Treacher Collins syndrome
Treacher Collins syndrome - this is purely genetically dependent disease, which is a subspecies of the common family illnesses, dysostosis: congenital disorders in the development of bone structures.The word dysostosis imply underdevelopment and disturbed ossification of bone tissue, especially those at embryogenesis arise from connective prototypes.In the case of Treacher Collins syndrome is formed dysostosis skull bones.And the number of these clinical manifestations depends on the expressiveness of the disease (the number of embedded clinical manifestations that are sure to show up).
Treacher Collins syndrome - this is quite rare.Its frequency is 1 in 50,000 newborns.In addition, this syndrome is characterized by a favorable prognostic criteria for the subsequent life of these patients are not disturbed mental development, and small stages of development they can continue to maintain an active social life.The big threat is severe stage Treacher Collins syndrome - when they have a child virtually no face, and the disease is severe deformity, which is completely cut off the child from society.
Treacher Collins syndrome causes
Treacher Collins syndrome is an autosomal - dominant disease.This means that the defective gene of the disease is not associated with sex chromosome, which means that you may receive is equivalent to both men and women.In addition, this gene is dominant, which means that when present in the organism, Treacher Collins syndrome manifest 100% of the presence of this gene.
Thus, the development of the disease Treacher Collins does not depend on the impact of any adverse external and internal factors.We can say that the disease is already built into the genetic code of the child and begins to unfold long before his birth.
The cause of Treacher Collins syndrome in the newborn child lies still at the stage of embryogenesis and fetal organs of bookmarks.At this particular time, but rather at the 7th week of embryonic development, there is a mutation in a particular human chromosome genetic code - 5 chromosome.This is the longest chromosome in the human genome, and it is responsible for the synthesis of the material for the future skeleton.As a result, in this particular chromosome mutation occurs - the so-called "nonsense mutation".The peculiarity of this mutation lies in the peculiarities of intracellular protein synthesis.Normally, such an important process as the protein biosynthesis takes place as follows: the DNA strand "rewrites" the information on the auxiliary unit - RNA.Literally speaking RNA cloned, recording the specific sequence of DNA.These areas are defined sequence of nucleotides components, each of which bears its own particular information.But in addition, there are specific nucleotide genes, which are called "stop codons".These genes perform a specific function - in the subsequent assembly of the protein-based RNA they complete the construction of the protein molecule.
After RNA will be created with the full information similar to maternal DNA, it is transported to the organ-specific cellular ribosome.That it deals with the future of synthesizing protein - the basis of the cell structure of certain organs.RNA passed through the ribosome, and more specifically through its functional regions.These sites interact with RNA "reads" information from it and produce the protein chains, each of which corresponds to its nucleotide RNA.However, when the functional facility communicates with the above-described gene stop codon, it receives information about the termination of protein synthesis.Speaking in his own words, stop codons, as it were "cut off" from the total weight of the individual polypeptide chains, where each has its own structure.Later these chains will be assembled into the protein molecules.
But Treacher Collins syndrome in the 5th chromosome in its gene called TCOF1 crashes - in place of the normal nucleotides capable of creating a polypeptide chain formed by a stop codon.As a result, a further synthesis causes premature termination assembly protein and a protein obtained defective.As a result, developing a syndrome haploinsufficiency - the amount of protein formed when a failure is simply not enough to synthesize the future prototype facial bone structure of the skull and then the proper development of his bone structure itself.
As a consequence, the formation of a number of developing facial deformities of the skull: a violation of the proportions of its bony part, atresia (hypoplasia) of ears and ear canal, complete or partial violation of the formation of regular features.
Treacher Collins syndrome manifestations
Treacher Collins syndrome is a huge amount of clinical symptoms, and very often there is only one patient of these symptoms.The disease is congenital, but rather, even embryonic, and thus, the first signs of Treacher Collins syndrome can be seen even when a newborn into the world.
main clinical syndrome of the disease - a multiple deformities of the facial skeleton.One of the most striking manifestations of the normal form is a violation of the optic fissure.This symptom outer corner of the eye is not directed up as normal and down.Moreover, such a demonstration will be observed on both sides.It will also form a triangular shaped defects century - the so-called coloboma.Also
violation eye shape will be present underdeveloped cheekbones.Typically, Treacher Collins syndrome, they are very small, which leads to disruption of facial symmetry.In addition to the zygomatic bone is broken and the development of the zygomatic process of the temporal bone and the mandible.The lower jaw is small and gives the face a peculiar kind of sick, like a bird's beak.In addition to the defect of the lower jaw can also develop soft tissue defects of the oral region and form excessively wide mouth slit.Sometimes these defects can also add the splitting of the upper sky, better known as "cleft palate".
also involve major changes and dental formula: with Treacher Collins syndrome, underdeveloped molars and the teeth are widely separated each other, which causes a significant malocclusion.
third striking feature of the disease is hypoplasia or absence of the ears and ear canal.The ears may not be fully be distorted (aplasia) and formed the so-called "false ears."With regard to the ear canal, the most frequently observed him hypoplasia - atresia, resulting in children with the syndrome are deaf.
Treacher Collins syndrome can have three levels: beginner, intermediate and heavy.At the initial stage there are only some minor and often hypoplasia of facial bones.At an average (the most common form) are underdeveloped external auditory canal, a small lower jaw, the deformation and asymmetry of the facial bones and a malfunction of the optic fissure.In severe all of the above changes will become severe, visually in children with this form and virtually no discern all features.
Treacher Collins syndrome treatment
Since Treacher Collins syndrome is a congenital disease and the main reason for its development is a genetic strain in the period of development of the embryo, the treatment aimed directly at the elimination of this gene defect does not exist.The only treatment currently used Treacher Collins syndrome is a purely surgical and involves the surgical removal of a manifestation of the disease: multiple bone defects.
Running plastic external auditory canal and the ear correction.When cases, where there is a cleft palate - hold her surgery.
also in severe cases of congenital disease is a strong underdevelopment of the lower jaw, in which it becomes very small, compared with the normal size.But the dimensions of language are normal.As a result, the language simply does not fit into a pathologically small jaw and can sink, causing suffocation of the child.Therefore, in order to prevent possible suffocation when the tongue with the Treacher Collins syndrome is often carried out the following operational benefits: the epiglottis is removed and installed a permanent tracheostomy.
is important to understand that the treatment of Treacher Collins syndrome is a complex multi-step process and includes a number of plastic surgery.A complete cycle of treatment of the disease can take several years, if not decades.The main principle of such treatment: a stepwise, gradual removal and correction of defects.In some cases, the complete removal of the defect is impossible and palliative surgery performed - surgical interventions to improve and facilitate the patient's life.