|
Compound Heterozygote
In medical genetics, compound heterozygosity is the condition of having two or more heterogeneous recessive alleles at a particular locus that can cause genetic disease in a heterozygous state; that is, an organism is a compound heterozygote when it has two recessive alleles for the same gene, but with those two alleles being different from each other (for example, both alleles might be mutated but at different locations). Compound heterozygosity reflects the diversity of the mutation base for many autosomal recessive genetic disorders; mutations in most disease-causing genes have arisen many times. This means that many cases of disease arise in individuals who have two unrelated alleles, who technically are heterozygotes, but both the alleles are defective. These disorders are often best known in some classic form, such as the homozygous recessive case of a particular mutation that is widespread in some population. In its compound heterozygous forms, the disease may have lower pene ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Medical Genetics
Medical genetics is the branch tics in that human genetics is a field of scientific research that may or may not apply to medicine, while medical genetics refers to the application of genetics to medical care. For example, research on the causes and inheritance of genetic disorders would be considered within both human genetics and medical genetics, while the diagnosis, management, and counselling people with genetic disorders would be considered part of medical genetics. In contrast, the study of typically non-medical phenotypes such as the genetics of eye color would be considered part of human genetics, but not necessarily relevant to medical genetics (except in situations such as albinism). ''Genetic medicine'' is a newer term for medical genetics and incorporates areas such as gene therapy, personalized medicine, and the rapidly emerging new medical specialty, predictive medicine. Scope Medical genetics encompasses many different areas, including clinical practice ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Metabolism
Metabolism (, from el, μεταβολή ''metabolē'', "change") is the set of life-sustaining chemical reactions in organisms. The three main functions of metabolism are: the conversion of the energy in food to energy available to run cellular processes; the conversion of food to building blocks for proteins, lipids, nucleic acids, and some carbohydrates; and the elimination of metabolic wastes. These enzyme-catalyzed reactions allow organisms to grow and reproduce, maintain their structures, and respond to their environments. The word metabolism can also refer to the sum of all chemical reactions that occur in living organisms, including digestion and the transportation of substances into and between different cells, in which case the above described set of reactions within the cells is called intermediary (or intermediate) metabolism. Metabolic reactions may be categorized as '' catabolic'' – the ''breaking down'' of compounds (for example, of glucose to pyruvate ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Hemoglobin C
Hemoglobin C (abbreviated as HbC) is an abnormal hemoglobin in which glutamic acid residue at the 6th position of the β-globin chain is replaced with a lysine residue due to a point mutation in the '' HBB'' gene. People with one copy of the gene for hemoglobin C do not experience symptoms, but can pass the abnormal gene on to their children. Those with two copies of the gene are said to have hemoglobin C disease and can experience mild anemia. It is possible for a person to have both the gene for hemoglobin S (the form associated with sickle cell anemia) and the gene for hemoglobin C; this state is called hemoglobin SC disease, and is generally more severe than hemoglobin C disease, but milder than sickle cell anemia. HbC was discovered by Harvey Itano and James V. Neel in 1950 in two African-American families. It has since been established that it is most common among people in West Africa. It confers survival benefits as individuals with HbC are naturally resistant to malari ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Allele
An allele (, ; ; modern formation from Greek ἄλλος ''állos'', "other") is a variation of the same sequence of nucleotides at the same place on a long DNA molecule, as described in leading textbooks on genetics and evolution. ::"The chromosomal or genomic location of a gene or any other genetic element is called a locus (plural: loci) and alternative DNA sequences at a locus are called alleles." The simplest alleles are single nucleotide polymorphisms (SNP). but they can also be insertions and deletions of up to several thousand base pairs. Popular definitions of 'allele' typically refer only to different alleles within genes. For example, the ABO blood grouping is controlled by the ABO gene, which has six common alleles (variants). In population genetics, nearly every living human's phenotype for the ABO gene is some combination of just these six alleles. Most alleles observed result in little or no change in the function of the gene product it codes for. Howeve ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Hemoglobin
Hemoglobin (haemoglobin BrE) (from the Greek word αἷμα, ''haîma'' 'blood' + Latin ''globus'' 'ball, sphere' + ''-in'') (), abbreviated Hb or Hgb, is the iron-containing oxygen-transport metalloprotein present in red blood cells (erythrocytes) of almost all vertebrates (the exception being the fish family Channichthyidae) as well as the tissues of some invertebrates. Hemoglobin in blood carries oxygen from the respiratory organs (''e.g.'' lungs or gills) to the rest of the body (''i.e.'' tissues). There it releases the oxygen to permit aerobic respiration to provide energy to power functions of an organism in the process called metabolism. A healthy individual human has 12to 20grams of hemoglobin in every 100mL of blood. In mammals, the chromoprotein makes up about 96% of the red blood cells' dry content (by weight), and around 35% of the total content (including water). Hemoglobin has an oxygen-binding capacity of 1.34mL O2 per gram, which increases the total blood oxy ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Sickle Cell-beta Thalassemia
Sickle cell-beta thalassemia is an inherited blood disorder. The disease may range in severity from being relatively benign and like sickle cell trait to being similar to sickle cell disease. Signs and symptoms Patients with sickle cell-beta thalassemia may present with painful crises similar to patients with sickle cell disease Cause Sickle cell-beta thalassemia is caused by inheritance of a sickle cell allele from one parent and a beta thalassemia allele from the other. Mutations A sickle allele is always the same mutation of the beta-globin gene (glutamic acid to valine at amino acid six). In contrast, beta-thalassemia alleles can be created by many different mutations including both deletion and non-deletion forms. Diagnosis Patient may present with symptomatic anemia or with sickle crises. In the United States and other countries with new-born screening programs, the disease may be identified in neonates. Diagnostic tests include DNA sequencing, hemoglobin ele ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Sickle Cell
