PhenylketonuriaPhenylketonuria

Introduction

• Phenylketonuria (PKU) autosomal recessive disorder characterized by an inability of the body to utilize the essential amino acid, phenylalanine.

• Located On The 12th chromosome

• It is an inherited disorder that increases the levels of a substance called phenylalanine in the blood.

Phenylalanine is a building block of proteins (an amino acid) that is obtained through the diet. It is found in all proteins and in some artificial sweeteners. If PKU is not treated, phenylalanine can build up to harmful levels in the body, causing intellectual disability and other serious health problems.

Tyrosine is a nonessential amino acid the body makes from another amino acid called phenylalanine. It is a building block for several important brain chemicals called neurotransmitters, including epinephrine, norepinephrine, and dopamine. Neurotransmitters help nerve cells communicate and influence mood. Tyrosine also helps produce melanin, the pigment responsible for hair and skin color. It helps in the function of organs responsible for making and regulating hormones, including the adrenal, thyroid, and pituitary glands. It is involved in the structure of almost every protein in the body.

• Because tyrosine is made from phenylalanine, people with PKU can be deficient in tyrosine. Tyrosine is used in protein supplements for people with PKU, but most doctors don't recommend more tyrosine supplements. If you have PKU, your doctor will determine if you need more tyrosine and how much.

Dietary Sources:• Tyrosine is found in soy products, chicken, turkey, fish, peanuts, almonds,

avocados, bananas, milk, cheese, yogurt, cottage cheese, lima beans, pumpkin seeds, and sesame seeds.

PHENYLKETENURIA

Characteristics

• Undistinguishable until years after birth

• Due to its autosomal receive inheritance pattern it is rarely able to be diagnosed by genetic screening.

• There is current no cure.

Facts

• Classic PKU and the other causes of hyperphenylalaninemia 5260 people a year. Caucasian or Oriental births. The incidence in African Americans is far less. These disorders are equally frequent in males and females.

SIGNS AND SYMPTOMS• Infants with classic PKU appear normal until they are a few

months old.

• Without treatment with a special low-phenylalanine diet, these children develop permanent intellectual disability.

• Seizures, delayed development, behavioral problems, and psychiatric disorders.

• Untreated individuals may have a musty or mouse-like odor as a side effect of excess phenylalanine in the body.

• Children with classic PKU tend to have lighter skin and hair than unaffected family members and are also likely to have skin disorders such as eczema.

• Less severe forms of this condition, sometimes called variant PKU and non-PKU hyperphenylalaninemia, have a smaller risk of brain damage. People with very mild cases may not require treatment with a low-phenylalanine diet.

• These infants may also have a low birth weight and grow more slowly than other children.

• Other characteristic medical problems include heart defects or other heart problems, an abnormally small head size (microcephaly), and behavioral problems.

• Women with PKU and uncontrolled phenylalanine levels also have an increased risk of pregnancy loss.

Life Impact

• Delayed mental and social skills• Seizures• Jerking movements of the arms or legs• Tremors• Serious rashes• Attention-deficit hyperactivity disorder• Severe mental retardation

DIAGNOSIS

• PKU can be easily detected with a simple blood test. All states in the US require a PKU screening test for all newborns as part of the newborn screening panel. The test is generally done by taking a few drops of blood from the baby before the baby leaves the hospital.

• If the initial screening test is positive, further blood and urine tests are required to confirm the diagnosis.

Screening Methods

• Screening for PKU is mandated in all 50 states. Performed after 24 hours of life but before the infant is 7 days old.

• There are three principal methods used for PKU screening the Guthrie Bacterial Inhibition Assay (BIA), automated fluorometric assay, and tandem mass spectrometry.

• Unfortunately not everybody has the resources for these tests.

TREATMENT• Treatment involves a diet that is extremely low in

phenylalanine, particularly when the child is growing. The diet must be strictly followed. This requires close supervision by a registered dietitian or doctor, and cooperation of the parent and child. Those who continue the diet into adulthood have better physical and mental health. “Diet for life” has become the standard recommended by most experts. This is especially important before conception and throughout pregnancy.

• A special infant formula called Lofenalac is made for infants with PKU. It can be used throughout life as a protein source that is extremely low in phenylalanine and balanced for the remaining essential amino acids

Work Cited• http://www.medhelp.org/lib/pku.htm

• http://www.nlm.nih.gov/medlineplus/phenylketonuria.html

• http://www.pkunews.org/

• http://www.umm.edu/altmed/articles/tyrosine-000329.htm#ixzz2NtxtlE41