Prader-Willi syndrome is considered a very rare genetic disorder in which seven genes located on the 15th paternal chromosome are completely or partially absent and do not function normally.
This genetic pathology occurs due to the fact that only the copy of a certain gene received from the father functions correctly. There are also some irregularities in the copy from the mother. Let's take a closer look.
In the body of a he althy person there are copies of genes, thanks to which the organs can function without any deviations from the norm. With the development of Prader-Willi syndrome, such copies are absent. There are currently known diseases that are essentially similar to this disease.
A similar mechanism of occurrence can also be observed in Angelman syndrome, but even in this case, mutations affect the genetic material received from the mother. Such diseases, as a rule, manifest themselves in various forms and have varying degrees of severity. But, nevertheless, they are incurable.
Causes of the syndrome
Prader-Willi Syndrome -hereditary deterministic pathology, which develops only with the development of certain anomalies. In other words, with certain chromosomal disorders, parental genes begin to suffer, which leads to serious changes. The clinical picture develops when seven genes in the 15th paternal are absent or not expressed. At the same time, the embedded information in DNA is not converted into RNA.
Scientists, who were engaged in finding out the causes of this hereditary pathology, previously believed that due to such a deviation, a homozygote is formed. Then it was concluded that the predominant traits are present in autosomes, and the main way of transmission of the disease is inheritance.
Genetics performed numerous cytogenetic analyzes of the pathology, with the help of which it was found that the fathers of children affected by the disease had a translocation of chromosome 15. Photos of children with Prader-Willi syndrome are presented in our article.
Genetic mechanism
To date, it has been precisely established that with this pathology, the 15th chromosome is damaged in segments from q11.2 to q13. The same thing happens with Angelman syndrome. However, this disease is characterized by completely different symptoms. Such a dissonance can only be explained by such a phenomenon in genetic science as genomic imprinting, as well as uniparental disomy.
In uniparental disomy, both chromosomes are inherited from only one parent, but for this to happen, the gene material must be influencedcertain biochemical factors. This fact was established using prometaphase analyzes and DNA marking of some loci of this chromosome.
Prader-Willi Syndrome is caused by two main mechanisms: a microdeletion of the 15th chromosome, received from the father, and idiosomy of the maternal chromosomes, both of which are received from the mother.
With genomic imprinting, phenotype changes depend on whether the expression occurred on the chromosomes of the father or the mother.
Prader-Willi syndrome in children
Mechanisms of disorders occurring in the body of a patient with a syndrome have not yet been fully studied. However, at the same time they have a number of symptoms inherent only to this type of disease. It is believed that patients gain weight due to increased formation of fat cells and decreased levels of lipolysis.
In addition, there are dysfunctions of the hypothalamus, which are mainly noted in its two nuclei - ventrolateral and ventromedial. Such processes lead to failures in the formation of secondary sexual characteristics. Decreased tyronase activity in hair follicles and melanocytes results in hypopigmentation of the hair, skin, and iris.
What are the main symptoms of Prader-Willi syndrome?
Symptoms of disease
This pathology can be detected even in the early stages of pregnancy with an incorrect location of the fetus and with its low mobility. In addition, the level of gonadotropin produced by chorion cells can change significantly in a pregnant woman, and symptoms of polyhydramnios may be present. Based on these symptoms, a diagnosis cannot be made, however, they may be sufficient grounds for further diagnosis.
Dysplasia
In children, Prader-Willi syndrome (pictured above) can be expressed in the presence of congenital dislocations of the hip (dysplasia), in the weakening of muscle tone, as well as in coordination disorders. There are cases when a newborn could not suck and swallow breast milk on his own. In this violation, nutrition is carried out using a probe. Respiratory problems may occur and in some cases mechanical ventilation is required.
Drowsy
Besides this, there are other symptoms of Prader-Willi disease. For example, children may experience increased sleepiness. As for external factors, the child has developmental delays. Therefore, such patients are characterized by short stature, underdeveloped hands and feet, and strabismus often develops.
