Alpha-Mannosidosis in a 3.5-Year-Old Girl: A Case Report.

Authors

Samuel Bonilla Fornes, Maria Pilar Mendez Perez, Marta Torres Diaz, Maria Eugenia Sanchez Gutierrez, Enrique Galán Gómez

Published in

Clinical case reports. Volume 14. Issue 8. Pages e73276. Epub Aug 04, 2026.

Abstract

Alpha-mannosidosis is a rare lysosomal storage disease caused by a deficiency of the enzyme alpha-mannosidase. It manifests as a continuous spectrum of signs and symptoms characterized by dysmorphic features, skeletal abnormalities, delayed psychomotor and speech development, impaired hearing, and psychiatric involvement. When suspected, alpha-mannosidosis must be confirmed by biochemical and molecular testing, namely, assessment of blood levels of alpha-mannosidase in leukocytes or fibroblasts and Sanger or next-generation sequencing of the MAN2B1 gene. The disease must be diagnosed and treatment started as quickly as possible, since the long-term prognosis for untreated patients is very poor. Enzyme replacement therapy (ERT, human recombinant alpha-mannosidase) has replaced allogeneic stem cell transplant as the mainstay of therapy, thus improving disease-related outcomes with, for example, reduced serum oligosaccharide levels, greater functional capacity, and improved quality of life, all with a good safety profile. We report the seventh case of alpha-mannosidosis in Spain. The patient was a 3.5-year-old girl assessed in the clinical genetics department for developmental delay and marked dysmorphic features (trigonocephaly, exophthalmos, hypertelorism, and a flat nasal bridge). Radiography revealed shortening and thickening of the long bones, as well as metopic and coronal synostosis. Craniosynostosis was treated with surgery. Assessment of alpha-mannosidase revealed complete absence of enzymatic activity. Genetic analysis revealed the homozygous pathogenic variant of MAN2B1, c.2248C>T, which is associated with alpha-mannosidosis. ERT is the only currently available pharmacological option for treating children with mild-to-moderate alpha-mannosidosis. Without ERT, patients' quality of life would be impaired, and their prognosis would worsen significantly.

PMID:
42553539
Bibliographic data and abstract were imported from PubMed on 05 Aug 2026.

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