Arylsulfatase B deficiency
Arylsulfatase B deficiency
Description, Causes and Risk Factors:
An error of mucopolysaccharide metabolism characterized by excretion of dermatan sulfate in the urine, growth retardation, lumbar kyphosis, sternal protrusion, genu valgum, usually hepatosplenomegaly, and no mental retardation; onset occurs after 2 years of age; autosomal-recessive inheritance, caused by mutation in the arylsulfatase B gene (ARSB) on chromosome 5q.
Arylsulfatase B deficiency is a lysosomal storage disease with progressive multisystem involvement, associated with a deficiency of arylsulfatase B (ASB) leading to the accumulation of dermatan sulfate. Birth prevalence is between 1 in 43,261 and 1 in 1,505,160 live births. The disorder shows a wide spectrum of symptoms from slowly to rapidly progressing forms.
The disorder is transmitted in an autosomal-recessive manner and is caused by mutations in the ARSB gene, located in chromosome 5 (5q13-5q14). Over 130 ARSB mutations have been reported, causing absent or reduced arylsulfatase B (ASB or N-acetylgalactosamine-4-sulfatase) activity and interrupted dermatan sulfate and chondroitin sulfate degradation.
The arylsulfatase B deficiency is very rare disease, not more than 18 cases have been reported.
The characteristic skeletal dysplasia includes short stature, dysostosis multiplex and degenerative joint disease. Rapidly progressing forms may have onset from birth, elevated urinary glycosaminoglycans (GAG, generally >100 microgram/mg creatinine), severe dysostosis multiplex, short stature, and death before the 2nd or 3rd decades. A more slowly progressing form has been described as having later onset, mildly elevated glycosaminoglycans (generally <100 mcg/mg creatinine), mild dysostosis multiplex, with death in the 4th or 5th decades. Other clinical findings may include cardiac valve disease, reduced pulmonary function, hepatosplenomegaly, sinusitis, otitis media, hearing loss, sleep apnea, corneal clouding, carpal tunnel disease, and inguinal or umbilical hernia.
Diagnosis generally requires evidence of clinical picture, ASB activity of less than 10% of the lower limit of normal in cultured fibroblasts or isolated leukocytes, and demonstration of a normal activity of a different sulfatase enzyme. The finding of elevated urinary dermatan sulfate with the absence of heparitin sulfate is supportive. In addition to multiple sulfatase deficiency, the differential diagnosis should also include other forms of MPS (MPS 1, 2, 4A, 7), sialidosis and mucolipidoses.
Before enzyme replacement therapy (ERT) with galsulfase (NaglazymeTM), clinical management was limited to Supportive care and hematopoietic stem cell transplantation. Galsulfase is now widely available and is a specific therapy providing improved endurance with an acceptable safety profile. Prognosis is variable depending on the age of onset, rate of disease progression, age at initiation of ERT and on the quality of the medical care provided.
NOTE: The above information is educational purpose. The information provided herein should not be used during any medical emergency or for the diagnosis or treatment of any medical condition.
DISCLAIMER: This information should not substitute for seeking responsible, professional medical care.
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