Adrenoleukodystrophy: Causes, Symptoms, Diagnosis, and Treatment

Adrenoleukodystrophy is a genetic disorder that occurs because of the accumulation of a very long chain of fatty acids throughout the body mainly in the central nervous system, testes, and adrenal glands. It occurs mainly because of a mutation of the ABCD1 gene. Affects the myelin layer which is the covering layer of the nerves and protects the nerve, hence when this myelin layer is damaged it affects the signals carried through the nerve from the brain to the other parts of the body. It is X linked disease that runs in families and hence affects mainly men and the females are just carriers.

The disease usually presents with no or minimal symptoms. Presentation depends on the type of adrenoleukodystrophy. There are 3 types of Adrenoleukodystrophy.

• Cerebral type mainly affects the child of age group 4 to 8yrs.

• Adrenomyeloneuropathy type affects the adult age group and occurs slowly over several years, it presents with stiffness while walking and can also present with bowel and bladder types.

• Adrenal type is characterized by insufficient production of the adrenal hormones; cortisol and aldosterone. It is also known as Addison’s disease.

Adrenoleukodystrophy progresses slowly over time. It can affect the individual both physically and mentally. Cerebral type is a very serious one it can cause the child to go into a coma and after several years of coma, it can lead to the death of a child.

Adrenoleukodystrophy: Causes

Adrenoleukodystrophy is a hereditary disorder that runs in families, transferred from parents to children. It is an X-linked autosomal recessive disorder hence mainly affecting male and female carriers.

It is caused by the mutation of the ABCD1 (ATP binding cassette, sub-family D) gene. This gene has control over the adrenoleukodystrophy protein. ALD protein helps in the oxidation of the very long chain fatty acids in the peroxisomes by various chemical reactions and helps in breaking the very long chain fatty acids.

When the ABCD1 gene maintaining this is mutated, it causes a shortage of Adrenoleukodystrophy protein which results in the accumulation of very long-chain fatty acids

Adrenoleukodystrophy: Symptoms

The symptoms of Adrenoleukodystrophy depend on the type of Adrenoleukodystrophy the patient has developed.

Cerebral type of Adrenoleukodystrophy presents with the following symptoms −

• Spasms of the muscles

• Seizure attacks

• Difficult in swallowing

• Loss of hearing

• Difficulty with sentence formation

• Disturbances of vision

• Hyperactivity

• Weakness or paralysis

• Coma

• Deterioration of fine motor control

• Crossing of the eyes(squint)

Adrenomyloneuropathic type of Adrenoleukodystrophy presents with the following symptoms −

• Stiffness while walking

• Weakness of the muscles

• Bowel and bladder dysfunction causing poor control of urination

• Difficulty in thought process and remembering the already-seen objects

Adrenal insufficiency type of Adrenoleukodystrophy presents with the following symptoms −

• Loss of appetite

• Loss of weight

• Decreased mass of the muscles

• Vomiting

• Weakness of muscles

• Coma

• Increased pigmentation of the skin

Adrenoleukodystrophy: Risk Factors

The risk factors of Adrenoleukodystrophy include −

• Familial − It runs in the families transferred from the parents to the children.

• Sex − Males are affected and females are carriers as it is X linked.

Adrenoleukodystrophy: Diagnosis

The diagnosis of adrenoleukodystrophy is done by the clinical presentation and some investigations are required which include −

• Blood levels of the very long chain fatty acids

• Genetic tests are done to check the mutations of the ABCD1 gene

• Magnetic resonance imaging − This test is done to check the damage to the brain’s white matter. It helps in diagnosing the disease in the early stage.

Adrenoleukodystrophy: Treatment

There is no exact treatment for the disease. Some treatments can prolong the disease's course and reduce the severe complications that occur in the future. These treatment modalities include −

• Dietary therapy − The patient is advised to take a diet that has low long-chain fatty acids.

• Gene therapy − in this the gene vectors which express the ABCD1 gene into the patients

• Special oils − such as Lorenzo oil can help to prolong the occurrence of the disease

• Bone marrow transplantation − Allogenic hematopoietic bone marrow transplantation can be done if the disease is present at the age.

• Symptomatic therapy − Treatment of the symptoms such as seizures should be done.

• Physical therapy − used to reduce the stiffness of the muscles

Adrenoleukodystrophy: Prevention

There are no preventive measures to prevent the occurrence of the disease. Genetic counseling can be done in families who have a history of adrenoleukodystrophy. The presence of the disease can be diagnosed based on genetic counseling and parents can be known about the disease involving the child

Conclusion

Adrenoleukodystrophy is a type of genetic disease that runs in families affecting men and women being the carriers. It is Xlinked disorder carried by the X chromosome to the next generation. It is caused by the mutation of the ABCD1 gene which controls the adrenoleukodystrophy gene which is responsible for the breakage of the bond of very long chain fatty acids. Hence when mutated causes the accumulation of very long chain fatty acids in the various parts of the body mainly in the central nervous system, testes, and adrenal gland.

The myelin layer of the nerve which is the covering protective layer of the nerves is damaged resulting in disturbance of the transfer of the nerve signals from the brain to the other parts of the body is affected. The symptoms and clinical presentation depending on the type of the adrenoleukodystrophy. Cerebral type mainly affects the child and can cause death. Adrenomyeloneuropathy type and adrenal insufficiency type affects usually adults

The disease is a slow process that occurs over years to develop. It should be diagnosed early as it is life-threatening and causes severe complications, diagnosis is done through various blood tests, genetic studies, and MRIs. There is no cure for this disease but the course of the disease can be prolonged by taking a diet containing low long-chain fatty acids, symptomatic support, physical therapy, genetic therapy and by bone marrow transplantation.