Educalingo cookies are used to personalize ads and get web traffic statistics. We also share information about the use of the site with our social media, advertising and analytics partners. Meaning of "ipercromia" in the Italian dictionary. The definition of hyperchromia in the dictionary is an increase in skin pigmentation. Synonyms and antonyms of ipercromia in the Italian dictionary of synonyms.
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Descubra todo lo que Scribd tiene para ofrecer, incluyendo libros y audiolibros de importantes editoriales. A Compact Review. Balu Kamaraj and Rituraj Purohit. Correspondence should be addressed to Rituraj Purohit; riturajpurohit gmail.
Academic Editor: Raja Sivamani. Kamaraj and R. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
Oculocutaneous albinism OCA is an autosomal recessive disorder caused by either complete lack of or a reduction of melanin biosynthesis in the melanocytes. Also a locus has been mapped to the human chromosome 4q24 region which is responsible for genetic cause of OCA5.
In this paper, we summarized the clinical and molecular features of OCA genes. Further, we reviewed the screening of pathological mutations of OCA genes and its molecular mechanism of the protein upon mutation by in silico approach. It is observed that the pathological genetic mutations and their structural and functional significance of OCA genes will aid in development of personalized medicine for albinism patients.
Albinism is a group of disorders caused by reduction of poly- meric pigment melanin [ 1 ]. Melanin production is closely regulated in the body and occurs in specialized ectodermal derived cells called melanocytes. Generally, melanocytes are possibly cutaneous hair, skin or extracutaneous eye, cochlea which derived from different ectodermal lineages. The terms albinism, oculocutaneous albinism OCA , and ocular albinism OA can be used both as a phenotypic descriptions and as references to specific syndromes.
Sir Arcibald Garrod initially states albinism as an inborn error of metabolism [ 2 , 3 ], but it is now believed to be a heterogeneous genetic disorder caused by mutations in several different genes. Population studies have shown a genetic heterogeneity with evidence pointing to several loci [ 3 ]. Oculocutaneous albinism OCA is a heterogeneous and autosomal recessive disorder. Apart from these four genes, other genes are also involved to cause OCA.
However, until recently, no pathological mutations of these genes are reported in human OCA patients [ 6 — 9 ]. Very recently, two new OCA genes are found. Mutations of C10orf11 gene are identified in a family from the Faroe Islands and in a Lithuanian patient [ 10 ]. In addition, an OCA locus is mapped to 4q24 in a consanguineous Pakistani family, but the gene has not yet been described [ 12 ].
Many polymorphisms have not been experimentally illustrated in terms of their possible disease association. BioMed Research International. In this study we elucidate the molecular basis of OCA disorder caused by disease-associated mutations. Further we have highlighted a better understanding of the relationships between genetic and phenotypic variation as well as protein structure and function.
Our review data further helps in the field of pharmacogenomics to develop a personalized medicine for OCA-associated disorders. Albinism affects one in 20, individuals worldwide, but the prevalence of individual subtypes varies among different ethnic backgrounds [ 13 ]. This is primarily due to an OCA2 found deletion seen at high frequencies within this population [ 16 — 19 ]. In general all types of albinism have some lack of pigmen- tation, but the amount is different depending on the type.
OCA1 causes complete absence of pigment in the skin, hair, and eyes, but some individuals may have some degree of pigmentation. OCA1 also affects reduced visual acuity, pho- tophobia sensitivity to light , and nystagmus involuntary eye movement. OCA2 causes a minimal to moderate degree of pigmentation in the hair, skin, and eyes.
OCA3 has been difficult to identify based on appearance alone. It has been clearly noticeable when a very light-skinned child is born to dark-skinned parents. Ocular albinism affects only the eyes, causing minimal pigmentation. Difficulty controlling eye movements, reduced visual acuity, and nystagmus may occur [ 21 ].
OCA6 and OCA7 genes associated with albinism shows the classic visual symptoms and signs but without an obvious change in the pigmentation patterns [ 10 , 11 ]. Genes Associated with Oculocutaneous Albinism. TYR gene consists of 5 exons spanning about 65 kb of genomic DNA which encodes a protein called tyrosinase and consist of amino acids [ 23 ]. TYR EC 1. Table 1: Mutations detected for albinism associated genes. Source: human gene mutation database, 05 Dec, ; ND: not determined.
