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Alpha‐mannosidosis (AM) is a rare, autosomal recessive, lysosomal storage disorder caused by alpha‐mannosidase deficiency that leads to the accumulation of mannose‐rich oligosaccharides. AM symptoms and severity vary among individuals; consequently, AM is often not diagnosed until late childhood. Velmanase alfa (VA), a recombinant human lysosomal alpha‐mannosidase product, is the first enzyme replacement therapy indicated to treat non‐neurological symptoms of AM in Europe. Previous studies suggested that early VA treatment in children may produce greater clinical benefit over the disease course than starting treatment in adolescents or adults; however, long‐term studies in children are limited, and very few studies include children under 6 years of age. The present phase 2, multicenter, open‐label study evaluated the safety and efficacy of long‐term VA treatment in children under 6 years of age with AM. Five children (three males) received VA weekly for ≥24 months, and all children completed the study. Four children experienced adverse drug reactions (16 events) and two experienced infusion‐related reactions (12 events). Most (99.5%) adverse events were mild or moderate, and none caused study discontinuation. Four children developed antidrug antibodies (three were neutralizing). After VA treatment, all children improved in one or more efficacy assessments of serum oligosaccharide concentrations (decreases), hearing, immunological profile, and quality of life, suggesting a beneficial effect of early treatment. Although the small study size limits conclusions, these results suggest that long‐term VA treatment has an acceptable safety profile, is well tolerated, and may provide potential benefits to patients with AM under 6 years of age. [ABSTRACT FROM AUTHOR]

Methylmalonic acidemia with homocystinuria, cobalamin deficiency type C (cblC) (MMACHC) is the most common inborn error of cobalamin metabolism. Despite a multidrug treatment, the long-term follow-up of early-onset patients is often unsatisfactory, with progression of neurological and ocular impairment. Here, the in-vivo proteome of control and MMACHC lymphocytes (obtained from patients under standard treatment with OHCbl, betaine, folate and L-carnitine) was quantitatively examined by two dimensional differential in-gel electrophoresis (2D-DIGE) and mass spectrometry. Twenty three proteins were found up-regulated and 38 proteins were down-regulated. Consistent with in vivo studies showing disturbance of glutathione metabolism, a deregulation in proteins involved in cellular detoxification, especially in glutathione metabolism was found. In addition, relevant changes were observed in the expression levels of proteins involved in intracellular trafficking and protein folding, energy metabolism, cytoskeleton organization and assembly. This study demonstrates relevant changes in the proteome profile of circulating lymphocytes isolated from treated cblC patients. Some results confirm previous observations in vivo on fibroblast, thus concluding that some dysregulation is ubiquitous. On the other hand, new findings could be tissue-specific. These observations expand our current understanding of the cblC disease and may ignite new research and therapeutic strategies to treat this disorder. [ABSTRACT FROM AUTHOR]