Musings on genome medicine: enzyme-replacement therapy of the lysosomal storage diseases

Iduronate-2-sulfatase interactome: Validation by Yeast Two-Hybrid Assay

Mucopolysaccharidosis type II (MPS II), also known as Hunter syndrome, is a rare X-linked recessive disease caused by a deficiency of the lysosomal enzyme iduronate-2-sulfatase (IDS), which activates intracellular accumulation of nonmetabolized glycosaminoglycans such as heparan sulfate and dermatan sulfate. This accumulation causes severe damage to several tissues, principally the central nervous system. Previously, we identified 187 IDS-protein interactions in the mouse brain. To validate a subset of these interactions, we selected and cloned the coding regions of 10 candidate genes to perform a targeted yeast two-hybrid assay. The results allowed the identification of the physical interaction of IDS with LSAMP and SYT1. Although the physiological relevance of these complexes is unknown, recent advances allow us to point out that these interactions could be involved in vesicular trafficking of IDS through the interaction with SYT1, as well as to the ability to form a transcytosis module between the cellular components of the blood-brain-barrier (BBB) through its interaction with LSAMP. These results may shed light on the role of IDS on cellular homeostasis and may also contribute to the understanding of MPS II physiopathology and the development of novel therapeutic strategies to transport recombinant IDS through the brain endothelial cells toward the brain parenchyma.

The special case of gene therapy pricing

Gene therapy companies that pursue high, one-time payments for their products risk a backlash from payors. A better solution may lie in a pay-for-performance model.

Different Pathways to the Lysosome: Sorting out Alternatives

Considerable research supports a model in which hydrolytic enzymes of mammalian lysosomes are sorted to their destinations in a receptor-dependent mechanism. The ligand for the mammalian sorting receptors is mannose 6-phosphate (M6P). Two M6P receptors have been defined in mammals. Here, we review the foundational evidence supporting this mechanism and highlight the remaining gaps in our understanding of the mammalian mechanism, including evidence for M6P-independent sorting, and its relevance to lysosomal enzyme sorting in metazoa.

A clinical multicenter study of orofacial features in 26 brazilian patients with different types of mucopolysaccharidosis

PURPOSE

This study aimed to describe the orofacial features of 26 unrelated Brazilian patients with mucopolysaccharidosis and to verify any possible associations between these findings and specific types of mucopolysaccharidosis.

METHODS

Patients were diagnosed with mucopolysaccharidosis and clinically evaluated. Following consent, a clinical assessment form was completed. Facial and intraoral examination was performed by evaluating facial pattern, malocclusions, dental caries, and tooth identification.

RESULTS

Midface deficiency, increased lower facial third, anterior open bite, convex profile, macroglossia, gingival enlargement, and spaced arches were the most frequently observed features. These findings did not allow a differential diagnosis among the different types of mucopolysaccharidosis, except for pitting enamel, which significantly associated with mucopolysaccharidosis IVA (P < .001). Open bite was associated with mucopolysaccharidosis types I, II, III, and VI; however, only one patient with mucopolysaccharidosis IVA expressed this feature (P = .043).

CONCLUSIONS

Our results suggest that pitted enamel in patients with mucopolysaccharidosis is most likely a feature of mucopolysaccharidosis type IVA; whereas, open bite is rarely observed in these patients. Orofacial features in mucopolysaccharidosis may help pediatric dentists recognize this disorder and minimize the delay between the initial signs/symptoms and diagnosis of the disease. Future studies should focus on the longitudinal manifestations, expression, and severity of mucopolysaccharidosis-associated orofacial anomalies.