Course Paper: Prader-Willi Syndrome

Introduction

Recent revolutionary breakthroughs in behavioral genetics, molecular biology, cognitive science, developmental neurobiology, and developmental psychology have considerably changed research methodologies and conceptual frameworks. This has led to a new understanding of the neuropathological underpinnings and genetic causes of behavioral and cognitive deficits across numerous neurodevelopmental disorders. These changes impact individuals with Prader-Willi syndrome as well as others such as Down syndrome, autism, and dyslexia. A new paradigm has witnessed the role of genetic factors that are linked also with environmental variables. Prader-Willi syndrome occurs in individuals because of chromosomal anomalies, and it may have serious complications throughout the entire lifespan. Many studies assume that Prader-Willy syndrome is a result of mixed genetic and epigenetic effects that happen because of the deficiency of gene expression from the paternal chromosome at the locus q11-q13 on chromosome 15.

In this view, extreme floppiness at birth determines physical, behavioral, and cognitive abnormalities that continue developing during childhood and adolescence and lead to more complex social and health problems in the future. As a rule, it is rather challenging to detect the precise nature of genotype and establish the biological, physical and behavioral features. The imprinted genes play a predominant role in the development of individuals with PWS, and it generates the necessity for further scientific research related to their etiology and the processes involved. Their presence encourages a researcher to identify mechanisms responsible for this abnormality. Prader-Willi syndrome is a genetically determined condition, and it is rather hard to identify precise treatments and prevent this disorder. However, individuals with Prader-Willi syndrome require early diagnoses and proper treatments in order to manage their disorder and feel quite adequate in the social environment. Moreover, some complications such as obesity should be of a special concern of the therapists and other professionals.

History

People with Prader-Willi syndrome have been born for many centuries, but there was no scientific evidence for this abnormality. PWS appeared in the medical practice after the description of its epidemiology and symptoms in 1956 (Pinel, 2014). The phenomenon of this impairment was described earlier by endocrinologists Prader, Willi, and Labhart. They indicated the unusual extended features associated with a diminished fetal activity, feeding problems in infancy, underdeveloped sex organs, weak muscle tone, small feet and hands, cognitive impairment, etc. Their second report was published the same year where the authors explicate a new research. In 1963, Prader and Willi published another report that included original nine cases and a new research that added mental retardation and diabetes mellitus to the clinical picture (Pinel, 2014). Meanwhile, more and more people were identified with similar features, and it encouraged scientists to conduct more researches to gather common characteristics. First observations showed such abnormalities as hypotonia, feeding problems, male hypogenitalism, delayed developmental milestones, and obesity.

The following years, the study of Prader-Willi syndrome was developed by Zellweger and Schneider (1968), Gabilan and Royer (1968), and Dunn (1968) (Caldwell & ‎Taylor, 2013). These studies indicated that PWS consisted of two distinct phases followed by dental, orthopedic, and developmental characteristics. In 1972, Hall and Smith gave a detailed research based on thirty-two patients that proved the previous investigation but also discussed personality and behavioral problems that could appear later in life (Cassidy, Schwarts, Miller & Driscol, 2012). Many other scientists provided the evidence that abnormalities increased with age and could become the cause of many clinical problems. Numerous findings of this period indicated that PWS was a sporadic event in families because this abnormality occurred in one family and affected brothers, sisters, etc. (Grechi, Cammarata, Mariani, Di Candia & Chiumello (2012). One of the most interesting features of PWS was the establishment of abnormalities in eating behavior (hyperphagia). However, scientists did not recognize the genetic cause of PWS until 1981 when the considerable changes occurred in the science (Lukoshe, White, Schmidt, Van der Lugt & Hokken-Koelega, 2013).

