Introduction
Amino acids are a group of 20 different molecules that are used to form proteins. Nine of the amino acids are known as essential amino acids. Some of these essential amino acids are histidine (help make brain chemical), isoleucine (it is involved in muscle metabolism and immune function), leucine (it helps in making protein and growth hormones), and lysine (it helps in the production of hormones and also essential for immune and calcium functions in the body).
What Is Familial Hyperlysinemia?
Familial hyperlysinemia is also known as an alpha-aminoadipic semialdehyde deficiency disease, saccharopine urea, and hyperlysinemia. It is an inherited disorder that leads to elevated levels of amino acid lysine. Lysine acts as the building block of almost all proteins. The high level of lysine does not affect an individual’s health and is left undiagnosed for a long time. The symptoms may start appearing at any point in life.
What Causes Familial Hyperlysinemia?
It is an inherited autosomal recessive condition meaning that the affected individual has two copies of the gene in each cell that has the mutation. The parents carry a copy of each defective gene that is passed on to the child. If a child inherits one copy of the defective gene, then it becomes a carrier, which means that individuals can pass on the condition to their children. The chances of passing it increase by 50 percent with each pregnancy.
Familial hyperlysinemia is caused due to a gene mutation. Mutation in the AASS gene is the main cause of this condition.
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AASS Gene: This gene gives instructions to make the aminodipic semialdehyde synthase enzyme. It is present in many tissues and is mainly found in the liver. This enzyme breaks down the lysine. Around five mutations in the AASS gene lead to familial hyperlysinemia. The single aminoadipic semialdehyde synthase changes due to mutation and decreases the enzyme activity which leads to an inability to break down the lysine. The impaired breakdown of saccharopine builds up the molecule in the blood and urine.
What Are the Clinical Features of Familial Hyperlysinemia?
Some of the common symptoms include:
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Intellectual disability.
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Muscular hypotonia (abnormally low muscle tone, especially in infants).
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Delayed speech development in children.
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Behavioral abnormality or psychiatric disturbances.
How Is Familial Hyperlysinemia Diagnosed?
Some of the testing methods include:
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Genetic Testing - It examines the DNA (deoxyribonucleic acid), which is a database that carries instructions for the body’s functions. It is always informed before genetic testing that, in some cases, the negative result does not confirm the diagnosis, and the test can be performed again. The blood test is done by a healthcare expert who takes the blood from the arm’s vein, and the sample is sent to the laboratory for further testing. The genetic test helps in getting a proper diagnosis of familial hyperlysinemia.
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Blood Test - A blood test is done to check the level of lysine in the blood. A healthcare professional will take the blood sample from the arm’s vein. A fine needle is inserted into the vein, and a small amount of blood is drawn out. The sample is collected in a vial or a test tube. The blood sample is sent to a laboratory for further investigation.
How Is Familial Hyperlysinemia Managed?
The symptoms can be controlled by the following methods:
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Speech therapy can be given to children who have difficulty speaking and communicating.
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Genetic counseling can be given to the patient’s family to make them understand the severity of the condition and also helps to make the family planning decision. It will be conducted by an expert who will guide and explain the condition's long-term and short-term features and the risk of recurrence in family members.
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In children who face delayed motor development, occupational therapy is done. It helps the child to enhance motor skills.
Conclusion
Familial hyperlysinemia is a rare inherited disorder that is passed on to a child from the parents. It is a disorder that elevated levels of lysine amino acids which is one of the main building blocks for almost all amino acids. This condition does not affect any organs or any other complications. It can be diagnosed by taking a blood or genetic test. Once the condition is detected the symptoms can be controlled by giving proper therapies and counseling.
