|
Chromosome Instability Syndrome
Chromosome instability syndromes are a group of inherited conditions associated with chromosomal instability and breakage. They often lead to an increased tendency to develop certain types of malignancies. The following chromosome instability syndromes are known: * Ataxia telangiectasia * Ataxia telangiectasia-like disorder * Bloom syndrome * Fanconi anaemia * Nijmegen breakage syndrome Neurodegenerative diseases Chromosome instability syndromes include several inherited neurodegenerative diseases that are due to mutations in genes that encode enzymes necessary for DNA repair. Epigenetic alterations often occur in association with the DNA repair defect, and such alterations likely have a role in the etiology of the disease. Chromosome instability syndromes due to impaired DNA repair and with features of neurodegeneration and epigenetic alteration were summarized by Bernstein and Bernstein. These syndromes include Aicardi-Goutieres syndrome, amyotrophic lateral sclerosis, a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Chromosome Instability
Chromosomal instability (CIN) is a type of genomic instability in which chromosomes are unstable, such that either whole chromosomes or parts of chromosomes are duplicated or deleted. More specifically, CIN refers to the increase in rate of addition or loss of entire chromosomes or sections of them. The unequal distribution of DNA to daughter cells upon mitosis results in a failure to maintain euploidy (the correct number of chromosomes) leading to aneuploidy (incorrect number of chromosomes). In other words, the daughter cells do not have the same number of chromosomes as the cell they originated from. Chromosomal instability is the most common form of genetic instability and cause of aneuploidy. These changes have been studied in solid tumors (a tumor that usually doesn't contain liquid, pus, or air, compared to liquid tumor), which may or may not be cancerous. CIN is a common occurrence in solid and haematological cancers, especially colorectal cancer. Although many tumours sho ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cockayne Syndrome
Cockayne syndrome (CS), also called Neill-Dingwall syndrome, is a rare and fatal autosomal recessive neurodegenerative disorder characterized by growth failure, impaired development of the nervous system, abnormal sensitivity to sunlight (photosensitivity), eye disorders and premature aging.Bender M, Potocki L, Metry D. What syndrome is this? Cockayne syndrome. Pediatric Dermatology erial online November 2003;20(6):538-540. Available from: MEDLINE with Full Text, Ipswich, MA. Accessed April 30, 2015. Failure to thrive and neurological disorders are criteria for diagnosis, while photosensitivity, hearing loss, eye abnormalities, and cavities are other very common features. Problems with any or all of the internal organs are possible. It is associated with a group of disorders called leukodystrophies, which are conditions characterized by degradation of neurological white matter. The underlying disorder is a defect in a DNA repair mechanism. Unlike other defects of DNA repair, pati ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Germline
In biology and genetics, the germline is the population of a multicellular organism's cells that pass on their genetic material to the progeny (offspring). In other words, they are the cells that form the egg, sperm and the fertilised egg. They are usually differentiated to perform this function and segregated in a specific place away from other bodily cells. As a rule, this passing-on happens via a process of sexual reproduction; typically it is a process that includes systematic changes to the genetic material, changes that arise during recombination, meiosis and fertilization for example. However, there are many exceptions across multicellular organisms, including processes and concepts such as various forms of apomixis, autogamy, automixis, cloning or parthenogenesis. The cells of the germline are called germ cells. For example, gametes such as a sperm and an egg are germ cells. So are the cells that divide to produce gametes, called gametocytes, the cells that produce thos ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Premature Ovarian Failure
Primary ovarian insufficiency (POI) (also called premature ovarian insufficiency, premature menopause, and premature ovarian failure) is the partial or total loss of reproductive and hormonal function of the ovaries before age 40 because of folliclular (egg producing area) dysfunction or early loss of eggs. POI can be seen as part of a continuum of changes leading to menopause that differ from age-appropriate menopause in the age of onset, degree of symptoms, and sporadic return to normal ovarian function. POI affects approximately 1 in 10,000 women under age 20, 1 in 1,000 women under age 30, and 1 in 100 of those under age 40. A medical triad for the diagnosis is amenorrhea, hypergonadotropism, and hypoestrogenism. Physical and emotional symptoms include hot flashes, night sweats, dry skin, vaginal dryness, irregular or absent menstruation, anxiety, depression, mental fog, irritability, nervousness, decreased libido, and increased autoimmune disruption. The sense of shoc ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Homologous Recombination
Homologous recombination is a type of genetic recombination in which genetic information is exchanged between two similar or identical molecules of double-stranded or single-stranded nucleic acids (usually DNA as in cellular organisms but may be also RNA in viruses). Homologous recombination is widely used by cells to accurately DNA repair harmful breaks that occur on both strands of DNA, known as double-strand breaks (DSB), in a process called homologous recombinational repair (HRR). Homologous recombination also produces new combinations of DNA sequences during meiosis, the process by which eukaryotes make gamete cells, like sperm and egg cells in animals. These new combinations of DNA represent genetic variation in offspring, which in turn enables populations to adapt during the course of evolution. Homologous recombination is also used in horizontal gene transfer to exchange genetic material between different strains and species of bacteria and viruses. Horizontal ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
MCM8
DNA replication licensing factor MCM8 is a protein that in humans is encoded by the ''MCM8'' gene. The protein encoded by this gene is one of the highly conserved mini-chromosome maintenance proteins (MCM) that are essential for the initiation of eukaryotic genome replication. The hexameric protein complex formed by the MCM proteins is a key component of the pre-replication complex (pre_RC) and may be involved in the formation of replication forks and in the recruitment of other DNA replication related proteins. This protein contains the central domain that is conserved among the MCM proteins. This protein has been shown to co-immunoprecipitate with MCM4, 6 and 7, which suggests that it may interact with other MCM proteins and play a role in DNA replication. Alternatively spliced transcript variants encoding distinct isoforms have been described. DNA repair MCM8-deficient mice are defective in gametogenesis and display genome instability due to impaired homologous recombination. ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Xeroderma Pigmentosum
