Warsaw breakage syndrome | |
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Other names | WABS [1] |
Warsaw breakage syndrome (Warsaw syndrome, WABS) is a rare genetic condition. Fewer than 10 cases have been reported by 2018. [2] Its clinical manifestations affect several organ systems, and includes microcephaly and severe growth retardation among others.
Israeli Health Ministry describes the condition manifestation as "characterized by smaller than average head circumference (microcephaly) as early as the embryonic stage, intrauterine growth restriction (IUGR) as well as postnatal growth restriction (dwarfism). Furthermore, patients born with this condition experience hearing impairments, moderate to significant developmental delays, skeletal disorders and heart disorders (40%), as well as disorders to various body systems such as the renal and urogenital systems. In some patients, blood tests indicate increased chromosome fragility. Some fetuses die in utero (intrauterine fetal demise)." [5]
This condition is caused by mutations in the DDX11 gene. [4] [6]
DDX11 mutation that causes WABS is described at US National Library of Medicine: [7]
The DDX11 gene provides instructions for making an enzyme called ChlR1. This enzyme functions as a helicase. Helicases are enzymes that attach (bind) to DNA and temporarily unwind the two spiral strands (double helix) of the DNA molecule. This unwinding is necessary for copying (replicating) DNA in preparation for cell division, and for repairing damaged DNA and any errors that are made when DNA is copied. In addition, after DNA is copied, ChlR1 plays a role in ensuring proper separation of each chromosome during cell division. By helping repair errors in DNA and ensuring proper DNA replication, the ChlR1 enzyme is involved in maintaining the stability of a cell's genetic information. DDX11 gene mutations severely reduce or completely eliminate ChlR1 enzyme activity. As a result, the enzyme cannot bind to DNA and cannot unwind the DNA strands to help with DNA replication and repair. A lack of functional ChlR1 impairs cell division and leads to an accumulation of DNA damage. This DNA damage can appear as breaks in the DNA, giving the condition its name. It is unclear how these problems in DNA maintenance lead to the specific abnormalities characteristic of Warsaw breakage syndrome.
This gene encodes an iron-sulfur containing DNA helicase that belongs to the Fe–S DNA helicases. [3] This protein interacts with the 9-1-1 checkpoint complex protein.[ citation needed ]
The inheritance pattern is autosomal recessive. [2] [5] Condition is very rare, but its prevalence in Ashkenazi Jews population is about 1/50. [5] [7]
The DDX should be based on the following:[ citation needed ]
There is no known curative treatment for this condition presently. Management is supportive. [4]
This condition was first described in 2010. [8]
Microcephaly 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. Brain development is often affected; people with this disorder often have an intellectual disability, poor motor function, poor speech, abnormal facial features, seizures and dwarfism.
Helicases are a class of enzymes thought to be vital to all organisms. Their main function is to unpack an organism's genetic material. Helicases are motor proteins that move directionally along a nucleic acid phosphodiester backbone, separating two hybridized nucleic acid strands, using energy from ATP hydrolysis. There are many helicases, representing the great variety of processes in which strand separation must be catalyzed. Approximately 1% of eukaryotic genes code for helicases.
A pre-replication complex (pre-RC) is a protein complex that forms at the origin of replication during the initiation step of DNA replication. Formation of the pre-RC is required for DNA replication to occur. Complete and faithful replication of the genome ensures that each daughter cell will carry the same genetic information as the parent cell. Accordingly, formation of the pre-RC is a very important part of the cell cycle.
RecQ helicase is a family of helicase enzymes initially found in Escherichia coli that has been shown to be important in genome maintenance. They function through catalyzing the reaction ATP + H2O → ADP + P and thus driving the unwinding of paired DNA and translocating in the 3' to 5' direction. These enzymes can also drive the reaction NTP + H2O → NDP + P to drive the unwinding of either DNA or RNA.
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Seckel syndrome, or microcephalic primordial dwarfism is an extremely rare congenital nanosomic disorder. Inheritance is autosomal recessive. It is characterized by intrauterine growth restriction and postnatal dwarfism with a small head, narrow bird-like face with a beak-like nose, large eyes with down-slanting palpebral fissures, receding mandible and intellectual disability.
RAPADILINO syndrome is an autosomal recessive disorder characterized by:
Uncombable hair syndrome (UHS) is a rare structural anomaly of the hair with a variable degree of effect. It is characterized by hair that is silvery, dry, frizzy, wiry, and impossible to comb. It was first reported in the early 20th century. It typically becomes apparent between the ages of 3 months and 12 years. UHS has several names, including "pili trianguli et canaliculi," "cheveux incoiffables," and "spun-glass hair." This disorder is believed to be autosomal recessive in most instances, but there are a few documented cases where multiple family members display the trait in an autosomal dominant fashion. Based on the current scientific studies related to the disorder, the three genes that have been causally linked to UHS are PADI3, TGM3, and TCHH. These genes encode proteins important for hair shaft formation. Clinical symptoms of the disorder arise between 3 months and 12 years of age. The quantity of hair on the head does not change, but hair starts to grow more slowly and becomes increasingly "uncombable." To be clinically apparent, 50% of all scalp hair shafts must be affected by UHS. This syndrome only affects the hair shaft of the scalp and does not influence hair growth in terms of quantity, textural feel, or appearance on the rest of the body.
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Twinkle protein also known as twinkle mtDNA helicase is a mitochondrial protein that in humans is encoded by the TWNK gene located in the long arm of chromosome 10 (10q24.31).
Probable ATP-dependent RNA helicase DDX11 is an enzyme that in humans is encoded by the DDX11 gene.
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