Gaucher disease in Colombia: mutation identification and comparison to other Hispanic populations

Genetic characterization of the Albanian Gaucher disease patient population

Gaucher disease (GD) is a recessive metabolic disorder caused by a deficiency of the GBA gene-encoded enzyme β-glucocerebrosidase. We characterized a cohort of 36 Albanian GD patients, 31 with GD type 1 and 5 affected by GD types 2, 3, and an intermediate GD phenotype between type 2 and type 3. Of the 12 different GBA alleles that we detected, the most frequently observed was p.Asn409Ser, followed by p.[Asp448His;His294Gln]. The prevalence of the p.Leu483Pro allele was approximately 10-fold lower than reported in other populations. We identified a novel pathogenic missense variant (c.1129G>A; p.Ala377Thr). All five of our non-type 1 patients had genotypes consisting of the p.[Asp448His;His294Gln] allele in combination with another severe GBA allele. The median Lyso-Gb1 level of treated patients carrying the p.[Asp448His;His294Gln] and no p.Asn409Ser allele was significantly higher than that of treated individuals homozygous or compound heterozygous for the p.Asn409Ser allele. In conclusion, the most important distinguishing features of the Albanian GD patient population are the underrepresentation of the p.Leu483Pro allele and an unusually high number of p.[Asp448His;His294Gln] alleles originating from a common Balkan founder event. The presence of at least one p.Asn409Ser allele is associated with mild disease and low Lyso-Gb1 biomarker levels, while compound heterozygosity involving p.[Asp448His;His294Gln] and no p.Asn409Ser entails severe phenotypes and high Lyso-Gb1 levels.

A perspective on research, diagnosis, and management of lysosomal storage disorders in Colombia

Lysosomal storage diseases (LSDs) are a group of about 50 inborn errors of metabolism characterized by the lysosomal accumulation of partially or non-degraded molecules due to mutations in proteins involved in the degradation of macromolecules, transport, lysosomal biogenesis or modulators of lysosomal environment. Significant advances have been achieved in the diagnosis, management, and treatment of LSDs patients. In terms of approved therapies, these include enzyme replacement therapy (ERT), substrate reduction therapy, hematopoietic stem cell transplantation, and pharmacological chaperone therapy. In this review, we summarize the Colombian experience in LSDs thorough the evidence published. We identified 113 articles published between 1995 and 2019 that included Colombian researchers or physicians, and which were mainly focused in Mucopolysaccharidoses, Pompe disease, Gaucher disease, Fabry disease, and Tay-Sachs and Sandhoff diseases. Most of these articles focused on basic research, clinical cases, and mutation reports. Noteworthy, implementation of the enzyme assay in dried blood samples, led to a 5-fold increase in the identification of LSD patients, suggesting that these disorders still remain undiagnosed in the country. We consider that the information presented in this review will contribute to the knowledge of a broad spectrum of LSDs in Colombia and will also contribute to the development of public policies and the identification of research opportunities.

The distribution and risk effect of GBA variants in a large cohort of PD patients from Colombia and Peru

BACKGROUND

Mutations in the glucocerebrosidase (GBA) gene are an important risk factor for Parkinson's disease (PD). However, most GBA genetic studies in PD have been performed in patients of European origin and very few data are available in other populations.

METHODS

We sequenced the entire GBA coding region in 602 PD patients and 319 controls from Colombia and Peru enrolled as part of the Latin American Research Consortium on the Genetics of Parkinson's disease (LARGE-PD).

RESULTS

We observed a significantly higher proportion of GBA mutation carriers in patients compared to healthy controls (5.5% vs 1.6%; OR = 4.3, p = 0.004). Interestingly, the frequency of mutations in Colombian patients (9.9%) was more than two-fold greater than in Peruvian patients (4.2%) and other European-derived populations reported in the literature (4-5%). This was primarily due to the presence of a population-specific mutation (p.K198E) found only in the Colombian cohort. We also observed that the age at onset was significantly earlier in GBA carriers when compared to non-carriers (47.1 ± 14.2 y vs. 55.9 ± 14.2 y; p = 0.0004).

CONCLUSION

These findings suggest that GBA mutations are strongly associated with PD risk and earlier age at onset in Peru and Colombia. The high frequency of GBA carriers among Colombian PD patients (∼10%) makes this population especially well-suited for novel therapeutic approaches that target GBA-related PD.

Gaucher disease in Syrian children: common mutations identification, and clinical futures

BACKGROUND AND OBJECTIVES

Gaucher disease (GD) is caused by the deficiency of glucosidase beta acid (GBA). Three clinical forms of GD are available. Some mutations in the GBA gene have a high frequency in spe.cific populations. The aim of this study was to analyze the characteristics of phenotypes and genotypes of GD in Syrian pediatric patients and assess whether a genotype-phenotype relationship could be helpful in treatment decision-making.

DESIGN AND SETTINGS

A cross-sectional clinical genetic study of 19 Syrian children admitted to Children's Hospital, Damascus University.

PATIENTS AND METHODS

Nineteen Syrian children with GD were enrolled in the study; DNA was extracted from peripheral blood leukocytes. The GBA gene was amplified by polymerase chain reaction, and the 9 most common mutations were studied using a Gaucher Disease Strip Assay (ViennaLab Diagnostics GmbH, Vienna, Austria).

