Acid Ceramidase Deficiency (Farber’s Disease)
What is acid ceramidase deficiency?
Acid ceramidase deficiency, also known as Farber’s disease, is a lysosomal storage disease. Lysosomal storage diseases are inherited metabolic errors that happen because of the lack or malfunction of a particular enzyme. The enzyme is needed to break down complex chemical compounds called lysosomes, which are structures within cells that digest and recycle materials. Without the enzyme, the lysosomes are never broken down, which leads to them over-accumulating and leading to bad symptoms.
The enzyme missing in acid ceramidase deficiency is called acid ceramidase, which is found in the lysosomes and breaks down a fat called ceramide. Without ceramidase, ceramide accumulates in the lysosomes of the joints, liver, lung, nervous system, and more. This buildup causes the symptoms of the disorder, which are described below.
Acid ceramidase deficiency is a very rare disease, with only approximately 80 cases having been reported in medical literature to date. It is usually apparent at birth to the first few weeks of life, and affects males and females in equal numbers.
What are the symptoms of acid ceramidase deficiency?
Acid ceramidase deficiency is usually recognized by three characterizing symptoms:
- Painful and progressive deformity in the joints
- Nodules under the skin
- Progressive hoarseness and/or a weak cry
Other symptoms may also appear, including:
- Poor weight gain
- Difficulty breathing
- Developmental delay
- Diminished muscle tone
- Moderately enlarged liver and spleen
- Moderate swelling in lymph nodes
- Impaired vision
What causes acid ceramidase deficiency?
In this disease, the body’s inability to produce ceramidase causes painful and progressive deformity of the joints. The disorder is inherited as an autosomal recessive trait. Human traits are inherited from one’s father and mother. They each contribute a gene, which interacts with the other. In recessive disorders, the condition does not appear unless a person inherits the same mutated gene from both parents.
Researchers have determined the location of the affected gene: on chromosome 8, region 8p22-821.3. Chromosomes carry the genetic characteristics of individuals, contain thousands of genes each, and are located in the nucleus of all body cells. Human body cells normally have 23 pairs of chromosomes, so 46 chromosomes in total. Each chromosome has a short arm designated “p” and a long arm designated “q,” and then is divided even more into numbered bands. In this instance, the location of the mutated gene is a region on the short arm of chromosome 8, between bands 21.3 and 22.
The inheritance of this mutated gene is what causes acid ceramidase deficiency to develop and appear in patients.
How is acid ceramidase deficiency diagnosed?
Acid ceramidase deficiency is diagnosed using the following procedures:
- Prenatal diagnosis is possible in the fifteenth to sixteenth week of pregnancy via amniocentesis (testing cells taken from the fluid in the water sac surrounding the fetus)
- Physical exam that notices characterizing symptoms
- Genetic testing
What are the treatments for acid ceramidase deficiency?
There is no cure for acid ceramidase deficiency, so treatment focuses on pain relief and targeting specific symptoms. This includes, but is not limited to:
- Corticosteroid drugs to relieve joint pain
- Tracheostomy to assist breathing
- Bone marrow transplant to improve granulomas (small masses of inflamed tissue)
- Cosmetic surgery to remove growths in facial area
- Genetic counseling
Where can I find out more about acid ceramidase deficiency?