Biomarker for Farber Disease - An International, Multicenter, Epidemiological Protocol

Farber disease (FD), also known as Farber's lipogranulomatosis, is an autosomal recessive lysosomal storage disease marked by a deficiency in enzyme ceramidase which causes a progressive accumulation of fatty material lipids leading to abnormalities in the joints, liver, throat, tissues and central nervous system.

FD is an extremely rare disorder, with a prevalence of less than 1/1000000. Currently only about 80 cases are reported worldwide. Disease onset is typically in early infancy but may occur later in life.

FD is caused by a mutation in the ASAH1 gene, situated on the short arm of chromosome 8. This gene codes for acid ceramidase, a lysosomal heterodimeric enzyme that hydrolyzes ceramide into sphingosine and fatty acid. To date, less than 25 distinct mutations have been identified in Farber patients, but no large deletions have yet been reported. It is inherited with an autosomal recessive pattern.

The clinical presentation of FD is characterized by the appearance of subcutaneous skin nodules, ordinarily near the joints, most often interphalangeal, wrist, elbow and ankle joints, or over points of mechanical pressure. These manifestations are very painful and lead to progressive joint stiffness, limitation of motion by contractures and finally to immobilization and deformation of joints. Also, a characteristic sign of FD is the development of a progressive hoarseness due to laryngeal involvement.

Beside these major manifestations seven phenotypes have been described which differ in severity and additional organ involvement, like the lungs, nervous system, heart and lymph nodes. Dependent on residual lysosomal ceramidase turnover, patients have a variable degree of central nervous system disease, leading to progressive neurologic deterioration. In most cases the neuronal dysfunction rather than the general physical dystrophy seems to limit the duration of FD. As well, patients with FD may die due to pulmonary disease with interstitial pneumonia.