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Down-Edwards syndrome is one of the most common chromosomal aberrations, i.e. disorders in the number or structure of chromosomes.
Numerical aberrations
Chromosome 21 trisomy (Down syndrome)
A trisomy is the presence of three, instead of two, normal copies of a chromosome. Trisomy 21 affects 1 in 650-700 newborns alive. This disorder is also found quite often in spontaneously aborted fetuses. The frequency of this defect is higher among the offspring of women giving birth after 35 years of age.
There is no single characteristic clinical symptom for the diagnosis of Down’s syndrome, but rather the coexistence of several or a dozen or so features. The nature of mental retardation is also nonspecific.
The baby has a distinctive face, with a flat nose, wrinkles in the corners of the eyes, a large tongue, small ears and a flat head. There is also muscle laxity. The most common concomitant malformations are heart defects, which are the most common cause of death in newborns and infants. In the next place are defects of the digestive and urinary tract. Other features include short stature – usually around 150 cm. There are also cataracts, epilepsy, and hypothyroidism. All children with Down’s syndrome show mental retardation, usually of a moderate degree, which is the most serious and constant symptom of the syndrome. The motor development of these children is quite good, as is their emotional development and social maturity. All males are infertile and females can become pregnant, with a 50% chance of passing trisomy 21 to their offspring. If the patient is at the first year of survival, the average survival time is 50-60 years, but adults are at increased risk of pre-senile Alzheimer’s dementia.
Trisomy 21 can be diagnosed in prenatal tests – laboratory tests (low levels of alpha-fetoprotein in the mother’s serum means an increased risk of Down’s syndrome in the fetus) and imaging tests (e.g. nuchal translucency tests on ultrasound).
Chromosome 18 trisomy (Edwards syndrome)
The clinical picture of this trisomy is not as characteristic as, for example, Down’s syndrome. These children are born from transferred pregnancies during which, in the studies, low fetal mobility, delay in its development or placental underdevelopment were observed. Nevertheless, most pregnancies with trisomy 18 become spontaneously aborted.
Edwards’ syndrome is more common in girls. The most characteristic feature is, in clenched fists, the overlapping of the index and fifth fingers over the other fingers. In addition, the image of the syndrome also includes: microcephaly, prominent bones of the occiput, additional fontanels, deformed, low-set ears, defects of the eyeballs, cleft lip and / or palate, a short, wide neck, valgus knees and others.
Only 10% of children with Edwards syndrome live in the first year of life and have severe developmental disabilities. In 95% of cases, congenital heart defects are diagnosed, which are the most common cause of death in a child.
Chromosome 13 trisomy (Patau’s syndrome)
This change in chromosome numbers usually leads to miscarriage, so it is much less frequently diagnosed in live newborns than trisoma 21, with an average of 1 in 5000-12000 according to various authors. More than half of children with this syndrome die in the first month of life, survival beyond three months is rare and is characterized by severe psychomotor development impairment. 90% of sick children die before the age of one.
The abnormalities in Patau’s syndrome, in addition to mental retardation, include, but are not limited to: microcephaly, cleft lip and / or palate, minuscule, distorted, low-set auricles, cystic kidney disease, extra fingers or underdeveloped mandible. Heart defects are almost the rule.
Children affected by such aberrations require the care of many specialists from the moment they are born. Parents also need help, among others psychologists or social workers or hospices. Children who do not die in the first months of life still need to be provided with proper care, sometimes with apparatus or equipment that enable them to function.
A lot of support and information is available from genetic counseling centers around the country. The websites and blogs of parents who struggle with such problems are a huge repository of knowledge and a support for other parents. They exchange experiences, information and words of encouragement with each other. It is very edifying to know how much effort they devote to their sick children and what great love they have for their children, despite all the adversities.
Extra X chromosome in a male (Klinefelter syndrome)
A human has 23 pairs of chromosomes, one of which is sex chromosomes. The correct record – karyotype, looks like this: 46 XY – for a man and 46 XX for a woman. 46 represents the total number of chromosomes and XX or XY define gender.