Epigenetic Causes of PWS

According to Caldwell & ‎Taylor (2013), Prader-Willi syndrome is a result of mixed genetic and epigenetic effects that occur because of the deficiency of gene expression from the paternal chromosome at the locus q11-q13 on chromosome 15 (p. 23). Normally, these genes are expressed when inherited from the father, but the absence of their functions leads to abnormalities starting from the developing of a fetus through the whole lifespan. Therefore, extreme floppiness at birth determines behavioral, physical, and cognitive abnormalities that continue developing during childhood and adolescence and lead to more complex social and health problems in the future. The research asserts that PWS is accompanied by the three following features:

• The presence of intellectual disability that is characterized by functional impairments
• Psychiatric illnesses and particular abnormal behaviors have a negative impact on the quality of life of a person and his or her family
• PWS is accompanied by a habit to overeat that can cause obesity

In order to understand the phenomenon, both theoretical and practical researches are needed. With respect to the practice, it is important to gain knowledge that can help doctors improve the life of the affected persons and solve various related problems such as obesity. Pinel (2014) notes that it is rather challenging to identify the precise nature of genotype and establish the biological, physical and behavioral features. Furthermore, from the practical perspective, it is necessary to determine complex therapeutic, social, psychological, nutritional, and educational needs of these patients. With respect to genetic impacts on human behavior, there are specific features of PWS that prove its scientific significance. First of all, as the imprinted genes play a predominant role in the development of individuals with PWS, it generates the necessity for further scientific research related to their etiology and the processes involved. Furthermore, the role of imprinted genes encourages a researcher to identify mechanisms that are responsible for this abnormality.

Many findings assume that Prader-Willi syndrome is a genetically determined condition (Caldwell & ‎ Taylor, 2013). With respect to behavior, there are actually two types: hyperphagic individuals with psychiatric and behavioral impairments and hypotonic persons. All patients with PWS demonstrate behavioral, physical, and psychological manifestations resulting from the deficiency of gene expression from the paternal chromosome at the locus q11-q13 on chromosome 15 (Caldwell & ‎ Taylor, 2013). The nature of inadequate behaviors is influenced by the environmental factors and may be improved by successful interventions. Many scientists believe that environmental interventions will bring significant change in the future, reducing some significant behavioral and physical abnormalities.

Studies of rare cases indicate that the majority of patients with Prader-Willi syndrome suffer from cholesterol metabolism (Pinel, 2014). Although, a great number of patients have point mutations, it has been proved that the large genomic deletion is one of the causes for PWS. This discovery allowed recognizing the enigmatic UPD (uniparental disomy) as an epigenetic cause of PWS as well as Autism syndrome. Admittedly, the disorder cannot be determined by blood-derived DNA if the symptoms are epigenetic rather than genetic. Mutations and epimutations in the imprinted genes give rise to epigenetic and genetic phenotypes (e.g. inheritance of two copies of chromosomes from one of the parents and none from the other).

Symptoms and Treatments

Symptoms of Prader-Willi syndrome are characterized by extraordinary overeating (hyperphagia) and possessed food-seeking behaviors. Cassidy et al. (2012) believes that hyperphagia has a place due to the dysfunction of the hypothalamus that prevents them from the normal feeling of fullness. This behavior leads to overeating, obesity, and reduced metabolic rates that accompany PWS patients throughout their lives. For example, in spite of persistent supervision, they can steal food, eat unpalatable items, or forage through the garbage. PWS life-threatening condition such as the complication of obesity often leads to mortality and morbidity because of overeating. However, obesity is not the only feature that is of the greatest concern. There are numerous other symptoms, both behavioral and physical, that should be taken into consideration while researching symptoms of this abnormality.

Many studies suggest that PWS babies have a poor sucking reflex that requires various techniques to feed them (Lukoshe et al., 2013). Other physical features appear during their development and demonstrate short stature, characteristic facial features, sleep disturbance, decreasing vomiting, thick and viscose salvia, and temperature problems. Interestingly, people with Prader-Willi syndrome show a relatively higher range of intelligence compared to individuals with other mental disorders such as Down syndrome or X syndrome. For example, the average IQ of PWS children often reaches 70 percent (Caldwell & Taylor, 2013). However, the majority of them rarely behave in accordance with their IQ because of their eating abnormalities. Regarding cognitive abilities, many children show significant success in reading while a rather low one in arithmetic. Thus, cognition is characterized by the uneven academic performance that demonstrates an insignificant discrepancy in reading versus arithmetic.

