HSN107 Physiology Of Human Growth And Development

The genetic disorder “Phenylketonuria (PKU)”

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Executive Summary

Phenylketonuria (PKU) is a fatal disease inherited by parents and this can be created by genetic mutations. This is genetic incapability to metabolize phenylalanine that can destroy the life of an individual by brain and nerve damage. The disease is rare and it can pose life-threatening challenges. It is caused by a malfunction in the gen that helps in the formulation of the enzyme required to break down the element: phenylalanine. If the disease is not identified at an early stage and if it remains neglected, it can cause death. Various neurological and psychiatric disorders, behavioural issues can be seen in the patients. Pregnant women and newborns may be the victims of the disease due to the uncontrolled presence of protein in the blood. The disease can be diagnosed by providing the perfect nutritional therapy and proper diet. The various forms of the disease can be caused by the autosomal recessive manner. Many countries take the initiative of screening programmers and campaigns to increase awareness about the disease. Treatment must follow a diet that consists of low protein and a balanced amount of all the elements that is necessary for growth.

Table of Contents

Introduction. 4

Discussion. 4

Prevalence. 4

Genetic Mutation. 4

Clinical symptoms. 5

Diagnosis. 6

Nutritional management 7

Conclusion. 7

References. 8

Introduction

PKU is a genetic disorder that most of the time comes from heredity and that identifies the increased presence of phenylalanine in the blood. The diet provides the block of proteins that is phenylalanine found in artificial sweeteners. Without proper treatment, this disease can turn out detrimental and life-threatening for the patients. The victims can be exposed to intellectual disability and other associated health hazards that will invite danger to the person and the family. Even newborn babies can experience this disease and suffer brain damage because of the high level of proteins that cannot be controlled at all.

Discussion

Prevalence

Women with uncontrolled PKU experience pregnancy loss and many infants may have the risk of low weight and lost capacity of understanding. Delayed development, seizures, behavioural issues and other related psychiatric imbalance are so prevalent. As the nerve cells are sensitive to the phenylalanine levels, excessive presence of that component can reach up to the toxic level and create hazards (Cazzorla et al., 2018). The particular substance prevents the enzyme to convert the amino acid to other compounds and the creation of other enzymes. Phenylketonuria can be caused by the mutations in the PAH gene that will make for some of the enzymes to carry on with their activities resulting in milder versions of the disease.

Genetic Mutation

PKU is caused by the genetic alterations in the PAH gene. The hereditary error in metabolism is caused if the gene is malfunctioning. The breaking down of phenylalanine gets problematic with the gene mutation. If it cannot break down, the body cannot build protein which is helped by Amino acids. The nerve cells in the brain start deteriorating when the enzymes converting amino acids get excessive to create damages to body parts (Nelwan, 2020). The recessive pattern continues when a child received the disease from the parent. Sometimes, a parent is just the carrier of the disease, which defines the patient carrying the mutated PAH gene. The child will not be contracted the disease if the mutated gene is carried by only one parent. However, a 50% chance is that a child will acquire one abnormal gene from one parent and the other normal from the one, making the child carrier. Some mutations are intensive and some are silent.

Clinical symptoms

The greatest symptoms can be found in the metabolically abnormalities and the hampered metabolism reduces the capabilities of food digestion. The disorders happen to such a degree that they can lead to neurological problems and if neglected, it cans a serious issue to the victims. The most severe form is the classic PKU, where children develop a permanent intellectual disorder. Adults grow pale skin and hair at times fatal skin diseases like eczema. The other symptom that an individual can grow is the mouse or musty like odour as aid effect of the disease (Pugliese et al., 2020).

Babies of newly born mothers with PKU go through severe heart disease at that tender phase as they have already inherited high levels of phenylalanine from birth. Many children show slow development growth compared to the other children. Heart defects can grow at an accelerated rate and other heart problems can be seen in adults. Many children can grow abnormally small head size. The inheritance is attained through an autosomal recessive pattern where the inborn get the abnormal gene from the parent. Therefore, the symptoms can be hyperactivity, emotional and behavioural issues that can be a major issue of concern.

