Angelman's syndrome – the genetic disease which is characterized by existence of neurologic symptomatology, a delay of mental development. It is shown by intellectual lag, weak formation of the speech, skills of sitting and walking, the chaotic movements, a hyperactivity, symptomatic epilepsy, causeless fun and laughter, scoliosis, a peculiar gait. Patients have special appearance: the mouth is large, teeth are located seldom, the chin is given forward. The diagnosis is established on the basis of clinical yielded, results of the genetic analysis. Specific treatment is absent, symptomatic therapy is carried out, psychological and pedagogical assistance is given.
The syndrome is called by last name the British pediatrician Mr. Angelman. In 1965 he the first described symptoms of a disease and called it "a syndrome of a happy puppet" as patients reminded him the hero of the picture "Boy puppet". Those years methods of genetic researches were not developed yet, it was impossible to establish the pathology reason. In 1987 researchers defined an etiology of a disease and renamed it into Angelman's syndrome. Now this term is official, but it is possible to meet synonymous names – "a syndrome of a puppet", "the Parsley syndrome", "a syndrome of a happy doll". Prevalence makes 1 case on 10-20 thousand newborns. The disease comes to light after the first year of life (sometimes – by 3-7 years), boys are ill more often.
Factors of development of a syndrome of Angelman continue to be investigated. Genetic defect is found in the 15th chromosome of maternal set, but its nature and a way of emergence can differ. Sometimes the disease debuts as a result of transfer of the changed genetic information from the parent, sometimes is a consequence of spontaneous violations in a genome. Chromosomal anomalies manage to be defined approximately at 85-88% of patients. Can be the cause of a syndrome:
- Deletion. At this defect a part of genetic material is lost or inactivated. Extensive deletion of area 15q12 of a chromosome in which the gene activator is localized are diagnosed for 70% of patients.
- One-parental disomiya. HORDES is defined in 2-3% of cases of a disease. At a set of chromosomes there are two copies of the 15th chromosome of the father. There is no maternal chromosome, the gene is also absent.
- Defect of imprinting. The essence of anomaly is that the center of imprinting regulating activity of a locus of UBE3A is nonfunctional, "switched off". The gene remains structurally whole, but does not perform the functions. Prevalence of DZ – 3-5%.
- UBE3A mutation. At 5-10% of patients mutational changes of a gene are an etiology. They are presented by inversions, mikrodeletion, translocations and duplications.
Basis of a syndrome of Angelman – violation of functions of a gene of UBE3A located in the fifteenth maternal chromosome. This gene codes production of a protein of E6AP which represents a fermental component of difficult reaction of degradation of proteins. E6AP participates in process of formation of an ubikvitin – a squirrel of system proteasy, stimulating defective proteinaceous molecules in brain neurons. Normal marks unnecessary (inactive, nonfunctional) proteins for the purpose of initiation of their destruction. E6AP provides fixing of an ubikvitin on a surface of a molecule of protein target. Then proteasoma split it on the peptide remains and on amino acids. At Angelman's syndrome is not fixed on defective proteins, they crowd in nervous tissue of a brain, process of synoptic transfer is broken. Deviations, delays in mental and motor development are formed.
Clinically the disease is shown aged from 6 up to 12 months. Gradually the arrest of development accrues, earlier mastered skills remain, but acquisition of new happens slowly. Children are able to sit, creep, take objects and to shift them from a hand in a hand, to support visual contact, to babble and murmur. Walking troubles, the sense of equilibrium is broken, frequent falling, bruises about furniture are observed. The tremor and the chaotic movements by extremities, especially hands comes to light. Speech frustration are presented both by delays, and total absence of the expressional speech. Children or do not speak at all, or use babble, simple syllables and words with a total amount no more than 10 units. The understanding of the turned speech, aspiration to communication, use of nonverbal means of communication remains: gestures, a mimicry, the mediated signs.
The main behavioural violation – a hyperactivity. Children have often fun and laugh without the objective reason, are dvigatelno stirred up, restless, are not purposeful. Many have a pathological attachment to a certain toy or a household item at which emergence the mood increases at once, the capriciousness and crying are replaced by laughter. Concentration of attention is reduced, a pereklyuchayemost bystry and not directed. There are difficulties of training, permanent decrease in intellectual functions. Easily stereotypies are fixed: rocking of a body, swinging hands. At 80% of patients the mikrotsefaliya, insufficient volume of a cranium, epileptic activity of a brain is noted. Decrease in control of movements of language which is shown by difficulties of sucking of a breast or a pacifier, the subsequent lack of body weight is seldom observed.