Young children with PWS usually do not possess negative behavior, and parents and doctors consider them as placid, pleasant, and friendly. However, older children and adults show more signs of maladaptive behavior, including stealing, lying, stubbornness, rigidity, and oppositionality. Many of them can be rather manipulative and clever, especially in their attempts to steal food. Many studies suggest that maladaptive behaviors increase over the course of development and lead to aggression, isolation, pessimism, negative self-esteem and image (Cassidy et al., 2012). In contrast, opponents consider that emotional and behavioral peculiarities lessen with age, and clients with Prader-Willi syndrome may be more sensitive to interventions (Grechi et al., (2012). However, some behaviors may deteriorate with age, while others may stay stable or improve. Although such patients are addicted to stealing food, they rarely demonstrate psychiatric disorders such as dementia, tic disorders, autism, or schizophrenia. Only some of them may have psychotic episodes in the form of hallucinations.

Besides low-frequency problems described above, PWS patients appear to experience obsessive-compulsive disorder and affective disorders. Cassidy et al. (2012) assume that maladaptive behavior induced by Prader-Willi syndrome is represented through low self-esteem, sadness, worries, and fears. Compulsive-type symptoms have been PWS symptoms for a long time and include constant food-seeking habits, skin picking, hoarding pencils, pens, paper, trash, etc. Admittedly, there are vast individual differences within persons, and more research is needed to identify them. However, it is known that these differences are determined by genetic status and psychological variables such as family support or self-esteem. A vast amount of symptoms may also depend on adaptive skills, personality strengths, and social competencies and a degree to which they can shift during the lifespan.

Children having Prader-Willi syndrome should be treated as early as possible for better results. Most children require special approach to medical interventions due to their strengths and weaknesses that determine their behavior disorder. Usually, they are placed in special classrooms or regular classrooms with special assistance. Supervision is a necessary tool for controlling food during lunches, which may prevent PWS individuals from overeating at school. Furthermore, students who face challenges in the everyday environment require numerous professionals who can help them manage their problems. Therefore, physical, speech, and occupational therapists should be also in service. The school nurse, social workers, and school psychologists are usually a part of the educational team in schools with PWS children. Individuals with PWS experience speech, language, and motor delays from the early childhood that continue throughout their lifespan. As a rule, PWS infants have a poor muscle tone (hypotonia) that makes muscles floppy and weak. Moreover, the majority of babies require special feeding and have a weak cry. These concerns lead to speech and motor delays and need physical and occupational therapies to increase their developmental growth.

Pinel (2014) noted that children with PWS had difficulties in establishing relationships with their peers because of their speech and language delays. Therefore, it is important to provide formal social skills training for young and older children to help them better adapt in the classroom environment. They may also benefit from trainings that will encourage them for nonverbal communication. Children with PWS possess gross motor skills, low tone, poor motor planning, and decreased strength, and they are used to struggling with cutting, writing, and other motor tasks. In the early childhood, many of them have poor balance and coordination. As a rule, schools that implement physical and occupational therapy help children with Prader-Willi syndrome improve their development and physical abilities to take part in classroom activities. Children and adults with PWS often require individual or group psychological treatment with other disabled persons. This practice can be rather helpful, especially group therapy where people with different disabilities can communicate with each other.

Obesity is a serious problem that is always present in people with Prader-Willi syndrome and needs special assistance. Lukoshe et al. (2013) believe that it is the major reason of mortality because it is extremely hard to overcome obesity that tends to progress with age. Moreover, severe obesity may cause different complications such as cardiopulmonary disorders, abnormalities of the nervous system, and diabetes mellitus. Sometimes, patients are forced to stay in special medical facilities to receive treatment and direct supervision. Hypotonia occurs in 15 percent of infants with PWS and usually lasts for two years (Cassidy et al., 2012). Therefore, Prader-Willi syndrome may have serious complications that are hard to treat and may lead to mortality and morbidity.