Sickle cell disease (SCD) is a group of blood disorders typically inherited from a person's parents. The most common type is known as sickle cell anaemia. It results in an abnormality in the oxygen-carrying protein haemoglobin found in red blood cells. This leads to a rigid, sickle-like shape under certain circumstances. Problems in sickle cell disease typically begin around 5 to 6 months of age. A number of health problems may develop, such as attacks of pain (known as a sickle cell crisis), anemia, swelling in the hands and feet, bacterial infections and stroke. Long-term pain may develop as people get older. The average life expectancy in the developed world is 40 to 60 years. Sickle cell disease occurs when a person inherits two abnormal copies of the β-globin gene (''HBB'') that makes haemoglobin, one from each parent. This gene occurs in chromosome 11. Several subtypes exist, depending on the exact mutation in each haemoglobin gene. An attack can be set off by tempera ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Phenylketonuria
Phenylketonuria (PKU) is an inborn error of metabolism that results in decreased metabolism of the amino acid phenylalanine. Untreated PKU can lead to intellectual disability, seizures, behavioral problems, and mental disorders. It may also result in a musty smell and lighter skin. A baby born to a mother who has poorly treated PKU may have heart problems, a small head, and low birth weight. Phenylketonuria is an inherited genetic disorder. It is due to mutations in the '' PAH'' gene, which results in low levels of the enzyme phenylalanine hydroxylase. This results in the buildup of dietary phenylalanine to potentially toxic levels. It is autosomal recessive, meaning that both copies of the gene must be mutated for the condition to develop. There are two main types, classic PKU and variant PKU, depending on whether any enzyme function remains. Those with one copy of a mutated gene typically do not have symptoms. Many countries have newborn screening programs for the diseas ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Sandhoff Disease
Sandhoff disease is a lysosomal genetic, lipid storage disorder caused by the inherited deficiency to create functional beta-hexosaminidases A and B. These catabolic enzymes are needed to degrade the neuronal membrane components, ganglioside GM2, its derivative GA2, the glycolipid globoside in visceral tissues, and some oligosaccharides. Accumulation of these metabolites leads to a progressive destruction of the central nervous system and eventually to death. The rare autosomal recessive neurodegenerative disorder is clinically almost indistinguishable from Tay–Sachs disease, another genetic disorder that disrupts beta-hexosaminidases A and S. There are three subsets of Sandhoff disease based on when first symptoms appear: classic infantile, juvenile and adult late onset. Symptoms and signs Sandhoff disease symptoms are clinically indeterminable from Tay–Sachs disease. The classic infantile form of the disease has the most severe symptoms and is incredibly hard to diagnose at t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
GM2-gangliosidosis, AB Variant
GM2-gangliosidosis, AB variant is a rare, autosomal recessive metabolic disorder that causes progressive destruction of nerve cells in the brain and spinal cord. It has a similar pathology to Sandhoff disease and Tay–Sachs disease. The three diseases are classified together as the GM2 gangliosidoses, because each disease represents a distinct molecular point of failure in the activation of the same enzyme, beta-hexosaminidase. AB variant is caused by a failure in the gene that makes an enzyme cofactor for beta-hexosaminidase, called the GM2 activator. Symptoms and signs Signs and symptoms of GM2-gangliosidosis, AB variant are identical with those of infantile Tay–Sachs disease, except that enzyme assay testing shows normal levels of hexosaminidase A. Infantile Sandhoff disease has similar symptoms and prognosis, except that there is deficiency of both hexosaminidase A and hexosaminidase B. Infants with this disorder typically appear normal until the age of 3 to 6 months, ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Tay–Sachs Disease
Tay–Sachs disease is a genetic disorder that results in the destruction of nerve cells in the brain and spinal cord. The most common form is infantile Tay–Sachs disease, which becomes apparent around three to six months of age, with the baby losing the ability to turn over, sit, or crawl. This is then followed by seizures, hearing loss, and inability to move, with death usually occurring by the age of three to five. Less commonly, the disease may occur in later childhood or adulthood (juvenile or late-onset). These forms tend to be less severe, but the juvenile form typically results in death by age 15. Tay–Sachs disease is caused by a genetic mutation in the ''HEXA'' gene on chromosome 15, which codes form a subunit of the hexosaminidase enzyme known as hexosaminidase A. It is inherited from a person's parents in an autosomal recessive manner. The mutation disrupts the activity of the enzyme, which results in the build-up of the molecule GM2 ganglioside within cells, ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Single Point Of Failure
A single point of failure (SPOF) is a part of a system that, if it fails, will stop the entire system from working. SPOFs are undesirable in any system with a goal of high availability or reliability, be it a business practice, software application, or other industrial system. Overview Systems can be made robust by adding redundancy in all potential SPOFs. Redundancy can be achieved at various levels. The assessment of a potential SPOF involves identifying the critical components of a complex system that would provoke a total systems failure in case of malfunction. Highly reliable systems should not rely on any such individual component. For instance, the owner of a small tree care company may only own one woodchipper. If the chipper breaks, he may be unable to complete his current job and may have to cancel future jobs until he can obtain a replacement. The owner of the tree care company may have spare parts ready for the repair of the wood chipper, in case it fails. ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
