is the branch of medicine dealing with the skin.''Random House Webster's Unabridged Dictionary.'' Random House, Inc. 2001. Page 537. . It is a speciality with both medical and surgical aspects. A dermatologist is a specialist medical doctor who manages diseases related to skin, hair, nails, and some cosmetic problems. Etymology Attested in English in 1819, the word "dermatology" derives from the Greek δέρματος (''dermatos''), genitive of δέρμα (''derma''), "skin" (itself from δέρω ''dero'', "to flay") and -λογία '' -logia''. Neo-Latin ''dermatologia'' was coined in 1630, an anatomical term with various French and German uses attested from the 1730s. History In 1708, the first great school of dermatology became a reality at the famous Hôpital Saint-Louis in Paris, and the first textbooks (Willan's, 1798–1808) and atlases ( Alibert's, 1806–1816) appeared in print around the same time.Freedberg, et al. (2003). ''Fitzpatrick's Dermatology in ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Nail (anatomy)
A nail is a claw-like plate found at the tip of the Finger, fingers and Toe, toes on most primates. Nails correspond to the claws found in other animals. Fingernails and toenails are made of a tough protective protein called alpha-keratin, which is a polymer. Alpha-keratin is found in the hooves, claws, and horns of vertebrates. Structure The nail consists of the nail plate, the nail matrix and the nail bed below it, and the grooves surrounding it. Parts of the nail The matrix, sometimes called the ''matrix unguis'', keratogenous membrane, nail matrix, or onychostroma, is the active Tissue (biology), tissue (or Germ layer, germinal Matrix (biology), matrix) that generates cells, which harden as they move outward from the nail root to the nail plate. It is the part of the nail bed that is beneath the nail and contains nerves, lymph and blood vessels. The matrix produces cells that become the nail plate. The width and thickness of the nail plate is determined by the size, length, ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ectoderm
The ectoderm is one of the three primary germ layers formed in early embryonic development. It is the outermost layer, and is superficial to the mesoderm (the middle layer) and endoderm (the innermost layer). It emerges and originates from the outer layer of germ cells. The word ectoderm comes from the Greek ''ektos'' meaning "outside", and ''derma'' meaning "skin".Gilbert, Scott F. Developmental Biology. 9th ed. Sunderland, MA: Sinauer Associates, 2010: 333-370. Print. Generally speaking, the ectoderm differentiates to form epithelial and neural tissues (spinal cord, peripheral nerves and brain). This includes the skin, linings of the mouth, anus, nostrils, sweat glands, hair and nails, and tooth enamel. Other types of epithelium are derived from the endoderm. In vertebrate embryos, the ectoderm can be divided into two parts: the dorsal surface ectoderm also known as the external ectoderm, and the neural plate, which invaginates to form the neural tube and neural crest. Th ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ichthyosis
Ichthyosis is a family of genetic skin disorders characterized by dry, thickened, scaly skin. The more than 20 types of ichthyosis range in severity of symptoms, outward appearance, underlying genetic cause and mode of inheritance (e.g., dominant, recessive, autosomal or X-linked). Ichthyosis comes from the Greek ἰχθύς ''ichthys'', literally "fish", since dry, scaly skin is the defining feature of all forms of ichthyosis. The severity of symptoms can vary enormously, from the mildest, most common, types such as ichthyosis vulgaris, which may be mistaken for normal dry skin, up to life-threatening conditions such as harlequin-type ichthyosis. Ichthyosis vulgaris accounts for more than 95% of cases. Types Many types of ichthyoses exist, and an exact diagnosis may be difficult. Types of ichthyoses are classified by their appearance, if they are syndromic or not, and by mode of inheritance. For example, non-syndromic ichthyoses that are inherited recessively come under the um ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Allergic Contact Dermatitis
Allergic contact dermatitis (ACD) is a form of contact dermatitis that is the manifestation of an allergic response caused by contact with a substance; the other type being irritant contact dermatitis (ICD). Although less common than ICD, ACD is accepted to be the most prevalent form of immunotoxicity found in humans. By its allergic nature, this form of contact dermatitis is a hypersensitive reaction that is atypical within the population. The mechanisms by which these reactions occur are complex, with many levels of fine control. Their immunology centres on the interaction of immunoregulatory cytokines and discrete subpopulations of T lymphocytes. Signs and symptoms The symptoms of allergic contact dermatitis are very similar to the ones caused by irritant contact dermatitis, which makes the first even harder to diagnose. The first sign of allergic contact dermatitis is the presence of the rash or skin lesion at the site of exposure. Depending on the type of allergen causing it ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Raynaud Phenomenon
