Galactosialidosis

Galactosialidosis (also Goldberg syndrome or β -galactosidase - neuraminidase deficiency ) is a rare autosomal recessive lysosomal storage disease belonging to the group of oligosaccharidoses.

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Etiology

The cause of the galactosialidosis is a greatly reduced activity of the enzymes α -D and β -galactosidase Neurominidase caused by a defect of the bi- functional protein Protective protein / cathepsin A ( PPCA ) ( " protective protein" ) is caused. Along with neuraminidase and β -galactosidase is the PPCA a multi-enzyme complex, the PPCA stabilizes these two enzymes in an acidic environment, thus ensuring their activity in the lysosome. The PPCA regulated intracellular transport. The stabilization of β -galactosidase is performed by an aggregation of the individual β -galactosidase units in high molecular weight multimers. Mutations in the coding PPGB the PPCA gene cause a loss of function, or a restriction of the function of the gene product PPCA. These are mostly missense mutations. However, it was described abnormal splicing of the mRNA by modification of the splice sites as the cause. The affected PPGB gene is located on chromosome 20 locus 13.1.

Symptoms and diagnosis

In clinical practice, there are three phenotypes of galactosialidosis:

• Congenital or early - infantile form
• The late infantile
• The juvenile / adult form

Congenital or early - infantile form is characterized by edema, abdominal dropsy ( ascites), enlargement of the liver and spleen ( hepatosplenomegaly ), chronic renal failure, various neurological symptoms (such as mental retardation ), deformations of the face and skeletal abnormalities characterized. In the macula can usually find a cherry-red spot, the disease leads to early blindness. Prenatal the galactosialidosis manifest as hydrops fetalis. The life expectancy is in this phenotype one year and less.

In the late - infantile form of the psychic abilities are hardly or not at all restricted. Affected children often reach only the second decade of life.

In the juvenile / adult form that occurs in Japan, in essence, the disease course is progressive slow. Deformations of the face, dysostosis multiplex and angiokeratoma are here with corneal opacities and the cherry-red spot in the macula, the primary symptoms. Patients with this phenotype reach adulthood.

Affected patients excrete increased amounts of oligosaccharides in the urine. These can be detected by thin layer chromatography. The activity of the affected enzymes can be determined in fibroblasts and trophoblasts (prenatal ).

Treatment and prognosis

There is currently no known causal therapy. Treatment is symptomatic.

First description

The galactosialidosis was first described in 1971 by the U.S. ophthalmologists Morton F. Goldberg. The Goldberg syndrome must be distinguished from Shprintzen Goldberg syndrome, another - is disease - Marfan syndrome very similar.