Alpha-mannosidosis: a diagnostic journey in patients with ultra-rare disease

Moiseev S.: Tareev Clinic of Internal Diseases, Sechenov First Moscow State Medical University, Moscow, Russia

Novikov P.: Tareev Clinic of Internal Diseases, Sechenov First Moscow State Medical University, Moscow, Russia

Moiseev A.: Sechenov First Moscow State Medical University

Sholomova V.: Sechenov First Moscow State Medical University

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Summary

Alpha-mannosidosis is a rare autosomal recessive hereditary disease characterized by lysosomal accumulation of olygosaccharides in various tissues due to deficiency of alpha-mannosidase. Low enzyme activity results from homozygous or compound heterozygous mutations of the MAN2B1 gene. Clinical manifestations of alpha-mannosidosis usually develop in childhood or adolescence and include facial deformity (Hurler-like phenotype), mental retardation, progressive sensorineural hearing loss, skeletal abnormalities, neurological and psychiatric disorders, and ocular disease. Demonstration of low activity of acid alpha-mannosidase in dried blood spots and genetic testing can be used for diagnosis. The authors present the case report of alpha-mannosidosis and discuss its pathogenesis, clinical signs and symptoms and approaches to treatment including the long-term enzyme replacement therapy with velmanasa alfa.

Key words

Lysosomal storage diseases, alpha-mannosidosis, velmanase alfa.