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Exencephaly
Exencephaly is a type of cephalic disorder wherein the brain is located outside of the skull. This condition is usually found in embryos as an early stage of anencephaly. As an exencephalic pregnancy progresses, the neural tissue gradually degenerates. The prognosis for infants born with exencephaly is extremely poor. It is rare to find an infant born with exencephaly, as most cases that are not early stages of anencephaly are usually stillborn. Those infants who are born with the condition usually die within hours or minutes. Caused by the failure of cranial neuropore to properly fuse, between the 3rd and 4th week post conception. The calvarium doesn't develop/fuse properly, therefore the brain extrudes from the cranium. Pathophysiology Until recently, the medical literature did not indicate a connection among many genetic disorders, both genetic syndromes and genetic diseases, that are now being found to be related. As a result of new genetic research, some of these are, in fact ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cephalic Disorder
Cephalic disorders () are congenital conditions that stem from damage to, or abnormal development of, the budding nervous system. Cephalic disorders are not necessarily caused by a single factor, but may be influenced by hereditary or genetic conditions, nutritional deficiencies, or by environmental exposures during pregnancy, such as medication taken by the mother, maternal infection, or exposure to radiation. Some cephalic disorders occur when the cranial sutures (the fibrous joints that connect the bones of the skull) join prematurely. Most cephalic disorders are caused by a disturbance that occurs very early in the development of the fetal nervous system. The human nervous system develops from a small, specialized plate of cells on the surface of the embryo. Early in development, this plate of cells forms the neural tube, a narrow sheath that closes between the third and fourth weeks of pregnancy to form the brain and spinal cord of the embryo. Four main processes are resp ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cell (biology)
The cell is the basic structural and functional unit of life forms. Every cell consists of a cytoplasm enclosed within a membrane, and contains many biomolecules such as proteins, DNA and RNA, as well as many small molecules of nutrients and metabolites.Cell Movements and the Shaping of the Vertebrate Body in Chapter 21 of Molecular Biology of the Cell '' fourth edition, edited by Bruce Alberts (2002) published by Garland Science. The Alberts text discusses how the "cellular building blocks" move to shape developing s. It is also common ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Retinopathy
Retinopathy is any damage to the retina of the eyes, which may cause vision impairment. Retinopathy often refers to retinal vascular disease, or damage to the retina caused by abnormal blood flow. Age-related macular degeneration is technically included under the umbrella term retinopathy but is often discussed as a separate entity. Retinopathy, or retinal vascular disease, can be broadly categorized into proliferative and non-proliferative types. Frequently, retinopathy is an ocular manifestation of systemic disease as seen in diabetes or hypertension. Diabetes is the most common cause of retinopathy in the U.S. as of 2008. Diabetic retinopathy is the leading cause of blindness in working-aged people. It accounts for about 5% of blindness worldwide and is designated a priority eye disease by the World Health Organization. Signs and symptoms Many people often do not have symptoms until very late in their disease course. Patients often become symptomatic when there is irreversibl ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Meckel–Gruber Syndrome
Meckel-Gruber syndrome is a rare, lethal ciliopathic genetic disorder, characterized by renal cystic dysplasia, central nervous system malformations (occipital encephalocele), polydactyly (postaxial), hepatic developmental defects, and pulmonary hypoplasia due to oligohydramnios. Meckel–Gruber syndrome is named for Johann Meckel and Georg Gruber. Pathophysiology Meckel–Gruber syndrome (MKS) is an autosomal recessive lethal malformation. Recently, two MKS genes, MKS1 and MKS3, have been identified. A study done recently has described the cellular, sub-cellular and functional characterization of the novel proteins, MKS1 and meckelin, encoded by these genes. The malfunction of this protein production is mainly responsible for this lethal disorder. Relation to other rare genetic disorders Recent findings in genetic research have suggested that a large number of genetic disorders, both genetic syndromes and genetic diseases, that were not previously identified in the me ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Alström Syndrome
Alström syndrome (AS), also called Alström–Hallgren syndrome, is a very rare autosomal recessive genetic disorder characterised by childhood obesity and multiple organ dysfunction. Symptoms include early-onset type 2 diabetes, cone-rod dystrophy resulting in blindness, sensorineural hearing loss and dilated cardiomyopathy. Endocrine disorders typically also occur, such as hypergonadotrophic hypogonadism and hypothyroidism, as well as acanthosis nigricans resulting from hyperinsulinemia. Developmental delay is seen in almost half of people with Alström syndrome. It is caused by mutations in the gene '' ALMS1'', which is involved in the formation of cellular cilia, making Alström syndrome a ciliopathy. At least 239 disease-causing mutations in ''ALMS1'' have been described . Alström syndrome is sometimes confused with Bardet–Biedl syndrome, another ciliopathy which has similar symptoms, but Bardet–Biedl syndrome tends to have later onset in its symptoms, includ ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Nephronophthisis
Nephronophthisis is a genetic disorder of the kidneys which affects children. It is classified as a medullary cystic kidney disease. The disorder is inherited in an autosomal recessive fashion and, although rare, is the most common genetic cause of childhood kidney failure. It is a form of ciliopathy. Its incidence has been estimated to be 0.9 cases per million people in the United States, and 1 in 50,000 births in Canada. Signs and symptoms Infantile, juvenile, and adolescent forms of nephronophthisis have been identified. Although the range of characterizations is broad, people affected by nephronophthisis typically present with polyuria (production of a large volume of urine), polydipsia (excessive liquid intake), and after several months to years, end-stage kidney disease, a condition necessitating either dialysis or a kidney transplant in order to survive. Some individuals with nephronophthisis also have so-called "extra-renal symptoms" which can include tapetoretinal degenera ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Polycystic Liver Disease
