Malformation associated with constriction ring syndromeThe percentage of associated anomalies varies from 40% to as high as 80%
Constriction ring deformities are as common on the lower extremity as on the upper, almost all of these involve the musculoskeletal system, with clubbed feet being the most common in up to 30% of reported cases. Large reported series reveal an incidence between 5% and 15% of craniofacial malformations with clefting of the lip or palate. Prevention
Amniotic band syndrome is considered an accidental event and it does not appear to be genetic or hereditary, so the likelihood of it occurring in another pregnancy is remote. The cause of amnion tearing is unknown and as such there are no known preventative measures. Treatment
Surgical correction is recommended when a constriction ring results in a limb contour deformity, with or without lymphedema. Surgical technique
At the beginning of the surgery a tourniquet will be applied to the limb. A tourniquet compresses and controls local arterial and venous circulation for about 2 hours. The constriction band must be dissected very carefully to avoid damaging the underlying neurovasculature. When the constriction band is excised, there will be a direct closure. This allows the fatty tissue to naturally reposition itself under the skin. "With complete circumferential constriction bands, it is recommended that a two-stage correction approach be used. At the first operation, one-half of the circumference is excised and the other one-half can be excised after three to six months.
Bone marrow transplant may improve granulomas (small masses of inflamed tissue) and inflammation in patients with little or no lung or nervous system complications. Supportive therapies such as physical therapy, respiratory support, and mobility aids may be required. Studies in cells and mice have shown proof-of-concept for enzyme replacement therapy for Farber disease. Aceragen, a biopharmaceutical company, is currently developing an investigational enzyme replacement therapy with a clinical study planned for late 2022. Prognosis
Children with the most severe forms of Farber disease generally die by age 2-3 years. The life expectancy of individuals with moderate or attenuated forms is unknown. The oldest reported individuals living with Farber disease were in their 50s and 60s. Prevalence
To date, there have been approximately 200 reported cases of Farber disease and SMA-PME in the literature. The disorders are ultra-rare and estimated to occur in fewer than one per million. Eponym
It is named for Sidney Farber. References
External links
National Organization for Rare Disorders (NORD): ASAH1-Related Disorders
GeneReviews: ASAH1-Related Disorders
Aceragen Pipeline with Farber
Free Genetic Testing for ASAH1