During pregnancy, future mothers do prenatal screening to identify early genetic abnormalities of the fetus. One of the most serious diseases of this group is the syndrome described by John Edwards in 1960. In medicine, it is known as trisomy.
Edwards Syndrome - what is it in simple words?
In a healthy male and female reproductive cell there is a standard or haploid set of chromosomes in an amount of 23 pieces. After the merger they form an individual kit - karyotype. He as a kind of DNA-passport, contains unique genetic data about the child. A normal or diploid karyotype contains 46 chromosomes, 2 of each type, from the mother and father.
With the disease in question, in 18 pairs there is an extra duplicated element. This is trisomy or Edwards syndrome - karyotype, consisting of 47 chromosomes instead of 46 pieces. Sometimes a third copy of the 18 chromosome is present partially or does not occur in all cells. Such cases are rarely diagnosed (about 5%), these nuances do not affect the course of the pathology.
Edwards Syndrome - the causes of
Geneticists have not yet figured out why some children develop the described chromosomal mutation. It is believed that it is accidental, and no preventive measures to prevent it have been developed. Some experts link external factors and Edwards syndrome - the causes, supposedly contributing to the development of anomalies:
- prolonged use of drugs, alcohol, tobacco;
- heredity;
- age of mother or father over 45;
- infection of the genitals;
- long-term use of medications that affect the immune, endocrine and reproductive systems;
- exposure to radioactive radiation.
Edwards Syndrome - Genetics
Based on the results of recent studies in the 18 chromosome contains 557 DNA sections. They encode more than 289 kinds of proteins in the body. In a percentage of this is 2.5-2.6% of the genetic material, so the third 18 chromosomes are so strongly affected by fetal development - Edwards syndrome damages the bones of the skull, cardiovascular and genito-urinary systems. The mutation affects some parts of the brain and peripheral nerve plexuses. For a patient with Edwards syndrome, a karyotype is represented, as shown in the figure. He clearly shows that all sets are paired, except for 18 sets.
The frequency of Edwards syndrome
This pathology is rare, especially when compared with the more well-known genetic abnormalities. Disease Edwards syndrome is diagnosed in one newborn of 7,000 healthy infants, mostly in girls. It can not be asserted that the age of the father or matter significantly affects the probability of occurrence of trisomy 18. Edwards syndrome occurs in children only 0.7% more often if the parents are over 45 years old. This chromosomal mutation is also found among toddlers conceived at a young age.
Edwards Syndrome - signs
The disease under consideration has a specific clinical picture allowing to accurately determine trisomy 18. There are two groups of signs accompanying Edwards syndrome - the symptoms are conventionally classified into internal organ failure and external deviations. The first type of manifestation includes:
- umbilical, inguinal hernia;
- congenital heart defects ;
- absence of sucking and swallowing reflex;
- diverticulum of Meckel ;
- gastroesophageal reflux;
- atresia of the anus or esophagus;
- hypertrophy of the clitoris;
- underdevelopment of the corpus callosum, cerebellum;
- cryptorchidism ;
- improper position of the intestine;
- hypospadias;
- doubling of ureters;
- atrophy or smoothing of cerebral convolutions;
- segmented or horseshoe-shaped kidney;
- unformed ovaries;
- twisted spine;
- muscular dystrophy;
- low body weight (about 2 kg at birth).
Externally, too, it is easy to identify Edwards syndrome - a photo of babies with trisomy 18 shows the presence of the following symptoms:
- disproportionate small head;
- distorted face shape;
- narrow and short glottis;
- deformed, low-lying ears (stretched horizontally);
- absence of lobes, sometimes - tragus and even ear canal;
- short and broad chest;
- underdeveloped lower jaw;
- small mouth, often has a triangular opening due to a pathologically shortened upper lip;
- Embedded enlarged bridge of nose;
- "Rocking-stop";
- membranes between the fingers or their fusion (flap-like limbs);
- high palate, sometimes with a cleft;
- Short neck with prominent collar fold;
- transverse furrows and scallops on the palms;
- hemangiomas and papillomas on the skin;
- ptosis of the eyelids;
- strabismus;
- protruding occiput and low forehead.