Polycystic liver disease (PLD) usually describes the presence of multiple cysts scattered throughout normal liver tissue. PLD is commonly seen in association with autosomal-dominant polycystic kidney disease, with a prevalence of 1 in 400 to 1000, and accounts for 8–10% of all cases of end-stage renal disease. The much rarer autosomal-dominant polycystic liver disease will progress without any kidney involvement. Presentation Pathophysiology Associations with '' PRKCSH'' and ''SEC63'' have been described. Polycystic liver disease comes in two forms: autosomal dominant polycystic kidney disease (with kidney cysts) and autosomal dominant polycystic liver disease (liver cysts only). Diagnosis Most patients with PLD are asymptomatic with simple cysts found following routine investigations. After confirming the presence of cysts in the liver, laboratory tests may be ordered to check for liver function including bilirubin, alkaline phosphatase, alanine aminotransferase, and prothrombi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Polycystic Kidney Disease
Polycystic kidney disease (PKD or PCKD, also known as polycystic kidney syndrome) is a genetic disorder in which the renal tubules become structurally abnormal, resulting in the development and growth of multiple cysts within the kidney. These cysts may begin to develop in utero, in infancy, in childhood, or in adulthood. Cysts are non-functioning tubules filled with fluid pumped into them, which range in size from microscopic to enormous, crushing adjacent normal tubules and eventually rendering them non-functional as well. PKD is caused by abnormal genes that produce a specific abnormal protein; this protein has an adverse effect on tubule development. PKD is a general term for two types, each having their own pathology and genetic cause: autosomal dominant polycystic kidney disease (ADPKD) and autosomal recessive polycystic kidney disease (ARPKD). The abnormal gene exists in all cells in the body; as a result, cysts may occur in the liver, seminal vesicles, and pancreas. T ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Bardet–Biedl Syndrome
Bardet–Biedl syndrome (BBS) is a ciliopathic human genetic disorder that produces many effects and affects many body systems. It is characterized by rod/cone dystrophy, polydactyly, central obesity, hypogonadism, and kidney dysfunction in some cases. Historically, slower mental processing has also been considered a principal symptom but is now not regarded as such. Signs and symptoms Bardet–Biedl syndrome is a pleiotropic disorder with variable expressivity and a wide range of clinical variability observed both within and between families. The most common clinical features are rod–cone dystrophy, with childhood-onset night-blindness followed by increasing visual loss; postaxial polydactyly; truncal obesity that manifests during infancy and remains problematic throughout adulthood; varying degrees of learning disabilities; male hypogenitalism and complex female genitourinary malformations; and renal dysfunction, a major cause of morbidity and mortality. There is a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Primary Ciliary Dyskinesia
Primary ciliary dyskinesia (PCD) is a rare, autosomal recessive genetic ciliopathy, that causes defects in the action of cilia lining the upper and lower respiratory tract, sinuses, Eustachian tube, middle ear, Fallopian tube, and flagella of sperm cells. The alternative name of "immotile ciliary syndrome" is no longer favored as the cilia do have movement, but are merely inefficient or unsynchronized. When accompanied by situs inversus the condition is known as Kartagener syndrome. Respiratory epithelial motile cilia, which resemble microscopic "hairs" (although structurally and biologically unrelated to hair), are complex organelles that beat synchronously in the respiratory tract, moving mucus toward the throat. Normally, cilia beat 7 to 22 times per second, and any impairment can result in poor mucociliary clearance, with subsequent upper and lower respiratory infection. Cilia also are involved in other biological processes (such as nitric oxide production), currently the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Pleiotropic
Pleiotropy (from Greek language, Greek , 'more', and , 'way') occurs when one gene influences two or more seemingly unrelated Phenotype, phenotypic traits. Such a gene that exhibits multiple phenotypic expression is called a pleiotropic gene. Mutation in a pleiotropic gene may have an effect on several traits simultaneously, due to the gene coding for a product used by a myriad of cells or different targets that have the same signaling function. Pleiotropy can arise from several distinct but potentially overlapping mechanisms, such as gene pleiotropy, developmental biology, developmental pleiotropy, and selectional pleiotropy. Gene pleiotropy occurs when a gene product interacts with multiple other proteins or catalyzes multiple reactions. Developmental pleiotropy occurs when mutations have multiple effects on the resulting phenotype. Selectional pleiotropy occurs when the resulting phenotype has many effects on fitness (biology), fitness (depending on factors such as age and ge ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Human
Humans (''Homo sapiens'') are the most abundant and widespread species of primate, characterized by bipedalism and exceptional cognitive skills due to a large and complex brain. This has enabled the development of advanced tools, culture, and language. Humans are highly social and tend to live in complex social structures composed of many cooperating and competing groups, from families and kinship networks to political states. Social interactions between humans have established a wide variety of values, social norms, and rituals, which bolster human society. Its intelligence and its desire to understand and influence the environment and to explain and manipulate phenomena have motivated humanity's development of science, philosophy, mythology, religion, and other fields of study. Although some scientists equate the term ''humans'' with all members of the genus ''Homo'', in common usage, it generally refers to ''Homo sapiens'', the only Extant taxon, extant member. A ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