RESULTS

The majority of children had an early age of onset. A total of17 patients presented severe hematological and skeletal complications. Neurological involvement was encountered in 2 patients. Twelve patients (63, 2%) were homozygous for the L444P mutation, 1 patient (5.3%) was homozygous for the N370S mutation, and 1 patient (5.3%) was heterozygous for the N370S mutation. Five patients (26.3%) had unknown mutations.

CONCLUSION

L444P/L444P was the most common genotype in the studied patients. GD3 with severe visceral presentation in childhood was the dominant phenotype; N370S was found in the heterozygote state in 1 case and in the homozygote state in 1 case. This phenotype and genotype pattern is encountered in the Middle East. There was no genotype-phenotype correlation.

A phase 2 study of eliglustat tartrate (Genz-112638), an oral substrate reduction therapy for Gaucher disease type 1

Eliglustat tartrate (Genz-112638), a specific inhibitor of glucosylceramide synthase, is under development as an oral substrate reduction therapy for Gaucher disease type 1 (GD1). A multinational, open-label, single-arm phase 2 study of 26 GD1 patients (16 female, 10 male; mean age, 34 years) evaluated the efficacy, safety, and pharmacokinetics of eliglustat tartrate administered twice daily by mouth at 50- or 100-mg doses based on plasma drug concentrations. Entry criteria required splenomegaly with thrombocytopenia and/or anemia. The composite primary efficacy end point required improvement after 52 weeks in at least 2 of these 3 disease manifestations and was met by 77% (95% confidence interval [CI] = 58%-89%) of all patients and 91% (95% CI = 72%-98%) of the 22 patients completing 52 weeks. Statistically significant improvements occurred in mean hemoglobin level (1.62 g/dL; 95% CI =1.05-2.18 g/dL), platelet count (40.3%; 95% CI = 23.7-57.0 g/dL), spleen volume (-38.5%; 95% CI = -43.5%--33.5%), liver volume (-17.0%; 95% CI = -21.6%-12.3%), and lumbar spine bone mineral density (0.31 Z-score; 95% CI = 0.09-0.53). Elevated biomarkers (chitotriosidase; chemokine CCL18; angiotensin-converting enzyme; tartrate-resistant acid phosphatase) decreased by 35% to 50%. Plasma glucosylceramide and ganglioside GM3 normalized. Eliglustat tartrate was well tolerated: 7 mild, transient adverse events in 6 patients were considered treatment-related. Individual pharmacokinetics varied; mean time to maximal observed concentration was 2.3 hours and mean half-life was 6.8 hours. Eliglustat tartrate appears to be a promising oral treatment for GD1.

An evolutionary and structure-based docking model for glucocerebrosidase-saposin C and glucocerebrosidase-substrate interactions - relevance for Gaucher disease

Gaucher disease, the most prevalent lysosomal storage disorder, is principally caused by malfunction of the lysosomal enzyme glucocerebrosidase (GBA), a 497-amino acid membrane glycoprotein that catalyzes the hydrolysis of glucosylceramide to ceramide and glucose in the presence of an essential 84-residue activator peptide named saposin C (SapC). Knowledge of the GBA structure, a typical (beta/alpha)(8) TIM barrel, explains the effect of few mutations, directly affecting or located near the catalytic site. To identify new regions crucial for proper GBA functionality, we analyzed the interactions of the enzyme with a second (substrate) and a third (cofactor) partner. We build 3D docking models of the GBA-SapC and the GBA-ceramide interactions, by means of methodologies that integrate both evolutive and structural information. The GBA-SapC docking model confirm the implication of three spatially closed regions of the GBA surface (TIM barrel-helix 6 and helix 7, and the Ig-like domain) in binding the SapC molecule. This model provides new basis to understand the pathogenicity of several mutations, such as the prevalent Leu444Pro, and the additive effect of Glu326Lys in the double mutant Glu326Lys-Leu444Pro. Overall, 39 positions in which amino acid changes are known to cause Gaucher disease were localized in the GBA regions identified in this work. Our model is discussed in relation to the phenotype (pathogenic effect) of these mutations, as well as to the enzymatic activity of the recombinant proteins when available. Both data fully correlates with the proposed model, which will provide a new tool to better understand Gaucher disease and to design new therapy strategies.

Detection of 12 new mutations in Gaucher disease Brazilian patients

Gaucher disease is the most frequent lysosome storage disease and presents an autosomal recessive mode of inheritance. It is caused by mutations at the GBA gene leading to deficient activity of the glucocerebrosidase enzyme. This report describes 12 new mutations [c.38A>G (K-27R), c.220G>A (G35S), c.448G>A (E111K), IVS4+1G>A, c.746C>T (A210V), c.776A>G (Y220C), c.793delC (Q226_fs4X), c.1102C>T (R329C), c.1300C>T (R395C), c.1309G>A (V398I), c.1324-1326delATT (delI403) and c.1583T>C (I489T)] and 4 novel silent alterations [c.342C>T (F75), c.528C>T (D137), c.1011C>T (D298) and c.1092G>A (G325)] detected among 40 unrelated Brazilian type 1 Gaucher disease patients by a combination of RFLP, dHPLC and DNA sequencing procedures. The R329C mutation, previously described in a Parkinson's disease patient (A. Lwin, E. Orvisky, O. Goker-Alpan, M.E. LaMarca, E. Sidransky. Glucocerebrosidase mutations in subjects with Parkinsonism. Mol. Genet. Metab. 81 (2004) 70-73), is described here for the first time in a Gaucher disease patient. Several genotype-phenotype correlations could be established, contributing significantly to the panel of reported mutations and conferring predictive value to their detection.