Down syndrome

Description:

In 1866 the English doctor Down allocated group of mentally retarded patients and peculiar somatic anomalies, having called a disease of "a Mongoloid idiocy". However in 1846 patients with the same clinical signs were described, the disease was called "a scaly idiocy" because of a xeroderma. The cause of illness was established in 100 years after allocation of an independent nosological form by Down when the group of scientists found in these patients an excess chromosome from group G – a chromosome 21.

Etiologies of Down:

Among the chromosomal pathologies revealed at the person. The trisomy 21 is the most widespread. Among newborns the Down syndrome comes to light with a frequency of 1:650, in population 1:4000. The ratio of boys and girls makes 1:1. About 10% of patients with an oligophrenia have a Down syndrome.
Distinguish three cytogenetic options of a Down syndrome: a trisomy of 21 chromosomes, translocational option (21 chromosomes on 13 and 22) and mosaic option. The trisomy of 21 chromosomes meets in 94%, translocational option – in 4% and mosaic option – in 2%.

Down syndrome symptoms:

Most often children with a Down syndrome are born from the complicated pregnancy proceeding with a gestosis, threat of an abortion, etc. Mothers of patients have a dissonant obstetric anamnesis (abortions, still births). The average duration of pregnancy is slightly less than normal. Patients are born more often with the reduced mass and length of a body; the head circle in half of cases does not reach 32 cm.
In development of speech and static functions the delay is noted: they begin to hold the head on average from 4-5 months, to sit from 8-9 months, to go – by 2 years, pronounce the first words in 1,5-2 years, the phrase speech begins from 4-5 years.
Diagnosis of a Down syndrome in most cases does not cause difficulties in the newborn. These patients are so similar at each other that speak not about diagnosis, and about "recognition" of this chromosomal anomaly. More often at this syndrome there is a brakhitsefalny skull of which it is characteristic a smoothed nape. The face of the sick child is flattened, the slanting section of eyes (the internal corner of eyes is lower than outside), an epikant, Brushfild's spots (light spots on an iris), a hypertelorism, the expanded and flattened bridge of the nose, small underdeveloped auricles are located low, the upper jaw is underdeveloped. The increased "folded" language quite often acts from a mouth. The high sky, growth of teeth, a diastem, cross striation on lips is broken. The short neck, wide brushes with short fingers is characteristic of patients with a Down syndrome. Little fingers are bent,  the clinodactyly, expanded intervals between 1 and 2 fingers of feet is observed. Also other anomalies meet: deformations of a breast, syndactylia, shortening of tubular bones, basin hypoplasia. In connection with specific a structure of the voice device a voice at sick children a little hoarse. Patients of low growth, their bearing is broken, omission of shoulders is observed, the head and a trunk when walking are inclined forward. Skin is usually dry, on a face it is quite often shelled, cheeks with a characteristic flush. It is quite often possible to find an underdevelopment of external genitals, a divarication of recti, umbilical and inguinal hernias. Inborn defects of digestive tract or heart are quite often observed.
The symptomatology of a Down syndrome includes also dermatoglifichesky features as a cross furrow on one on one or both palms, one flexion furrow on the 5th finger, the distal arrangement of an axial triradius, frequency of ulnarny loops is higher, and curls on fingers – below, than in other population.
At a research of the neurologic status insufficient motility, a hypomyotonia, dysfunction of a vestibular mechanism is noted.
At a full trisomy 21 mental retardations are found practically in all patients, and generally it is an oligophrenia in degree of a deficiency of intellect (65-90%). Moronity and an idiocy in an identical ratio is diagnosed for the others.
Intelligence underdevelopment total. Thinking of patients tugopodvizhno, emotions are superficial, malodifferentsirovana. Children are, as a rule, tender, affectionate, good-natured,  well acquire simple everyday concepts and skills.
At a Down syndrome intellectual defect goes deep patients with age.
At mosaic option of a syndrome of Dan considerably easy mental retardation meets more often, also the normal intelligence is described.
Many patients with a trisomy 21 are capable to conduct independent life, seize simple professions, establish families.

