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 arises due to the fact that only the copy of a certain gene received from the father functions correctly. The copy from the mother also shows some irregularities. Let's consider in more detail.
In the body of a healthy 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. Currently known diseases that are inherently similar to this disease.
A similar mechanism of occurrence can also be observed with Angelman syndrome, but even with this, 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 is a hereditary deterministic pathology that develops only with the development of some anomalies. In other words, with certain chromosomal abnormalities, the 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. In this case, the embedded information in DNA is not converted to RNA.
Scientists who have been identifying the causes of this hereditary pathology, previously believed that due to such a deviation, a homozygote is formed. Then they concluded that the predominant signs are present in autosomes, and the main route 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 15 chromosomes. 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 be explained only by such a phenomenon in genetic science as genomic imprinting, as well as uniparental dysomy.
With uniparental dysomy, both chromosomes are inherited from only one parent, but in order for this to happen, certain biochemical factors must influence the genetic material. This fact was established using prometaphase analyzes and DNA marking of some loci of this chromosome.
Prader-Willi syndrome is due to two main mechanisms: microdeletion of the 15th chromosome received from the father, and idiosomies of the maternal chromosomes, both of which are received from the mother.
In genomic imprinting, phenotype changes depend on in whose chromosomes - father or mother - expression has occurred.
Prader-Willi syndrome in children
The mechanisms of disorders occurring in the body of the patient with the syndrome are not yet fully understood. 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 lower lipolysis.
In addition, there are dysfunctions of the hypothalamus, which are mainly noted in its two nuclei - ventrolateral and ventromedial. Similar processes lead to malfunctions in the formation of secondary sexual characteristics. The reduced activity of tyronase in hair follicles and melanocytes leads to the fact that hair, skin and the iris of the eye are hypopigmented.
What are the main symptoms of Prader-Willi syndrome?
Symptoms of the disease
This pathology can be detected even in the initial stages of pregnancy with an incorrect location of the fetus and with its low mobility. In addition, a pregnant woman can significantly change the level of gonadotropin produced by chorionic cells, and there are symptoms of polyhydramnios. Based on these symptoms, a diagnosis cannot be made, however, they may be sufficient reason for further diagnosis.
Dysplasia
In children, Prader-Willi syndrome (pictured above) can be expressed in the presence of congenital dislocation of the thigh (dysplasia), in weakening of muscle tone, and also in impaired coordination. There are cases when a newborn could not independently suck and swallow breast milk. In this violation, nutrition is carried out using a probe. Respiratory disturbances may occur, and in some cases, artificial respiration is required.
Drowsiness
In addition, there are other symptoms of Prader-Willi disease. For example, children may experience increased drowsiness. As for external factors, the child has developmental delays. Therefore, such patients are characterized by low growth, underdeveloped hands and feet, strabismus often develops.
Other symptoms
In the future, this pathology is characterized by the following symptoms:
- Spinal curvature.
- Decay of deciduous teeth and increased saliva density.
- The tendency to overeat.
- Hypofunction of the gonads, which subsequently lead to infertility.
- Obesity.
- Delay in motor skills and speech development.
- Backwardness in psychomotor development.
- Lateness in puberty.
These symptoms are determined visually. In adolescence, the following symptoms are detected:
- Delay in speech skills.
- Overweight with very low stature.
- Unnatural body flexibility.
- Decreased intelligence and learning disabilities.
Diagnosis of Prader-Willi syndrome
This hereditary pathology can be noticed even during intrauterine 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 the birth, an experienced specialist is entitled to diagnose Prader-Willi disease already at the initial examination of the baby. However, special genetic testing is needed to confirm it. The content of chorionic gonadotropin is also investigated 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?
The diagnosis can be made according to the following clinical criteria:
- At birth, low weight and height of the baby in cases of full-term pregnancy.
- Incorrect position, including gluteal presentation of the fetus.
- Other microanomalies in development.
- Severe hypotension of the muscular system.
- Reduced pigmentation of the skin and hair.
- Obesity, developing, as a rule, by six months.
- Delays in psychological, motor and speech development.
Children who have this syndrome constantly require food and move very little. Due to excessive weight gain, they may experience a complication such as apnea, which is often the cause of death in a dream.
What is the treatment for Prader-Willi syndrome?
Treatment
To date, 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 for problems with swallowing, a stomach tube is placed through which enteral nutrition is performed. In cases of decreased muscle tone, massage and a variety of physiotherapeutic methods are indicated.
Recombinant growth hormone is administered daily to children with Prader-Willi disease, which supports muscle mass gain and helps reduce the patient’s appetite. Chorionic gonadotropin is also being replaced.
During this disease, hypogonadism is observed, that is, insufficient development of the genital glands and a change in the functions of the reproductive system. In this case, hormone replacement therapy is performed, which allows to stimulate growth and puberty.
In some cases, children with speech delays and poor psychological development may need the help of a psychiatrist or psychologist. And most importantly, you must constantly monitor the amount of food they consume. Children with Prader-Willi syndrome are prescribed special diet therapy.
The risk that the second child of a couple, whose first suffers from this disease, will be 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.
Improving overall well-being with a disease
Among people who have the syndrome, the indicators of somatic morbidity are significantly increased, communication is difficult, 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 health. If the condition is satisfactory and the patient feels well, his quality of life improves.
The following factors must be addressed:
- Increased risk of sudden death.
- Likelihood of illness.
- An increase in the number of factors that determine material well-being.
- Inadequate access to wellness and medical services.
People with Prader-Willi pathology have special needs due to their underlying illness. They need special treatment for acute and chronic pathologies, help in strengthening general health, etc. Their needs must be met in special institutions providing medical care, which, in turn, may consist in treating the underlying disease and somatic disorders, associated with the underlying 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 Prader-Willi syndrome. Now you know what this pathology is.