mucopolysaccharidosis type 4A
mucopolysaccharidosis type 4AA form of mucopolysaccharidosis, an autosomal recessive lysosomal storage disease (OMIM:253000) characterised by intracellular accumulation of keratan sulfate and chondroitin-6-sulfate.
Short stature, skeletal dysplasia, dental anomalies, and corneal clouding. Intelligence is normal; no CNS involvement, except where skeletal changes compress anatomic structures and cause neurologic complications. Patients with the severe phenotype usually do not survive past the second or third decade of life.
Defects of GALNS, which encodes a sulphatase required for the degradation of glycosaminoglycans, keratan sulfate and chondroitin 6-sulfate, cause Morquio A syndrome.