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Tetrasomy 18p
Tetrasomy 18p is a genetic condition that is caused by the presence of an isochromosome composed of two copies of the short arm of chromosome 18 in addition to the two normal copies of the chromosome. It is characterized by multiple medical and developmental concerns. Signs and symptoms Tetrasomy 18p causes a wide range of medical and developmental problems.Sebold C, Roeder E, Zimmerman M, Soileau B, Heard P, Carter E, Schatz M, White WA, Perry B, Reinker K, O'Donnell L, Lancaster J, Li J, Hasi M, Hill A, Pankratz L, Hale DE, Cody JD (2010). Tetrasomy 18p: report of the molecular and clinical findings of 43 individuals. Am J Med Genet 152A(9): 2164-72. Congenital anomalies Cardiac anomalies are the most common congenital malformation in individuals with tetrasomy 18p. However, there is no pathognomatic heart defect associated with the condition. Patent ductus arteriosus is the most common defect. Septal defects (ventricular septal defects and atrial septal defects) are a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Isochromosome
An isochromosome is an unbalanced structural abnormality in which the arms of the chromosome are mirror images of each other. The chromosome consists of two copies of either the long (q) arm or the short (p) arm because isochromosome formation is equivalent to a simultaneous duplication and deletion of genetic material. Consequently, there is partial trisomy of the genes present in the isochromosome and partial monosomy of the genes in the lost arm. Nomenclature An isochromosome can be abbreviated as i(chromosome number)(centromeric breakpoint). For example, an isochromosome of chromosome 17 containing two q arms can be identified as i(17)(q10).(Medulloblastoma) Mechanism Isochromosomes can be created during mitosis and meiosis through a misdivision of the centromere or U-type strand exchange. Centromere misdivision Under normal separation of sister chromatids in anaphase, the centromere will divide longitudinally, or parallel to the long axis of the chromosome. An isoch ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Rocker Bottom Feet
Unlike the flexible flat foot that is commonly encountered in young children, congenital vertical talus is characterized by presence of a very rigid foot deformity. The foot deformity in congenital vertical talus consists of various components, namely a prominent calcaneus caused by the ankle equines or plantar flexion, a convex and rounded sole of the foot caused by prominence of the head of the talus, and a dorsiflexion and abduction of the forefoot and midfoot on the hindfoot. It gets its name from the foot's resemblance to the bottom of a rocking chair. There are two subcategories of congenital vertical talus namely idiopathic or isolated type and non-idiopathic type which may be seen in association with arthrogryposis multiplex congenital, genetic syndromes and other neuromuscular disorders. It can be associated with Edwards' syndrome (trisomy 18), Patau syndrome (trisomy 13), Trisomy 9 and mutation in the gene HOXD10. Treatment The treatment of congenital vertical talus can b ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Developmental Disabilities
Developmental disability is a diverse group of chronic conditions, comprising mental or physical impairments that arise before adulthood. Developmental disabilities cause individuals living with them many difficulties in certain areas of life, especially in "language, mobility, learning, self-help, and independent living".Center for Disease Control and Prevention. (2013)Developmental disabilities.Retrieved October 18, 2013 Developmental disabilities can be detected early on and persist throughout an individual's lifespan. Developmental disability that affects all areas of a child's development is sometimes referred to as global developmental delay. The most common developmental disabilities are: * Motor disorders, and learning difficulties such as dyslexia, Tourette's syndrome, dyspraxia, dysgraphia, Irlen syndrome, and dyscalculia. * Autism and Asperger syndrome are a series of conditions called autistic spectrum disorders that causes difficulties in communications. Autistic ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Mosaic (genetics)
Mosaicism or genetic mosaicism is a condition in multicellular organisms in which a single organism possesses more than one genetic line as the result of genetic mutation. This means that various genetic lines resulted from a single fertilized egg. Genetic mosaics may often be confused with chimerism, in which two or more genotypes arise in one individual similarly to mosaicism. In chimerism, though, the two genotypes arise from the fusion of more than one fertilized zygote in the early stages of embryonic development, rather than from a mutation or chromosome loss. Genetic mosaicism can result from many different mechanisms including chromosome nondisjunction, anaphase lag, and endoreplication. Anaphase lagging is the most common way by which mosaicism arises in the preimplantation embryo. Mosaicism can also result from a mutation in one cell during development, in which case the mutation will be passed on only to its daughter cells (and will be present only in certain adult ce ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Small Supernumerary Marker Chromosome
A small supernumerary marker chromosome (sSMC) is an abnormal extra chromosome. It contains copies of parts of one or more normal chromosomes and like normal chromosomes is located in the cell's nucleus, is replicated and distributed into each daughter cell during cell division, and typically has genes which may be expressed. However, it may also be active in causing birth defects and neoplasms (e.g. tumors and cancers). The sSMC's small size makes it virtually undetectable using classical cytogenetic methods: the far larger DNA and gene content of the cell's normal chromosomes obscures those of the sSMC. Newer molecular techniques such as fluorescence in situ hybridization, next generation sequencing, comparative genomic hybridization, and highly specialized cytogenetic G banding analyses are required to study it. Using these methods, the DNA sequences and genes in sSMCs are identified and help define as well as explain any effect(s) it may have on individuals. Human cells t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Microcephaly