Complications during birth can involve facial abnormalities and other adaptive issues. Phenylalanine cannot transform to melanin, the pigment causes hair and skin disorders. Depression and mental retardation are very common causes that harm society. Fatigue, nausea and the central nervous system damage due to the injury created by phenylalanine. Tremor, involuntary aggressiveness, unusual postures are the prominent signs that can be present in the patients.

Diagnosis

The elevated level of phenylalanine depends on enzyme efficiency in a patient. The diagnosis must focus on a proper diet that wills priorities protein synthesis. Infants with plasma concentration must be treated with care keeping in mind that phenylalanine must be ingested in the diet, not made in the body (Woolf & Adams, 2020). As there is a chance of damage to the liver and kidney, intake of food must follow a healthy pattern that will also raise the level of tyrosine. Proper diagnosis should be initiated by tasting the pregnant mother and the baby after birth to address the gene mutations. The doctor can suggest the safe amount of phenylalanine through the following ways:

• The screening of newborns must take place for the identification of PKU.
• Laboratories must collect the blood of babies and sometimes the blood test is conducted through a heel stick within 48 hours of birth.
• Consistent review of the growth chart, diet records, and blood level must be conducted.
• As the level of phenylalanine can change frequently, during childhood development and even pregnancy, recurrent blood tests are mandatory.
• Other additional blood and more urine tests to assess health recovery and development are needed.
• The medications that have excessive elements of aspartame, vitamins must be avoided. The Food and Drug Administration approves the use of the drug sapropterin in PKU treatment.
• Another possible treatment can be amino acid therapy in tablets or powdered from. That can prevent the generation of phenylalanine.

Nutritional management

 Infants must be offered phenylalanine-free food and even a dietician must carefully determine how much breast milk might be given. Certain foods like potatoes, grains, cheese, fish and pork, chicken, beans of high proteins and excessive vitamins and diet soda, other drinks must be avoided (Alptekin et al., 2018). The registered dietician must offer sufficient help in addressing the challenges to proper diet and medication that will ensure that every individual must take the amount of phenylalanine that is only crucial for health.

Conclusion

Adolescents and adults can intake food rich in essential amino-acid without that particular component. Families must play a big role in finding the right nutritional supplement for the patients which can be challenging at times.The perfect nutritional management should consist of the limited food options for a healthy life.

References

Alptekin, I. M., Koc, N., Gunduz, M., & Cakiroglu, F. P. (2018). The impact of phenylketonuria on PKU patients’ quality of life: using of the phenylketonuria-quality of life (PKU-QOL) questionnaires. Clinical nutrition ESPEN, 27, 79-85. Rtrived from: https://www.sciencedirect.com/science/article/pii/S221442692030017

Cazzorla, C., Bensi, G., Biasucci, G., Leuzzi, V., Manti, F., Musumeci, A., … & Burlina, A. (2018). Living with phenylketonuria in adulthood: the PKU ATTITUDE study. Molecular genetics and metabolism reports, 16, 39-45. Retrieved from: https://www.sciencedirect.com/science/article/pii/S221442691830065X

Nelwan, M. (2020). Phenylketonuria: Genes in phenylketonuria, diagnosis, and treatments. African Journal of Biological Sciences, 2(1), 1-8. Retrieved from: https://www.tandfonline.com/doi/pdf/10.1080/15476278.2021.1949865

Pugliese, M., Tingley, K., Chow, A., Pallone, N., Smith, M., Rahman, A., … & Potter, B. K. (2020). Outcomes in pediatric studies of medium-chain acyl-coA dehydrogenase (MCAD) deficiency and phenylketonuria (PKU): a review. Orphanet journal of rare diseases, 15(1), 1-15. Retrieved from: https://link.springer.com/article/10.1186/s13023-019-1276-1

Woolf, L. I., & Adams, J. (2020). The early history of PKU. International Journal of Neonatal Screening, 6(3), 59. Retrieved form: https://ojrd.biomedcentral.com/articles/10.1186/s13023-019-1153-y