Phenylketonuria (PKU) refers to a condition in which newborn babies lack the ability to break down a particular type of amino acid called phenylalanine. The inability to break down phenylalanine amino acids is caused by lack of enzyme phenylalanine hydroxylase. Phenylketonuria is a genetic disorder that results from mutation of a gene that renders enzyme phenylalanine hydroxylase (PAH) non-functional. Consequently, phenylalanine and other related substances accumulate within the body leading to formation of phenylpuvate, which is detected in the patient’s urine. Phenylketonuria is usually inherited form one generation to another. According to Johnston (2007), phenylketonuria develops when both parents pass on the defective gene to the baby.
If not properly treated, PKU may lead to mental retardation, epileptic seizures or fits, skin rashes, tremors and other medical complications such as abnormal neuronal activities in the brain. It may also lead to attention-deficit hyperactivity disorder (ADPH) and jerking and unusual positioning of arms. However, Johnston (2007) asserts that mental retardation is the most common complication of phenylketonuria. Phenylketonuria may be treated through restricted diets and supplementary medicines that contain amino acids.
Tay-Sachs Disease. Tay-Sachs disease is a fatal disease that affects the nervous systems of a person. Tay-Sachs disease is a genetic disorder that is passed from parents to their off-springs and it is caused by lack of a protein called hexosaminidase A in the body. Protein hexosaminidase A helps in the chemical breakdown of gangliosides and other phospholipids found in the nerve tissues. Tay-Sachs disease is caused by the presence of a defective gene on chromosome 15. According to McKenzie (2009), Tay-Sachs disease is caused by excessive accumulation of ganglioside cell membranes on nerve cells in the brains leading to insufficient activity of hexosaminidase A protein. Tay-Sachs disease usually develops when the baby is in the womb and quickly develops after birth, leading to death when the baby is 4-6 years old. A few months after birth, a baby suffering from Tay-Sachs disease usually develops more complications and dies at 4 to 6 years. Major complications of Tay-Sachs disease include inability move body parts voluntarily and epileptic seizures. There is no known treatment for the disease.
Huntington’s Disease. Huntington’s disease is a brain disorder which is caused by degeneration of nerve cells in the brain. According to Dale, Vincent and Hart (2010), the degeneration of neuron cells in the brain causes uncontrolled movements of body parts, loss of ability to think and emotional imbalances. In most cases, Huntington’s disease usually leads to serious psychiatric problems when not properly treated. Huntington’s disease may also lead to chorea, a disease characterized by abnormal involuntary writhing movements. Physical symptoms of Huntington’s disease usually begin when the patient reaches 35 years. These symptoms often disappear and reoccur later in life. Repeated occurrence of symptoms often leads to more serious complications, such as reduced cognitive ability, loss of memory, poor coordination of body muscles, slurred speech and choking during meals.
McKenzie (2009) asserts that the greatest risk faced by patients of Huntington’s disease in pneumonia. Pneumonia is believed to be the greatest cause of most deaths in patients of Huntington’s disease. Moreover, patients may also suffer from heart attacks. Other life-threatening complications include physical injuries resulting from frequent falls, malnutrition, anemia and suicide deaths.