Other symptoms
In the future, this pathology is characterized by the following symptoms:
- Curvature of the spinal column.
- Caries of milk teeth and increased saliva density.
- Tendency to overeat.
- Hypofunction of the gonads, which further lead to infertility.
- Obesity.
- Delayed motor and speech development.
- Retarded psychomotor development.
- Delayed puberty.
These symptoms are determined visually. During adolescence, the following symptoms are identified:
- Speech delay.
- Overweight and very short.
- Unnatural flexibility of the body.
- Intelligence decline and learning disability.
Diagnosis of Prader-Willi Syndrome
This hereditary pathology can be seen even during fetal development during ultrasound. In such cases, women are recommended certain types of prenatal diagnosis, and if necessary, specialists use invasive methods to solve the problem.
After childbirth, an experienced specialist has the right to make a diagnosis of Prader-Willi disease already at the initial examination of the baby. However, specific genetic testing is needed to confirm it. The content of chorionic gonadotropin is also examined in the mother's blood. Thanks to such methods, it is possible to identify submicroscopic and functional pathologies at the DNA level.
What are the criteria for diagnosis?
Diagnosis can be made according to the following clinical criteria:
- At birth, low birth weight and height of the child in cases of full-term pregnancy.
- Incorrect position, including breech presentation.
- Other developmental microanomalies.
- Severe hypotension of the muscular system.
- Reduced skin and hair pigmentation.
- Obesity, usually developing by six months.
- Delays in psychological, motor and speech development.
Children with observedthis syndrome, constantly require food and move very little. Due to excessive weight gain, they may experience a complication such as sleep apnea, which is often the cause of death in their sleep.
What is the treatment for Prader-Willi syndrome?
Treatment
Until now, there are no specific treatments for the syndrome. Therapy is usually symptomatic. If a newborn has problems with respiratory activity, then he is transferred to artificial lung ventilation, and if there are problems with swallowing, a gastric tube is placed through which enteral nutrition is carried out. In cases of decreased muscle tone, massage and a variety of physiotherapy methods are indicated.
Children with Prader-Willi disease are given daily recombinant growth hormone to support muscle mass gain and help reduce the patient's appetite. The replacement of human chorionic gonadotropin is also carried out.
During such a disease, hypogonadism is observed, that is, underdevelopment of the gonads and a change in the functions of the reproductive system. In this case, hormone replacement therapy is performed to stimulate growth and puberty.
In some cases, children with speech delays and mental retardation may need the help of a psychiatrist or psychologist. And most importantly, it is necessary to constantly monitor the amount of food that they consume. Children with Prader-Willi syndrome are given special dietary therapy.
The risk that a couple's second childof which the first suffers from this disease, is born with the same genetic problems, is incredibly high. In such a case, parents are advised to undergo a consultation, where specialists will comprehensively examine them and calculate the risks.
Children with Prader-Willi disease need constant monitoring by an endocrinologist and a neurologist.
Improvement of general well-being against the background of the disease
Among people who have the syndrome, somatic morbidity rates are significantly increased, communication is difficult, and there is a need for specific assistance due to the characteristics of their disease. They may not understand why it is necessary to take care of their he alth. If the condition is satisfactory and the patient feels well, his quality of life improves.
The following factors need to be addressed:
- Increased risk of sudden death.
- Probability of getting sick.
- Increase in the number of factors that determine material well-being.
- Insufficient access to wellness and he alth services.
People with Prader-Willi pathology have special needs due to their underlying condition. They need special treatment for acute and chronic pathologies, assistance in strengthening general he alth, etc. Their needs must be met in special institutions providing medical care, which, in turn, may consist in the treatment of the underlying disease and somatic disorders, associated withunderlying pathology.
What is the life expectancy with Prader-Willi Syndrome? This disease often leads to a decrease in the life expectancy of patients up to 60 years. However, the prognosis for the recovery of such people is very disappointing.
The article provided a detailed description of the Prader-Willi syndrome. Now you know what this pathology is.
