Rare GBA1 genotype associated with severe bone disease in Gaucher disease type 1

Introduction:Gaucher disease (GD) type 1 is a lysosomal disease characterised by hepatosplenomegaly, anemia,thrombocytopenia, bone changes, and bone marrow infiltration. The disease is caused by biallelic pathogenicvariants inGBA1which codes for glucocerebrosidase, an enzyme involved in the catabolic pathway of complexlipids.Aims:To report on the case of two sisters with GD type 1 who bear a genotype never reported in the literature.Case report:Patient 1 is a 47-year-old female diagnosed at 42 years of age with chronic lumbar pain, mildsplenomegaly, slightly reduced platelets and normal hemoglobin values, severe Bone Marrow Burden (BMB)score, high chitotriosidase activity, and low glucocerebrosidase. Patient 2 is a 50-year-old female, sister of pa-tient 1, who was diagnosed after familial screening. At 45 years of age, she had osteonecrosis of the left femurand a total hysterectomy because of uncontrollable bleeding. Atfirst evaluation, she had bone pain with a highBMB score, mild splenomegaly, normal hemoglobin, normal platelets count, elevated chitotriosidase activity,and low glucocerebrosidase activity. Both patients were found to be compound heterozygotes for thep.Glu388Lys and the p.Ser405Asn variants inGBA1.Conclusions:This is thefirst family with GD and this combination of variants which causes a phenotype re-markable for severe bone disease with no or mild hematological manifestations

Lysosomal diseases : overview on current diagnosis and treatment

Lysosomal diseases (LDs), also known as lysosomal storage diseases (LSDs), are a heterogeneous group of conditions caused by defects in lysosomal function. LDs may result from deficiency of lysosomal hydrolases, membrane-associated transporters or other non-enzymatic proteins. Interest in the LD field is growing each year, as more conditions are, or will soon be treatable. In this article, we review the diagnosis of LDs, from clinical suspicion and screening tests to the identification of enzyme or protein deficiencies and molecular genetic diagnosis. We also cover the treatment approaches that are currently available or in development, including hematopoietic stem cell transplantation, enzyme replacement therapy, small molecules, and gene therapy

Detecção de glicosilceramida em plasma de pacientes com doença de Gaucher

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Monitoring of phenylalanine levels in patients with phenylketonuria using dried blood spots : a comparison of two methods

Phenylketonuria (PKU) is caused by deficient activity of phenylalanine hydroxylase (PAH), responsible for the conversion of phenylalanine (Phe) to tyrosine (Tyr). Monitoring of patients with PKU requires the measurement of Phe in plasma using highperformance liquid chromatography (HPLC) or in dried blood spots (DBS) using different techniques to adjust treatment strategy. The objective of this study was to evaluate Phe levels in DBS measured by two different methods and compare them with Phe levels measured in plasma by HPLC. We analyzed 89 blood samples from 47 PKU patients by two different methods: fluorometric method developed in-house (method A) and the commercially available PerkinElmer® Neonatal Phenylalanine Kit (method B) and in plasma by HPLC. The mean Phe levels by method A, method B, and HPLC were 430.4±39.9μmol/L, 439.3±35.4μmol/L, and 442.2±41.6μmol/L, respectively. The correlation values between HPLC and methods A and B were 0.990 and 0.974, respectively (p<0.001 for both). Our data suggest that methods A and B are useful alternatives for monitoring Phe levels in patients with PKU, with method A being in closer agreement with the reference standard (HPLC)

Updated birth prevalence and relative frequency of mucopolysaccharidoses across Brazilian regions

The mucopolysaccharidoses (MPS) are a group of lysosomal storage disorders caused by 11 enzyme deficiencies, classified into seven types. Data on the birth prevalence of each MPS type are available for only a few countries, and the totality of cases may be underestimated. To determine the epidemiological profile of MPS in each Brazilian region, we analyzed data collected between 1982 and 2019 by a national reference laboratory and identified 1,652 patients. Using data between 1994 and 2018, the birth prevalence (by 100,000 live births) for MPS was 1.57. MPS II was the most common type of MPS in Brazil, and its birth prevalence was 0.48 (0.94 considering only male births). Regarding the number of cases per region, MPS II was the most frequent in the North and Center-West (followed by MPS VI), and also in the Southeast (followed by MPS I); MPS I and MPS II were the most common types in the South; and MPS VI was the most common in the Northeast (followed by MPS II). The differences observed in the relative frequencies of MPS types across Brazilian regions are likely linked to founder effect, endogamy, and consanguinity, but other factors may be present and need further investigation

Experience of the NPC Brazil network with a comprehensive program for the screening and diagnosis of Niemann-Pick disease type C

Niemann-Pick disease type C (NPC) is a lysosomal disorder caused by impaired cholesterol metabolism. Levels of lysosphingomyelin 509 (LysoSM509) have been shown elevated in dried blood spots (DBS) of NPC and acid sphingomyelinase deficiency patients. In this study, we report our experience using a two-tier approach (1st tier is the quantification of lysoSM509 by ultra-performance liquid chromatography tandem mass spectrometry followed by the 2nd tier with next-generation sequencing of the NPC1 and NPC2 genes). DBS samples from 450 suspected patients were received by the NPC Brazil network. Of these, 33 samples had elevated levels of lysoSM509, and in 25 of them, variants classified as pathogenic, likely pathogenic, or of unknown significance were identified in the NPC1 or NPC2 genes by next-generation sequencing. The quantification of lysoSM509 in DBS as a first-tier test for the diagnosis of NPC followed by molecular analysis of the NPC1 and NPC2 genes almost doubled the detection rate when compared to the performance of chitotriosidase activity as a first-tier biomarker, and it could likely be increased with the addition of a third tier with MLPA of the two genes involved. This strategy seems suitable for the neonatal screening (NBS) of NPC if this disease is eventually adopted by NBS programs