Characteristics of appearance of children – squint, a skoliotichesky curvature of a backbone, increase in teeth and lips, discharge of a tooth alignment, flattening of a nape, a vystupaniye forward a chin. It is often put out tongue, the mouth is slightly opened in a smile. Muscular dystonia develops, expressiveness of reflexes of sinews increases, forming specificity of motility: patients go on the direct not bent legs, shoulders raise, hands bend in elbows. A peculiar symptom – thirst for water. Most of children feel more quietly in the water environment, they like to lap in a bathroom, to play with ships in a basin.
Angelman's syndrome – a rare little-known disease. In this regard diagnosis and rendering the medico-psychology and pedagogical help are often carried out out of time, by 6-8 years that causes low success of correctional and medical actions. Without physiotherapeutic treatment violations of the musculoskeletal device are aggravated – patients suffer from severe forms of scoliosis, independently move hardly. The originality of appearance and behavior becomes the reason of deterioration in already complicated social adaptation. Everything listed involves weighting of an invalidization of patients.
With suspicion on Angelman's syndrome neurologists, psychiatrists and geneticists are engaged in inspection of children. Parents show complaints to lack of the speech, motive stereotypies, difficulties of formation of walking and other movement skills, a hyperactivity. Differential diagnostics during which more widespread diseases, such as intellectual backwardness, frustration of an autistic range, dementia, a mutizm, not symptomatic forms of epilepsy have to be excluded is carried out. The complex research includes the following procedures:
- General survey. Often point peculiar features of appearance of patients to existence of a syndrome: put out tongue, a salivation, a large mouth, wide rare teeth, the lower jaw acting forward, a flat shape of a nape. The light shade of skin, an eye and a hair is characteristic. Gait of children reminds the movements of a doll puppet because of strengthening of tendinous reflexes and decrease in a muscular tone.
- Survey by the psychiatrist. In 100% of cases of a syndrome of Angelman the expressed delay in development of mentality, lack of the independent speech or very poor lexicon is diagnosed. Communication is carried out by means of a mimicry, gestures, drawings. In behavior the hyperactivity, the stereotypic movements by hands, causeless laughter is noted.
- Neurologic inspection. At all patients the ataxy and a tremor of extremities is defined. 80% of patients have a post-natal mikrotsefaliya – a circle of the head of the newborn less than 32 cm, by 12 months – about 42 cm. According to EEG symptomatic epilepsy (high-amplitude categories of slow complex waves) comes to light, convulsive attacks are clinically possible. Some children have a squint, diffusion decrease in a muscular tone, strengthening of tendinous reflexes, giperkineza.
- Genetic research. Laboratory diagnostics is aimed at identification of mutations and deletion in UBE3A gene. The complex of procedures including fluorescent hybridization of in situ, the analysis of a mutation of the center of imprinting, region SA/PVS DNA methylation, diagnostics of a deletion by method of the micromatrix analysis, search of mutational changes in UBE3A locus is consistently carried out.
Treatment of a syndrome of Angelman
The chromosomal violations which are the cornerstone of a syndrome cannot be eliminated. To patients symptomatic treatment, psychology and pedagogical correction, rehabilitation actions is appointed. For reduction of frequency of epileptic seizures antikonvulsant, for normalization of a dream – melatonin are used. Occupations and sessions massage are aimed by medical physical culture at the development of small motility and the coordinated gait, elimination of scoliosis. For improvement of communicative skills of children train in a sign language, involve in group occupations, will organize sessions of the behavioural therapy allowing to master rules of interaction in society.
Search of ways of effective treatment of a syndrome continues. Test use of medicines on genetically modified mice is carried out. Results prove that inhibitors of a topoizomeraza are capable to activate a maternal gene of UBE3A. At this stage control researches are carried out, safety and risks of therapy is defined, but information is still not enough for transferring of experiments on groups of people.
Forecast and prevention
Expressiveness of symptoms of a syndrome of Angelman can strongly differ. Patients with easy forms of a disease have the favorable forecast: their speech becomes more developed, skills of self-checking at some violations of the motive sphere improve. At any severity the early beginning and regular carrying out medico-psychological assistance increases quality of life of patients. Prevention comes down to genetic inspection of couples in which families there is a child with this syndrome. The nature of chromosomal defect (sporadic or hereditary) allows to define risk of the birth of the second sick child.