Diagnosis:

For an exception of translocations it is necessary to carry out karyotyping, i.e. a research of chromosomes. Among children with a Down syndrome is slightly higher, than in population, the leukosis therefore hematologic researches annually are required comes to light, determination of level of thyroid hormones (hypo - a hyperthyroidism), at children with a leukocyturia and fever of not clear genesis is shown – for detection of anomalies of uric ways, all children have an ultrasonography of an abdominal cavity an echocardiography (defect of an interventricular partition it can not be shown at the birth).

Prenatal diagnosis:
1. Ultrasonography: gipotelorizm, brachycephaly, excess cervical fold (16-29 week of a gestation), increase in the front-back size of collar space (10-14 weeks of a gestation), lack of a bone of a nose (12-14 weeks of a gestation), inborn heart disease, moderate ventrikulomegaliya, duodenum atresia, hyper echoic intestines, not immune edema of a fruit, shortening of extremities, hypoplasia of an average phalanx of a little finger, moderate hydronephrosis.
2. Biochemical indicators of blood serum of mother:
- decrease in level of serumal AFP less than 50%
- increase in level of not conjugated estriol and HGCh.

Current and forecast:

Patients with a Down syndrome are more often. than other people, have some diseases in this connection complications from other systems meet more often. Existence of fistulas and other anomalies of development of bodies of a GIT causes obstruction of intestines.  Hypo - and the hyperthyroidism is observed at 5-8% of patients. The leukosis occurs at 0,5% of children with a Down syndrome. Alzheimer's disease at 1/3 patients is more senior than 35 years.
High mortality at a Down syndrome is caused first of all by expressiveness of heart diseases. The expected life expectancy is reduced: about 30% die on the 1st year of life, 50% do not live up to five-year age and only 8% overcome 40leny a threshold. At a third of patients in the 1st year of life normal development, and  in the subsequent – insignificant deviations is observed (delay of development after the 1st year of life, moderate deviations of speech and cognitive functions). Gastrointestinal complications and heart failure at inborn heart diseases can have the acute beginning.
The hypothyroidism is shown usually in 6 months after the birth, typical
symptom – a growth inhibition.

Treatment of the Down syndrome:

Sick appoint psychostimulants, neurometabolic drugs, fortifying therapy. Sydnocarbum on 10-15 mg a day, aminobosoms on 250-500 mg a day, Encephabolum on 100 - 150 mg a day, Pantogamum on 250-500 mg a day, piracetam on 400-800 mg a day is applied. Treatment duration each drug 2-3 months. Vitamin therapy (B1, B6, B12), treatment by hormonal drugs – Thyreoidinum on 0,05-0,2 mg a day, and Prephysonum on 1 ampoule a day, on a course of 30 injections is shown. Drug treatment needs to be combined with medical and pedagogical correction.
Surgical treatment at a Down syndrome is applied to correction of inborn heart diseases.

Prevention:

Prevention of a Down syndrome consists in early detection of a disease for what it is used:
- prenatal karyotyping at the woman from the woman from risk group;
- the low maintenance of APF in blood serum of mother on 14-16 week of pregnancy (helps to reveal 1/3 cases).
Medicogenetic consultation. Calculations of genetic risk significantly differ depending on a cytogenetic form of a disease.
At identification of a translocational form of a Down syndrome  the research of a karyotype of parents is necessary. Identification at any of parents of the balanced translocation does necessary at the subsequent pregnancies pre-natal diagnosis by amniocentesis since the risk of the birth of the child with a Down syndrome in these cases is increased. So, at the translocation on type 13/21 revealed at the father, the risk makes 2,5%, at revealed at mother makes up to 10%. If the translocation of type 21/21 is found in one of parents, then the risk makes 100%.
Practice of medicogenetic consultation shows that amniocentesis is reasonable when risk of the birth of the child not less than 10%, one of parents has any balanced translocations or a mozaytsizm if mother is more senior than 35 years.
The risk of the birth of the sick child at a trisomny form of a Down syndrome depends on age of mother - up to 35 years it is considered close to 1%, by 40 years – 15, and in 45 years and is more senior – about 3%.
It is considered that the mozaytsizm occurs at 10% of mothers having children with a Down syndrome. At a mozaytsizm of parents the genetic risk follows confidants to 30%, i.e. to risk of the birth of the child with a trisomy 21 at women with a Down syndrome.