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Aniridia
Aniridia is a condition characterized by the absence or near absence of the iris, the colored, muscular ring in the eye that controls the size of the pupil and regulates the amount of light entering the eye. This absence results in a primarily black appearance of the central eye. Aniridia can be congenital, typically affecting both eyes, or caused by a penetrant injury. Congenital aniridia is not simply an iris defect but a more complex condition affecting multiple parts of the eye, with macular and optic nerve hypoplasia, cataract, and corneal changes. Vision may be severely compromised and the disorder is frequently associated with several other ocular complications, including nystagmus, amblyopia, buphthalmos, and cataract. In some cases, aniridia occurs as part of a broader syndrome, like WAGR syndrome ( kidney nephroblastoma, genitourinary anomalies and intellectual disability) or Gillespie syndrome ( cerebellar ataxia). PAX6 The PAX6 gene, located within the AN2 ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
WAGR Syndrome
WAGR syndrome (also known as WAGR complex, Wilms tumour-aniridia syndrome, aniridia-Wilms tumour syndrome) is a rare genetic syndrome in which affected children are predisposed to develop Wilms' tumour (a tumour of the kidneys), aniridia (absence of the coloured part of the eye, the iris), genitourinary anomalies, and mental retardation. The "G" is sometimes instead given as " gonadoblastoma", since the genitourinary anomalies can include tumours of the gonads (testes or ovaries). Some WAGR syndrome patients show severe childhood obesity and hyperphagia, and are categorised as WAGRO (adding obesity) which may be associated with the coinciding loss of brain-derived neurotrophic factor (BDNF) a gene that is also on chromosome 11. The condition, first described by Miller et al. in 1964 in its association with other congenital malformations, results from a deletion on chromosome 11 resulting in the loss of several genes. As such, it is one of the best studied examples of a condi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Gillespie Syndrome
Gillespie syndrome, also called aniridia, cerebellar ataxia and mental deficiency, is a rare genetic disorder. The disorder is characterized by partial aniridia (meaning that part of the iris is missing), ataxia (motor and coordination problems), and, in most cases, intellectual disability. It is heterogeneous, inherited in either an autosomal dominant or autosomal recessive manner. Gillespie syndrome was first described by American ophthalmologist Fredrick Gillespie in 1965. Presentation The combination of muscular hypotonia and fixed dilated pupils in infancy is suspicious of Gillespie syndrome. Early onset partial aniridia, cerebellar ataxia, and mental retardation are hallmark of syndrome. The iris abnormality is specific and seems pathognomonic of Gillespie syndrome. The aniridia consisting of a superior coloboma and inferior iris hypoplasia, foveomacular dysplasia. Atypical Gillespie syndrome associated with bilateral ptosis, exotropia, correctopia, iris hypoplasia, anter ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Wilms Tumor
Wilms' tumor or Wilms tumor, also known as nephroblastoma, is a cancer of the kidneys that typically occurs in children (rarely in adults), and occurs most commonly as a renal tumor in child patients. It is named after Max Wilms, the German surgeon (1867–1918) who first described it. Approximately 650 cases are diagnosed in the U.S. annually. The majority of cases occur in children with no associated genetic syndromes; however, a minority of children with Wilms' tumor have a congenital abnormality. It is highly responsive to treatment, with about 90 percent of children being cured. Signs and symptoms Typical signs and symptoms of Wilms' tumor include the following: * a painless, palpable abdominal mass * loss of appetite * abdominal pain * fever * nausea and vomiting * Hematuria, blood in the urine (in about 20% of cases) * Hypertension, high blood pressure in some cases (especially if synchronous or metachronous bilateral kidney involvement) * Rarely as varicoceleErgin ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Macular Hypoplasia
Macular hypoplasia (or foveal hypoplasia) is a rare medical condition involving the underdevelopment of the macula, a small area on the retina (the eye's internal surface) responsible for seeing in detail and sensing light. Macular hypoplasia is often associated with albinism. When the foveal area of the eye is compromised, visual clarity and color perception are reduced. Diagnosing is done by an Ophthalmology, ophthalmologist. The foveal area of the eye is located in the back of the eyeball. It is placed in front of the optic nerve and is responsible for light sensory and visual perceptiveness. Other diseases with foveal hypoplasia besides albinism include aniridia, retinopathy of prematurity, and Alport syndrome. Causes Macular hypoplasia occurs the most in people that have a diagnosis of albinism. There are four gene mutations that occur in albinism and are linked to macular hypoplasia. The four mutations can occur on the phenotypes of FH, PAX6, SLC38A8, and AHR. The most com ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Autosomal Dominant