Microcephaly (from New Latin ''microcephalia'', from Ancient Greek μικρός ''mikrós'' "small" and κεφαλή ''kephalé'' "head") is a medical condition involving a smaller-than-normal head. Microcephaly may be present at birth or it may develop in the first few years of life. Since brain growth is correlated with head growth, people with this disorder often have an intellectual disability, poor motor function, poor speech, abnormal facial features, seizures and dwarfism. The disorder is caused by a disruption to the genetic processes that form the brain early in pregnancy, though the cause is not identified in most cases. Many genetic syndromes can result in microcephaly, including chromosomal and single-gene conditions, though almost always in combination with other symptoms. Mutations that result solely in microcephaly (primary microcephaly) exist but are less common. External toxins to the embryo, such as alcohol during pregnancy or vertically transmitted infec ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Seizure
An epileptic seizure, informally known as a seizure, is a period of symptoms due to abnormally excessive or synchronous neuronal activity in the brain. Outward effects vary from uncontrolled shaking movements involving much of the body with loss of consciousness ( tonic-clonic seizure), to shaking movements involving only part of the body with variable levels of consciousness (focal seizure), to a subtle momentary loss of awareness ( absence seizure). Most of the time these episodes last less than two minutes and it takes some time to return to normal. Loss of bladder control may occur. Seizures may be provoked and unprovoked. Provoked seizures are due to a temporary event such as low blood sugar, alcohol withdrawal, abusing alcohol together with prescription medication, low blood sodium, fever, brain infection, or concussion. Unprovoked seizures occur without a known or fixable cause such that ongoing seizures are likely. Unprovoked seizures may be exacerbated by stress or sl ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Hypertonia
Hypertonia is a term sometimes used synonymously with spasticity and rigidity in the literature surrounding damage to the central nervous system, namely upper motor neuron lesions. Impaired ability of damaged motor neurons to regulate descending pathways gives rise to disordered spinal reflexes, increased excitability of muscle spindles, and decreased synaptic inhibition. These consequences result in abnormally increased muscle tone of symptomatic muscles. Some authors suggest that the current definition for spasticity, the velocity-dependent over-activity of the stretch reflex, is not sufficient as it fails to take into account patients exhibiting increased muscle tone in the absence of stretch reflex over-activity. They instead suggest that "reversible hypertonia" is more appropriate and represents a treatable condition that is responsive to various therapy modalities like drug and/or physical therapy. Presentation Symptoms associated with central nervous systems disorders ar ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Hypotonia
Hypotonia is a state of low muscle tone (the amount of tension or resistance to stretch in a muscle), often involving reduced muscle strength. Hypotonia is not a specific medical disorder, but a potential manifestation of many different diseases and disorders that affect motor nerve control by the brain or muscle strength. Hypotonia is a lack of resistance to passive movement, whereas muscle weakness results in impaired active movement. Central hypotonia originates from the central nervous system, while peripheral hypotonia is related to problems within the spinal cord, peripheral nerves and/or skeletal muscles. Severe hypotonia in infancy is commonly known as floppy baby syndrome. Recognizing hypotonia, even in early infancy, is usually relatively straightforward, but diagnosing the underlying cause can be difficult and often unsuccessful. The long-term effects of hypotonia on a child's development and later life depend primarily on the severity of the muscle weakness and the na ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Growth Hormone Deficiency
Growth hormone deficiency (GHD), or human growth hormone deficiency, is a medical condition resulting from not enough growth hormone (GH). Generally the most noticeable symptom is that an individual attains a short height. Newborns may also present low blood sugar or a small penis size. In adults there may be decreased muscle mass, high cholesterol levels, or poor bone density. GHD can be present at birth or develop later in life. Causes may include genetics, trauma, infections, tumors, or radiation therapy. Genes that may be involved include GH1, GHRHR, or BTK. In a third of cases no cause is apparent. The underlying mechanism generally involves problems with the pituitary gland. Some cases are associated with a lack of other pituitary hormones, in which case it is known as combined pituitary hormone deficiency. Diagnosis involves blood tests to measure growth hormone levels. Treatment is by growth hormone replacement using synthetic human growth hormone. The frequency ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Reflux
Reflux is a technique involving the condensation of vapors and the return of this condensate to the system from which it originated. It is used in industrial and laboratory distillations. It is also used in chemistry to supply energy to reactions over a long period of time. Reflux in industrial distillation The term ''reflux'' is very widely used in industries that utilize large-scale distillation columns and fractionators such as petroleum refineries, petrochemical and chemical plants, and natural gas processing plants. In that context, reflux refers to the portion of the overhead liquid product from a distillation column or fractionator that is returned to the upper part of the column as shown in the schematic diagram of a typical industrial distillation column. Inside the column, the downflowing reflux liquid provides cooling and condensation of the upflowing vapors thereby increasing the efficiency of the distillation column. The more reflux provided for a given numbe ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Constipation
Constipation is a bowel dysfunction that makes bowel movements infrequent or hard to pass. The stool is often hard and dry. Other symptoms may include abdominal pain, bloating, and feeling as if one has not completely passed the bowel movement. Complications from constipation may include hemorrhoids, anal fissure or fecal impaction. The normal frequency of bowel movements in adults is between three per day and three per week. Babies often have three to four bowel movements per day while young children typically have two to three per day. Constipation has many causes. Common causes include slow movement of stool within the colon, irritable bowel syndrome, and pelvic floor disorders. Underlying associated diseases include hypothyroidism, diabetes, Parkinson's disease, celiac disease, non-celiac gluten sensitivity, colon cancer, diverticulitis, and inflammatory bowel disease. Medications associated with constipation include opioids, certain antacids, calcium channel blockers, ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
