Fernanda Bender

Genetic studies in a cluster of Mucopolysaccharidosis Type VI patients in Northeast Brazil

Mucopolysaccharidosis type VI (MPS VI, Maroteaux-Lamy syndrome) is a lysosomal storage disease caused by deficiency of arylsulphatase B. The incidence of MPS VI is very low, usually less than 1 case for every 1,000,000 newborns. In Northeast Brazil we identified in the county of Monte Santo (52,360 inhabitants) thirteen patients with MPS VI. The aim of this work was to identify the mutation(s) present in these patients and analyze intragenic SNPs to define possible haplotypes. The 13 MPS VI patients were found to be homozygous for the p.H178L mutation. All patients have the same haplotype for the intragenic SNPs. Based on current data, the prevalence of MPS VI in this region is estimated as 1:5,000 newborns. These results, together with pedigree analysis, strongly suggest a founder effect accounting for the high frequency of p.H178L mutation in this area. This reinforces the need of a comprehensive community genetics program for this area.

Oxidative stress and inflammation in mucopolysaccharidosis type IVA patients treated with enzyme replacement therapy

Mucopolysaccharidosis type IVA (MPS IVA) is an inborn error of glycosaminoglycan (GAG) catabolism due to the deficient activity of N-acetylgalactosamine-6-sulfate sulfatase that leads to accumulation of the keratan sulfate and chondroitin 6-sulfate in body fluids and in lysosomes. The pathophysiology of this lysosomal storage disorder is not completely understood. The aim of this study was to investigate oxidative stress parameters, pro-inflammatory cytokine and GAG levels in MPS IVA patients. We analyzed urine and blood samples from patients under ERT (n=17) and healthy age-matched controls (n=10-15). Patients presented a reduction of antioxidant defense levels, assessed by a decrease in glutathione content and by an increase in superoxide dismutase activity in erythrocytes. Concerning lipid and protein damage, it was verified increased urine isoprostanes and di-tyrosine levels and decreased plasma sulfhydryl groups in MPS IVA patients compared to controls. MPS IVA patients showed higher DNA damage than control group and this damage had an oxidative origin in both pyrimidine and purine bases. Interleukin 6 was increased in patients and presented an inverse correlation with GSH levels, showing a possible link between inflammation and oxidative stress in MPS IVA disease. The data presented suggest that pro-inflammatory and pro-oxidant states occur in MPS IVA patients even under ERT. Taking these results into account, supplementation of antioxidants in combination with ERT can be a tentative therapeutic approach with the purpose of improving the patients quality of life. To the best of our knowledge, this is the first study relating MPS IVA patients with oxidative stress.

Reliable detection of mucopolysacchariduria in dried-urine filter paper samples.

BACKGROUND The mucopolysaccharidoses (MPS) are inherited metabolic disorders with bone, joint, and visceral abnormalities, leading to multi-organ dysfunction and, sometimes, neurological manifestations. These diseases are caused by storage of glycosaminoglycans (GAGs) and other complex molecules in tissues, among other pathogenic mechanisms. Definitive diagnosis of the affected individual is mainly based on the identification of the specific enzyme deficiency. New therapies are available or are in development for these pathologies, and early diagnosis seems to be important for the therapy outcomes. Almost all MPS patients have increased levels of GAGs in urine being their evaluation usually the first step in the screening of these conditions. Test on urine may be challenging as transportation of liquid urine samples in appropriate conditions for long distances, especially across international borders, could be difficult. METHODS With the aim of overcoming the difficulties related to the use of liquid samples, we extended and validated previous studies about colorimetric determination of GAGs in dried-urine filter paper (DUFP) samples. RESULTS In the conditions we described, there are no differences in the concentration of GAGs between urine and DUFP samples. Untreated patients with MPS and normal controls were well discriminated using any of the samples. CONCLUSIONS Dried-urine filter paper is a suitable sample for the colorimetric quantitation of GAGs, and that its incorporation as an additional tool for screening of MPS should be considered by reference laboratories.

Investigation of newborns with abnormal results in a newborn screening program for four lysosomal storage diseases in Brazil

Lysosomal storage diseases (LSDs) are genetic disorders, clinically heterogeneous, mainly caused by defects in genes encoding lysosomal enzymes that degrade macromolecules. Several LSDs already have specific therapies that may improve clinical outcomes, especially if introduced early in life. With this aim, screening methods have been established and newborn screening (NBS) for some LSDs has been developed. Such programs should include additional procedures for the confirmation (or not) of the cases that had an abnormal result in the initial screening. We present here the methods and results of the additional investigation performed in four babies with positive initial screening results in a program of NBS for LSDs performed by a private laboratory in over 10,000 newborns in Brazil. The suspicion in these cases was of Mucopolysaccharidosis I - MPS I (in two babies), Pompe disease and Gaucher disease (one baby each). One case of pseudodeficiency for MPS I, 1 carrier for MPS I, 1 case of pseudodeficiency for Pompe disease and 1 carrier for Gaucher disease were identified. This report illustrates the challenges that may be encountered by NBS programs for LSDs, and the need of a comprehensive protocol for the rapid and precise investigation of the babies who have an abnormal screening result.

Elevation of glycosaminoglycans in the amniotic fluid of a fetus with mucopolysaccharidosis VII

The aim of this study was to quantify glycosaminoglycans (GAGs) in amniotic fluid (AF) from an MPS VII fetus compared with age‐matched fetuses obtained from normal pregnancies.

Enzyme Replacement Therapy With Elosulfase Alfa Decreases Storage of Glycosaminoglycan in White Blood Cells of Patients With Morquio A Syndrome

Mucopolysaccharidosis IVA (MPS IVA; Morquio A syndrome) is a lysosomal storage disorder caused by a deficient N-acetylgalactosamine-6-sulfate sulfatase activity, leading to cellular storage of undegraded keratan sulfate. Recently enzyme replacement therapy (ERT) was approved for MPS IVA, but some of ERT effects are still unknown. In the present study, we aimed to evaluate the efficacy of elosulfase alfa upon glycosaminoglycan (GAG) storage in peripheral blood white blood cells of patients with MPS IVA treated for 6 months, comparing samples from patients who received weekly infusions of enzyme (ERT-W) versus infusions every other week (ERT-EOW) versus placebo. A significant reduction in GAG storage was observed in both ERT-treated groups, with weekly ERT showing slightly better performance than ERT-EOW.