Mutations completely abol- ishing tyrosinase activity result in OCA1A, while mutations rendering some enzyme activity result in OCA1B allowing some accumulation of melanin pigment over time. Almost mutations in TYR are known [ 25 ] Table 1. Type 1 temperature sensitive oculocutaneous albinism OCA1-TS is an extremely rare form of OCA1 characterized by the production of temperature sensitive tyrosinase pro- teins leading to dark hair on the legs, arms, and chest cooler body areas and white hair on the scalp, axilla, and pubic area warmer body areas.
It is highly polymorphic [ 27 ] and is suspected to play an important role in human pigmentation [ 28 — 30 ]. This gene encodes P protein, a kDa integral melanoso- mal protein with 12 predicted transmembrane domains and consists of amino acids [ 27 , 31 , 32 ]. The P protein acts as a precursor to melanin synthesis, within the melanocyte, and serves as a key control point at which ethnic skin colour variation is determined.
Moreover, it may stabilize or traffic the melanosomal protein such as tyrosinase which regulate melanosomal pH or serve as a melanosomal tyrosine transporter [ 26 , 33 — 36 ]. Due to mutation, P protein might disturb the pigmentation charac- teristics via altering the melanosomal tyrosine or tyrosinase bioavailability or function.
OCA3 is mostly caused by the genetic mutation. OCA3 is also known as Rufous oculocutaneous albinism. Tyrp1 is involved in the maintenance of melanosome structure and affects melanocyte proliferation and cell death [ 43 — 46 ]. Tyrp1 shows tyrosine hydroxylase activity, albeit under low substrate L-tyrosine concentration, but no DOPA oxidase activity [ 47 , 48 ].
It is an essential cofactor for tyrosinase activity [ 49 ]. Tyrp1 has also been attributed with various other catalytic functions including dopachrome tautomerase Dct , dihydroxyindole DHI oxidase [ 50 ], and 5,6-dihydroxyindolecarboxylic acid DHICA [ 51 ]. To date, 16 mutations were found in TYRP1 gene which is.
Mutations in the membrane-associated trans-. It is expressed in melanosomal cell lines [ 53 , 54 ]. The function of SLC45A2 is still unknown, but studies from Medaka fish show that the SLC45A2 protein plays an important role in pigmentation and probably functions as a membrane transporter in melanosomes [ 53 ]. Japanese, and Korean OCA patients [ 20 , 55 — 57 ]. SLC24A5 and C10orf Mutations in SLC24A5 encode. SLC24A5 gene was located in the chromosomal position of 15q SLC24A5 mutations were detected in patients of diverse ethnic origins, thus indicating that OCA6 is not restricted to the Chinese population.
It is evident that the cutaneous phenotype was. Prominently, Thr is present in almost all individuals of European American origin, while Ala is present in African Asian populations. Thr is associated with lighter pigmented skin, thus suggesting an important role of this SNP in the establishment of human pigmentation [ 61 ]. Recent results indicate a role of SLC24A5 in the maturation of melanosomes. The assembly of SLC24A5 into melanosomes showed an important role for the melanosomal architecture and to ensure that melanin is synthesized properly.
Hence, the lack of SLC24A5 may impair or disrupt melanosomal maturation and melanin biosynthesis [ 11 ]. C10orf11 was located in the chromosomal position of 10q The family of LRRs-containing proteins encompasses members with a variety of functions, including cell adhesion and signalling, extracellular-matrix assembly, neuronal development, and RNA processing [ 62 ].
The updated mutation list of these genes was shown in Table 1. This disease is caused by mutation. Pigment of the skin and hair is normal or only slightly diluted. Human eyes are severely affected with reduced visual acuity and photophobia. Strabismus or nystagmus is frequently affected with OA1. The fundus and irides are depigmented.
BLOC1S6, respectively, and their updated mutations lists. The disease can affect the dysfunctions. The major severe form. The disorder is more common in Puerto Rico [ 66 ], where it affects approximately 1 in 1, individuals [ 67 ].
The decrease in phagocytosis results. The eye, skin, and hair pigment is reduced. Quantitative and. Molecular dyamics. Figure 1: Flow chart of OCA 1—4 gene analysis. CHS1 gene provides. Scientists believe that this protein plays. Lysosomes act as recycling cen-. Digestive enzymes are used to break down toxic substances, digest bacteria that invade the cell, and recycle worn-out cell components. Due to the presence of huge amount of variations data, experimental study of each variant cannot be achieved in.
Therefore, predictive analysis of the. Further, it helps to observe the structural and functional changes of protein upon mutation at atomic level.
The strategy of our investigation is depicted in Figure 1.
Meaning of "ipercromia" in the Italian dictionary
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