Aspartylglycosaminuria is an inborn error of metabolism caused by deficient activity of the enzyme aspartylglucosaminidase. Clinical manifestations consist of psychomotor retardation, coarse facies, hepatosplenomegaly, ventral hernia and skeletal abnormalities.

Pathophysiology

Deficiency of the aspartylglucosaminidase (1-aspart-amido-beta-N-acetylglucosamine aminohydrase (E.C.3.5.1.26), an enzyme which cleaves the N-acetyl-glucosamine-asparagine linkage of oligosaccharide chains in glycoprotein and glycopeptide metabolism. Biochemical tests show high urinary levels of aspartylglucosamine and low activity of aspartylglucosaminidase.

Epidemiology

Originally, most early patients were of Finnish ancestry but later cases were reported in other groups. After trisomy 21 and fragile X syndrome, this is the most frequent multiple congenital anomaly/mental retardation syndrome. A child with Down syndrome Down syndrome (also called Downs syndrome) encompasses a number of genetic disorders, of which trisomy 21 (a nondisjunction) is the most representative, causing highly variable degrees of learning difficulties and physical disabilities. ... Fragile X Syndrome is the most common inherited cause of mental retardation, and is associated with autism. ...