The karyotype of a man with Klinefelter syndrome is 47 XXY. This aberration occurs on an average of once in 800-1000 male newborns, according to various authors. Klinefelter’s syndrome is rarely diagnosed in childhood, as it usually does not show any characteristic features. There may only be mild developmental delay and some degree of immaturity. Older boys have small, soft testicles. Men are usually characterized by weak muscles and a delicate build, with long limbs and a short torso. Due to the fact that these features are not very disturbing, the diagnosis of Klinefelter syndrome is usually made during the diagnosis of infertility. The sexual activity of these men is reduced, there are cases of abnormal sexual behavior and difficulties in social adaptation. Most men show a normal level of intelligence.
X Chromosome Monosomy (Turner Syndrome)
Monosomy is the presence of only one chromosome from a given pair. If such aberration affects a chromosome other than the sex chromosome, it is lethal for the zygotes, not even in early spontaneous miscarriages. X chromosome monosomy is found in aborted fetuses, as well as in female newborns.
According to various authors, the incidence of Turner syndrome is 1 in 2500-5000 girls born. The karyotype of such a child is 45 X (instead of 46 XX). In infants with Turner syndrome, abnormalities are often difficult to identify at first glance, and the diagnosis may suggest excess skin on the nape of the neck and swelling of the hands and feet. Other features found in women with X momosomy include, but are not limited to short stature, short, wide (webbed) neck and wide chest, valgus of the elbows. The hairline on the forehead and nape is low, as are the auricles. Multiple pigmented lesions on the skin occur in 60% of cases, heart defects are found in 20%, and kidney defects are present in 40-60% of cases. The vast majority of women with Turner syndrome are sterile, they are also characterized by underdevelopment of the genital organs, lack of armpit hair, and sometimes also pubic hair, and these women do not menstruate. Due to the impaired or completely absent work of the ovaries, these women suffer from cardiovascular diseases and osteoporosis. These processes can be delayed by using hormone replacement therapy. Girls with Turner syndrome have normal mental development, but some of them may experience some delays and a spatial orientation disorder. Life expectancy is normal.
Structural aberrations – they arise as a result of breaking chromosomes and joining their fragments into new configurations.
Prader-Willi syndrome and Angelman syndrome
They concern the loss of a small fragment of chromosome 15. If the chromosome with the defect is passed on by the father, the child has Prader-Willi syndrome, if the mother – Angelman. The former occurs in 1 in 10-000 live births, the latter is slightly more common.
Symptoms of Prader-Willi are visible after birth, although their different picture than in older age makes it difficult to make a correct diagnosis. Initially, these are: reduction in muscle tension and feeding difficulties due to a lack of suckling reflex. Psychomotor development is delayed from the beginning. In 2-3 r. excessive appetite appears, leading to obesity in a relatively short time. The hands and feet are small. Other features include short stature, a small dimension between the temples (narrow face), almond-shaped eyelid fissures, corners of the mouth pointing downwards, and hair usually very light-colored. Behavioral disturbances and tantrums appear with age.
Angelman syndrome was called happy puppet syndrome.
The first symptoms of abnormal development usually appear around 6-9 months of age. The disease picture is dominated by significant mental retardation, balance disorders and epilepsy. The distinctive features of the appearance include, among others prominent mandible, protruding tongue, flat occiput, widely spaced teeth. Most children with Angelman syndrome have significant speech impairment. About 30% of children do not speak and the rest use only single words. For this reason, children should be allowed to use special aids as early as possible to develop other means of communication. Patients have bouts of laughter inadequate to the situation.
Williams syndrome
It is a syndrome that affects an estimated 1 in 20 children and has a wide range of symptoms, with varying severity. The first symptoms in the neonatal and infant period are feeding difficulties, poor weight gain, reduced muscle tone, and developmental delay, which may vary in severity in later years. In old age, a rough voice, learning difficulties are characteristic. These patients have a specific appearance known as an elf face – characteristic auricles, a wide forehead, thick lips, a long nasal ridge, the irises are usually blue or green. There are also concomitant defects of the cardiovascular system, kidney defects and inguinal hernias. Patients with Williams syndrome are characterized by a specific personality – ease of establishing contacts and a friendly, positive attitude towards the environment as well as a love of music. Some of these people have absolute hearing.
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