Xeroderma pigmentosum (XP) is a genetic disorder in which there is a decreased ability to repair DNA damage such as that caused by ultraviolet (UV) light. Symptoms may include a severe sunburn after only a few minutes in the sun, freckling in sun-exposed areas, dry skin and changes in skin pigmentation. Nervous system problems, such as hearing loss, poor coordination, loss of intellectual function and seizures, may also occur. Complications include a high risk of skin cancer, with about half having skin cancer by age 10 without preventative efforts, and cataracts. There may be a higher risk of other cancers such as brain cancers. XP is autosomal recessive, with mutations in at least nine specific genes able to result in the condition. Normally, the damage to DNA which occurs in skin cells from exposure to UV light is repaired by nucleotide excision repair. In people with xeroderma pigmentosum, this damage is not repaired. As more abnormalities form in DNA, cells malfunction and e ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Trichothiodystrophy
Trichothiodystrophy (TTD) is an autosomal recessive inherited disorder characterised by brittle hair and intellectual impairment. The word breaks down into ''tricho'' – "hair", '' thio'' – "sulphur", and ''dystrophy'' – "wasting away" or literally "bad nourishment". TTD is associated with a range of symptoms connected with organs of the ectoderm and neuroectoderm. TTD may be subclassified into four syndromes: Approximately half of all patients with trichothiodystrophy have photosensitivity, which divides the classification into syndromes with or without photosensitivity; BIDS and PBIDS, and IBIDS and PIBIDS. Modern covering usage is TTD-P (photosensitive), and TTD. Presentation Features of TTD can include photosensitivity, ichthyosis, brittle hair and nails, intellectual impairment, decreased fertility and short stature. A more subtle feature associated with this syndrome is a "tiger tail" banding pattern in hair shafts, seen in microscopy under polarized light. The acronyms ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Spinocerebellar Ataxia Type 1
Spinocerebellar ataxia type 1 (SCA1) is a rare autosomal dominant disorder, which, like other spinocerebellar ataxias, is characterized by neurological symptoms including dysarthria, hypermetric saccades, and ataxia of gait and stance. This cerebellar dysfunction is progressive and permanent. First onset of symptoms is normally between 30 and 40 years of age, though juvenile onset can occur. Death typically occurs within 10 to 30 years from onset. SCA1 is typically inherited from the parents in an autosomal dominant regime; the children of a person with the disease have a 50% chance of inheriting it themselves, and new mutations can occur in some cases. It is caused by an expanded number of trinucleotide repeats in the polyglutamine tract of the ''ATXN1'' gene, which encodes the ataxin 1 protein. This expansion results in a larger than normal number of repeats of the nucleotide sequence cytosine, adenine, guanine, or CAG, in the gene which, in turn, results in a larger than nor ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Huntington's Disease
Huntington's disease (HD), also known as Huntington's chorea, is a neurodegenerative disease that is mostly inherited. The earliest symptoms are often subtle problems with mood or mental abilities. A general lack of coordination and an unsteady gait often follow. It is also a basal ganglia disease causing a hyperkinetic movement disorder known as chorea. As the disease advances, uncoordinated, involuntary body movements of chorea become more apparent. Physical abilities gradually worsen until coordinated movement becomes difficult and the person is unable to talk. Mental abilities generally decline into dementia. The specific symptoms vary somewhat between people. Symptoms usually begin between 30 and 50 years of age but can start at any age. The disease may develop earlier in each successive generation. About eight percent of cases start before the age of 20 years, and are known as ''juvenile HD'', which typically present with the slow movement symptoms of Parkinson's d ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Friedrich's Ataxia
Friedreich's ataxia (FRDA or FA) is an autosomal-recessive genetic disease that causes difficulty walking, a loss of sensation in the arms and legs, and impaired speech that worsens over time. Symptoms generally start between 5 and 20 years of age. Many develop hypertrophic cardiomyopathy and require a mobility aid such as a cane, walker, or wheelchair in their teens. As the disease progresses, some affected people lose their sight and hearing. Other complications may include scoliosis and diabetes mellitus. The condition is caused by mutations in the ''FXN'' gene on chromosome 9, which makes a protein called frataxin. In FRDA, cells produce less frataxin. Degeneration of nerve tissue in the spinal cord causes the ataxia; particularly affected are the sensory neurons essential for directing muscle movement of the arms and legs through connections with the cerebellum. The spinal cord becomes thinner, and nerve cells lose some myelin sheath. No effective treatment is ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Fragile X Syndrome
Fragile X syndrome (FXS) is a genetic disorder characterized by mild-to-moderate intellectual disability. The average IQ in males with FXS is under 55, while about two thirds of affected females are intellectually disabled. Physical features may include a long and narrow face, large ears, flexible fingers, and large testicles. About a third of those affected have features of autism such as problems with social interactions and delayed speech. Hyperactivity is common, and seizures occur in about 10%. Males are usually more affected than females. This disorder and finding of Fragile X syndrome has an X-linked dominant inheritance. It is typically caused by an expansion of the CGG triplet repeat within the ''FMR1'' (fragile X messenger ribonucleoprotein 1) gene on the X chromosome. This results in silencing ( methylation) of this part of the gene and a deficiency of the resultant protein (FMRP), which is required for the normal development of connections between neurons. Diagno ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
.jpg "Click for more on -> Huntington's Disease")