Edwards Syndrome - Diagnosis
The described genetic disease is a direct indication for abortion. Children with Edwards syndrome will never be able to live fully, and their health will rapidly deteriorate. For this reason, it is important to diagnose trisomy 18 at the earliest possible date. To determine this pathology, several informative screenings have been developed.
Analysis for Edwards Syndrome
There are non-invasive and invasive techniques for studying biological material. The second type of tests is considered the most reliable and reliable, it helps to identify Edwards syndrome in the fetus at early stages of development. Non-invasive is the standard prenatal screening of the mother's blood. Invasive diagnostic methods include:
- Chorionic villus biopsy. The study is conducted from 8 weeks. To perform the analysis, a piece of the placenta shell is plucked, because its structure almost perfectly coincides with the fetal tissue.
- Amniocentesis . During the testing, a sample of amniotic fluid is taken. This procedure determines the Edwards syndrome from the 14th week of gestation.
- Cordocentesis. The analysis requires a little umbilical cord blood of the fetus, so this method of diagnosis is used only on late dates, from 20 weeks.
Risk of Edwards Syndrome in Biochemistry
Prenatal screening is carried out in the first trimester of pregnancy. The future mother must donate blood during the 11th to 13th week of gestation for biochemical analysis. Based on the results of determining the level of chorionic gonadotropin and plasma protein A, the risk of Edwards syndrome in a fetus is calculated. If it is high, the woman is brought into the appropriate group for the next stage of the research (invasive).
Edwards syndrome - signs by ultrasound
This type of diagnosis is rarely used, mainly in cases when the pregnant woman has not undergone preliminary genetic screening. Edward's syndrome on ultrasound can be identified only in later terms, when the fetus is almost completely formed. Characteristic symptoms of trisomy 18:
- intrauterine malformations of the cardiovascular and genitourinary system;
- anomalies of musculoskeletal structures;
- pathology of the bones of the skull and soft tissues of the head.
- Indirect signs of the disease on ultrasound:
- bradycardia;
- delay in fetal development;
- one artery in the umbilical cord (there should be two);
- a hernia in the abdominal cavity;
- visual absence of the bones of the nose.
Edwards Syndrome - treatment
The therapy of the mutation examined is aimed at alleviating its symptoms and facilitating the life of the infant. Cure Edward's syndrome and ensure the child's full development can not. Standard medical activities help:
- restore the passage of food with atresia of the anus or intestine;
- to organize feeding through the probe against the background of the absence of sucking and swallowing reflexes;
- stabilize the functioning of the cardiovascular system;
- normalize the outflow of urine.
Often Edwards' syndrome of newborns additionally requires the use of anti-inflammatory, antibacterial, hormonal and other potent drugs. It is necessary for timely intensive therapy of all associated diseases, which it provokes:
- Wilms tumor ;
- conjunctivitis;
- pneumonia;
- otitis media;
- pulmonary hypertension;
- sinusitis;
- urino-genital infections;
- frontitis;
- high blood pressure and others.
Edwards Syndrome - prognosis
Most embryos with the described genetic anomaly die during the gestation due to rejection by the body of an inferior fetus. After birth, the forecast is also disappointing. If Edwards syndrome is diagnosed, how many such children live, we will consider in percentages:
- 60% - not more than 3 months;
- 7-10% - 1 year;
- about 1% - up to 10 years.
In exceptional cases (partial or mosaic trisomy 18), units can attain maturity. Even in such situations, John Edwards syndrome will inexorably progress. Adult children with this pathology remain oligophrenic forever. The maximum that they can be taught:
- raise your head;
- smile;
- independently there;
- to recognize a limited circle of people.