In genetics, dominance is the phenomenon of one variant (allele) of a gene on a chromosome masking or overriding the Phenotype, effect of a different variant of the same gene on Homologous chromosome, the other copy of the chromosome. The first variant is termed dominant and the second is called recessive. This state of having Heterozygosity, two different variants of the same gene on each chromosome is originally caused by a mutation in one of the genes, either new (''de novo'') or Heredity, inherited. The terms autosomal dominant or autosomal recessive are used to describe gene variants on non-sex chromosomes (autosomes) and their associated traits, while those on sex chromosomes (allosomes) are termed X-linked dominant, X-linked recessive or Y-linked; these have an inheritance and presentation pattern that depends on the sex of both the parent and the child (see Sex linkage). Since there is only one Y chromosome, Y-linked traits cannot be dominant or recessive. Additionally, ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Mutations
In biology, a mutation is an alteration in the nucleic acid sequence of the genome of an organism, virus, or extrachromosomal DNA. Viral genomes contain either DNA or RNA. Mutations result from errors during DNA or viral replication, mitosis, or meiosis or other types of damage to DNA (such as pyrimidine dimers caused by exposure to ultraviolet radiation), which then may undergo error-prone repair (especially microhomology-mediated end joining), cause an error during other forms of repair, or cause an error during replication ( translesion synthesis). Mutations may also result from substitution, insertion or deletion of segments of DNA due to mobile genetic elements. Mutations may or may not produce detectable changes in the observable characteristics (phenotype) of an organism. Mutations play a part in both normal and abnormal biological processes including: evolution, cancer, and the development of the immune system, including junctional diversity. Mutation is the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Iris (anatomy)
The iris (: irides or irises) is a thin, annular structure in the eye in most mammals and birds that is responsible for controlling the diameter and size of the pupil, and thus the amount of light reaching the retina. In optical terms, the pupil is the eye's aperture, while the iris is the diaphragm (optics), diaphragm. Eye color is defined by the iris. Etymology The word "iris" is derived from the Greek word for "rainbow", also Iris (mythology), its goddess plus messenger of the gods in the ''Iliad'', because of the many eye color, colours of this eye part. Structure The iris consists of two layers: the front pigmented Wikt:fibrovascular, fibrovascular layer known as a stroma of iris, stroma and, behind the stroma, pigmented epithelial cells. The stroma is connected to a sphincter muscle (sphincter pupillae), which contracts the pupil in a circular motion, and a set of dilator muscles (dilator pupillae), which pull the iris radially to enlarge the pupil, pulling it in folds. ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Heterozygous
Zygosity (the noun, zygote, is from the Greek "yoked," from "yoke") () is the degree to which both copies of a chromosome or gene have the same genetic sequence. In other words, it is the degree of similarity of the alleles in an organism. Most eukaryotes have two matching sets of chromosomes; that is, they are diploid. Diploid organisms have the same locus (genetics), loci on each of their two sets of homologous chromosomes except that the sequences at these loci may differ between the two chromosomes in a matching pair and that a few chromosomes may be mismatched as part of a chromosomal Sex-determination system#Chromosomal determination, sex-determination system. If both alleles of a diploid organism are the same, the organism is #Homozygous, homozygous at that locus. If they are different, the organism is #Heterozygous, heterozygous at that locus. If one allele is missing, it is #Hemizygous, hemizygous, and, if both alleles are missing, it is #Nullizygous, nullizygous. The ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Intellectual Disability
Intellectual disability (ID), also known as general learning disability (in the United Kingdom), and formerly mental retardation (in the United States), Rosa's Law, Pub. L. 111-256124 Stat. 2643(2010).Archive is a generalized neurodevelopmental disorder characterized by significant impairment in intellectual and adaptive functioning that is first apparent during childhood. Children with intellectual disabilities typically have an intelligence quotient (IQ) below 70 and deficits in at least two adaptive behaviors that affect everyday living. According to the DSM-5, intellectual functions include reasoning, problem solving, planning, abstract thinking, judgment, academic learning, and learning from experience. Deficits in these functions must be confirmed by clinical evaluation and individualized standard IQ testing. On the other hand, adaptive behaviors include the social, developmental, and practical skills people learn to perform tasks in their everyday lives. Deficits in ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