Raynaud syndrome, also known as Raynaud's phenomenon, eponymously named after the physician Auguste Gabriel Maurice Raynaud, who first described it in his doctoral thesis in 1862, is a medical condition in which the spasm of small arteries causes episodes of reduced blood flow to end arterioles. Typically, the fingers, and less commonly, the toes, are involved. Rarely, the nose, ears, or lips are affected. The episodes classically result in the affected part turning white and then blue. Often, numbness or pain occurs. As blood flow returns, the area turns red and burns. The episodes typically last minutes but can last several hours. Episodes are typically triggered by cold or emotional stress. Primary Raynaud's, also known as idiopathic, means that it is spontaneous, of unknown cause, and unrelated to another disease. Secondary Raynaud's occurs as a result of another condition and has an older age at onset; episodes are intensely painful and can be asymmetric and associated wi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Lichen Planus
Lichen planus (LP) is a chronic inflammatory and immune-mediated disease that affects the skin, nails, hair, and mucous membranes. It is not an actual lichen, and is only named that because it looks like one. It is characterized by polygonal, flat-topped, violaceous papules and plaques with overlying, reticulated, fine white scale ( Wickham's striae), commonly affecting dorsal hands, flexural wrists and forearms, trunk, anterior lower legs and oral mucosa. The hue may be gray-brown in people with darker skin. Although there is a broad clinical range of LP manifestations, the skin and oral cavity remain as the major sites of involvement. The cause is unknown, but it is thought to be the result of an autoimmune process with an unknown initial trigger. There is no cure, but many different medications and procedures have been used in efforts to control the symptoms. The term lichenoid reaction (lichenoid eruption or lichenoid lesion) refers to a lesion of similar or identical histopa ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Epidermolysis Bullosa
Epidermolysis bullosa (EB) is a group of rare medical conditions that result in easy blistering of the skin and mucous membranes. Blisters occur with minor trauma or friction and are painful. Its severity can range from mild to fatal. Inherited EB is a rare disease with a prevalence in the United States of 8.2 per million live births. Those with mild cases may not develop symptoms until they start to crawl or walk. Complications may include esophageal narrowing, squamous cell skin cancer, and the need for amputations. EB is due to a mutation in at least one of 16 different genes. Some types are autosomal dominant while others are autosomal recessive. The underlying mechanism is a defect in attachment between or within the layers of the skin. Loss or diminished function of C7 leads to weakness in the structural architecture of the dermal–epidermal junction (DEJ) and mucosal membranes. There are four main types: epidermolysis bullosa simplex (EBS), dystrophic epidermolysis bul ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Chromosome 20
Chromosome 20 is one of the 23 pairs of chromosomes in humans. Chromosome 20 spans around 66 million base pairs (the building material of DNA) and represents between 2 and 2.5 percent of the total DNA in cells. Chromosome 20 was fully sequenced in 2001 and was reported to contain over 59 million base pairs. Since then, due to sequencing improvements and fixes, the length of chromosome 20 has been updated to just over 66 million base pairs. Genes Number of genes The following are some of the gene count estimates of human chromosome 20. Because researchers use different approaches to genome annotation their predictions of the number of genes on each chromosome varies (for technical details, see gene prediction). Among various projects, the collaborative consensus coding sequence project ( CCDS) takes an extremely conservative strategy. So CCDS's gene number prediction represents a lower bound on the total number of human protein-coding genes. Gene list The following is a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
