Martin-bell syndrome: signs, symptoms, and treatment

Contemporary rapid development of medicine has allowed to open to humanity a lot of previously unknown diseases. Of particular importance in the twentieth century played the deciphering of the genetic code, allowing to identify the causes of many genetic and chromosomal abnormalities. Known for more than 3,000 diseases related to quantitative and qualitative changes in the genetic material. A relatively new pathology is a syndrome of Martin-bell, which has a fairly high percentage of childhood disability.

Disease, Martin-bell-syndrome or neurological disorder?

The Syndrome of Martin-bell — the inherent pathology associated with fragility of the X chromosome. The concept of “brittle” means a visual sharp contraction of the ends of the X chromosome. Such changes confirm the Martin-bell syndrome. Children's photos on the left indicates the backlog of psychomotor development, which has a tendency to progression from early childhood.

Causes

It is known that the human genotype normal is 46 chromosomes, two of which — sex X and U. in women, respectively, chromosome set will look like - 46 XX, while the male is 46, XY. These carriers of genetic information consists of several repetitions of the amino acids where incorporated information about the structure and functions of the future living organism.

The Disease, Martin-bell syndrome (fragile X chromosome) develops due to changes of the X chromosome, so it can hurt both women and men. Thinning of the site of the X chromosome due to abnormal increase of specific amino acid residues repetitions — cytosine-guanine-guanine (C-g-G). This combination of repetition is present several times in other genes, however, it is important, in fact, the number of these repetitions. In the norm, it ranges from 29 to 31. In the case of the syndrome of Martin-bell this number is dramatically increased and may meet from 230 to 4000 times, which leads to an increase in chromosomes and impaired functioning of a specific gene-FMR1, which is responsible for the proper functioning and development of the nervous system. Result becomes obvious after a short period of time after birth and is manifested by psychomotor retardation.

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Manifestations

The Number of repeats of cytosine-guanine-guanine leads to different variants of the clinical manifestations of the disease, Martin-bell. The syndrome may have hidden forms. If the study reveals from 55 to 200 repeats, there is premature — the border changes which make the person a carrier, but no apparent changes in the nervous system. In the Mature and senile age can develop atactic syndrome and primary ovarian failure in women. The probability of transmission of the syndrome is high. There are also the intermediate state is between 40 and 60 repeats of nucleotides that does not manifest clinically and inheritance can occur through several generations.

Inheritance

Genetics relate this disease to the group of pathologies, coupled with the floor, i.e. with the X-chromosome. In men the disease manifests itself more and more distinctly, as their genotype contains one X chromosome. In women, the pathology develops in the case of both "pathological" X-autosomes. Very rarely men premutational possible option and carrier. Women are significantly more often carriers of disease and transmit "pathological" chromosome with equal probability for both daughters and sons. Sick father can transmit his X chromosome only to their daughters. Inheritance of the syndrome gradually increases from generation to generation, which was called the Sherman paradox. The clinical course of the syndrome is much harder for men.

Symptoms

The fragile Bella, the symptoms of which resemble autism are not always able to recognize even the most experienced pediatrician or neurologist.

The Clinical picture may vary depending on the number of repeats C-G-G.

In the classic version of the psychomotor retardation indicates a potential syndrome Martin-bell. Photo baby lets you see the first characteristic symptoms of the disease. Observed confusion and discoordination movements, developing muscle weakness. Quite often children suffer from autism. On examination, the neurologist detects disruption of the oculomotor nerve and some abnormalities in the brain. With age, the situation escalates, gradually increasing picture of mental retardation.

There are Always mental impairment: the child often mumbles to himself, unmotivated shows faces, often flapping the hands, sometimes behaves very aggressively. Such symptomatology is somewhat reminiscent of schizophrenia. Another option is autism, which begins to develop in early childhood.

Syndrome Martin-bell: signs

A Specific feature in boys are increased size of the testicles (macroorchidism), but it can be detected only in puberty. However, any endocrine disorders do not exist.

Changes the appearance is relatively nonspecific, but may mislead the doctor for the right diagnosis. The child is often a bighead, face, and slightly curved beak-shaped nose. Marked the large size of the hands and feet, fingers have greatly increased the range of motion. Often the skin has a high elasticity.

Manifestation premutational variant of the disease have certain characteristic features. For atactic syndrome characterized by tremor and impaired memory, especially short-term, marked changes in mood and the gradual development of dementia with a decline in cognitive function (inability to read and understand speech). Symptoms develops most often in men-carriers and has more severe course compared to women.

For the primary failure of ovarian function characterized by the appearance of premature menopause and dysfunction of system "hypophysis-ovaries". Increased contents of follicle-stimulating hormone, which leads to the disappearance of menstruation and the appearance of vascular symptoms. The disease progresses gradually and requires hormone replacement therapy.

How to diagnose syndrome

Indicative of the disease in the early stages the child will fit the cytogenetic method. There is a collection of cellular material of the patient and W added vitamin (folic acid) as a provocateur of change in the chromosomes. After some time, the study reveals part of the chromosomes with significant thinning, which indicates disease, Martin-bell, fragile X-chromosome. This laboratory test method is not sufficiently accurate in the later stages, which is associated with the widespread use of multivitamins, which include folic acid.

Is a highly specific polymerase chain reaction (PCR), which allows to decipher the structure of the amino acid residues in the X-chromosome and indicate the syndrome of Martin-bell. Photo made with an electron microscope, shows a patch of thinning autosomes.

Separate, more specific option is the combination of PCR with detection on capillary electrophoresis. This examination with high precision detects abnormalities of chromosomes in patients with atactic syndrome and primary ovarian failure.

Treatment

After the PCR to the diagnosis of "syndrome of Martin-bell", treatment should begin as early as possible.

As the disease is congenital and is of chromosomal origin, therapy is reduced to the relief of major symptoms.

Therapeutic scheme aims to minimize the manifestations of psychomotor retardation, correction changes with atactic syndrome and hormonal support in primary ovarian insufficiency.

Children with mental retardation and confirmed the result of PCR diagnose "Martin-bell syndrome". Russia does not have medical institutions which conduct rehabilitation for these children, so treatment deals with the pediatrician and related professionals. It is worth noting that the treatment of children than adults. Apply techniques of cognitive-behavioral therapy sessions with a psychiatrist, individual therapy, mild forms of psychostimulants. A relatively new direction is the use of drugs based on folic acid, but long-term results are still being examined.

For adults, the therapeutic treatment includes stimulants and antidepressants, is held constant dynamic supervision by psychiatrist and psychologist. In private clinics, therapy microinjections of the drug "Cerebrolysin" and its derivatives, cytomedines (medication "Lidasa", "Solcoseryl").

Atactic syndrome use nootropics and drugs to thin the blood, angioprotectors and mixtures of amino acids. Primary ovarian failure in women is subject to adjustment estrogens and herbal remedies.

The Effectiveness of treatment is relatively low, but allows for some time to slow down the progression of the disease.

Prevention

The Only way of prevention is screening of pregnant women. In the developed
Countries introduced the survey to identify the syndrome of Martin-bell in the early stages and to terminate the pregnancy. The alternative is in vitro fertilization, which can contribute to future child inherits “healthy” X-chromosome.