Evaluation

Recent studies that have made a profound research of Prader-Willi syndrome indicate that better diagnosis and treatment can improve the physical state of people who suffer from this impairment. In order to be successful in further treatment, an early diagnosis plays an important role. The main goal of various studies is to shed light on the problem, discover the treatment that can prolong their lives, and implement prevention measures to eliminate complications. In their article, Grechi et al. (2012) explain the origin of this complex genetic disorder and its influence on patients’ entire life. They argue that Prader-Willi syndrome occurs because of a hypothalamic dysfunction effected by several genes. Children with PWS start to display impairments from birth and continue to develop them during their further growth. The main complication of PWS, obesity, is a severe problem that affects patient’s life and requires proper treatment. However, the authors assume that treatment is accompanied by serious complications that do not allow therapists to reach desirable outcomes. Early diagnosis is an important helpful tool that can activate treatment, but its identification still remains a challenging task in spite of molecular testing.

Lukoshe et al. (2013) assume that there are different types of structural brain abnormalities that determine divergent genetic subtypes of Prader-Willi syndrome among children. Furthermore, they explained that children with PWS experience the deviant development of neurogenetic functions because of the impairments in brain growth. As a result, children who are affected by Prader-Willi syndrome have physical and psychological problems, such as lower their self-esteem and self-image, which decrease the quality of their life. Therefore, these individuals cannot establish healthy relationships with their peers, and they demonstrate difficulties in speaking, writing, and reading. The disease influences not only hypothalamus but also the entire central nervous system. Moreover, this syndrome prevents individuals from living a healthy, happy, and quality life. Furthermore, the scientists indicate some medicine to reduce skin picking (topiramate) and offer modafinil to treat daytime sleepiness in infants. The authors believe that children with Prader-Willi syndrome demonstrate their resistance to change, rigidity, stereotypic behavior, and impaired social functioning. Autistic traits in children with PWS is 20 to 40 times higher compared to the general population. Chromosomal rearrangement may lead to common neurodevelopmental abnormalities such as bipolar disorder and schizophrenia.

Cassidy et al. (2012) observe various complications that may occur as a result of Prader-Willi syndrome and affect persons’ life. These problems may be observed in the form of obesity, intellectual disability, characteristic facial features, genital hypoplasia, behavioral phenotype, and others. The authors believe that some of these complications can be avoided by proper diagnosis based on genetic testing and treatments. Moreover, individuals with PWS may improve their physical and psychological health through medical interventions and direct professional supervision. Although only one percent of population experiences Prader-Willi syndrome, this issue needs more research in order to help people live a healthy life, develop relationships with others, overcome depression and negative thoughts. The article indicates that modern advances in genetics give a perfect opportunity to manage this disorder by molecular genetic testing. The authors describe growth hormone replacement therapy, indicating its effectiveness. Therefore, this treatment normalizes sleep disturbances and body mass of PWS population. They also emphasize the importance of educational planning for impaired children and the ways of treatment of their behavioral problems.

Conclusion

A new understanding of the neuropathological underpinnings and genetic causes of behavioral and cognitive deficits across numerous neurodevelopmental disorders gives the awareness of the importance of revolutionary changes in behavioral genetics, molecular biology, cognitive science, developmental neurobiology, and developmental psychology. These breakthroughs have considerably altered research methodologies and conceptual frameworks, impacting individuals with Prader-Willi syndrome as well as others such as Down syndrome, autism, and dyslexia. A new paradigm has demonstrated the role of genetic factors in this disorder that are linked also with environmental variables. Prader-Willi syndrome occurs because of chromosomal anomalies and may have serious complications throughout the entire lifespan. Therefore, Prader-Willy syndrome is a result of mixed genetic and epigenetic effects that take place because of the deficiency of gene expression from the paternal chromosome at the locus q11-q13 on chromosome 15. As a result, extreme floppiness at birth determines physical, behavioral, and cognitive abnormalities that continue developing during childhood and adolescence and lead to more complex social and health problems in the future.

It is also proved that the imprinted genes play a predominant role in the development individuals with PWS, and it generates the necessity for further scientific research related to their etiology and the processes involved. Although it is a challenging task to identify the precise nature of genotype and establish the biological, physical and behavioral features, the awareness of key causes encourages a researcher to identify mechanisms responsible for this abnormality. In order to manage this disorder, individuals with Prader-Willi syndrome require early diagnoses and proper treatments.

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