Sex distribution and classification of GBA1 variants in an Italian cohort of Parkinson's disease patients analyzed over the last seventeen years

INTRODUCTION

Heterozygous GBA1 variants are among the most frequent genetic risk factors for Parkinson's disease (PD). Male sex is a risk factor in the development of PD but the sex prevalence of GBA1 carriers in PD patients remains debatable. Molecular analysis of the GBA1 gene is complicated by the presence of a highly homologous pseudogene GBAP1.

METHOD

Starting from 2006, we screened GBA1 gene in a large cohort of 1762 PD patients through different techniques developed over the years. Identified variants were classified employing the GBA1-PD browser and compared on the basis of frequency and sex distribution.

RESULTS

Within a group of 684 patients (40.2% Males -M-) analyzed with RFLP technique looking for the two most common GBA1 mutations L444P and N370S, 29 resulted positive (4.23%). Out of 537 patients (67.4% M) analyzed with PCR that amplifies the portion of the gene between exon 8 and exon 11, we found 53 positive carriers (9.87%). Out of 424 patients (60.8% M) analyzed with NGS custom gene panel with allele-specific PCR, 50 resulted positive (11.79%). Since 2022, we also analyzed 117 patients (56.4% M) with long PCR sequenced with NGS, identifying 17 positive samples (14.52%).

CONCLUSION

In our study, we highlight that screening the entire GBA1 gene with specific techniques increases the diagnostic rate. Regarding variants distribution, males have shown a higher frequency of the severe variants and complex alleles, whereas mild variants are equally distributed in both sexes and risk variants are more frequent in females especially the T369 M.

Exploring the link between GBA1 mutations and Dementia with Lewy bodies, A mini-review

IMPORTANCE

Dementia with Lewy bodies (DLB) is a neurodegenerative disease linked to abnormal accumulation of phosphorylated α-synuclein. GBA1 is the gene encoding the lysosomal enzyme glucocerebrosidase (GCase), whose mutations are a risk factor of DLB.

OBJECTIVE

To report all available data exploring the association between GBA1 mutations and DLB.

EVIDENCE REVIEW

All publications focused on GCase and DLB in humans between 2003 and 2022 were identified on PubMed, Cochrane and ClinicalTrials.gov.

FINDINGS

29 studies were included and confirmed the strong association between GBA1 mutations and DLB (Odds Ratio [OR]: 8.28). GBA1 mutation carriers presented a more malignant phenotype, with earlier symptom onset, more severe motor and cognitive dysfunctions, more visual hallucinations and rapid eye movement sleep disorder. GBA1 mutations were associated with "purer" neuropathological DLB. No therapeutic recommendations exist and clinical trials targeting GCase are just starting in DLB patients.

CONCLUSIONS AND RELEVANCE

This review reports a link between GBA1 mutations and the DLB phenotype with limited evidence due to the small number of studies.

Establishment and Phenotypic Analysis of the Novel Gaucher Disease Mouse Model With the Partially Humanized Gba1 Gene and F213I Mutation

Gaucher disease (GD) is an autosomal recessive lysosomal storage disorder caused by mutations in the GBA1 gene, which produces the glucocerebrosidase (GCase) protein. There are more than 500 mutations reported in GBA1, among which L444P (p.Leu444Pro) and F213I (p.Phe213Ile) are the most common in the Chinese population, while the function of F213I mutation remains elusive. This study aims to establish the GD mouse model of partially humanized Gba1 gene with F213I mutation. In vitro GCase activity assays showed that the product of partially humanized Gba1 gene, in which the mouse exons 5-7 were replace by the corresponding human exons, displayed similar activity with the wild-type mouse Gba1, while the F213I mutation in the humanized Gba1 led to significant decrease in enzyme activity. ES cell targeting was used to establish the mice expressing the partially humanized Gba1-F213I. Gba1^F213I/+ mice did not show obviously abnormal phenotypes, but homozygous Gba1^F213I/F213I mice died within 24 h after birth, whose epidermal stratum corneum were abnormal from the wild-type. The GCase activity in Gba1^F213I/F213I mice greatly decreased. In conclusion, our results showed that the partially humanized GD mouse model with the F213I mutation was developed and homozygous F213I mutation is lethal for newborn mice.

Mini review - The role of Glucocerebrosidase and Progranulin as possible targets in the treatment of Parkinson's disease

As per recent reports, there is an association between glucocerebrosidase (Gcase) enzyme and Parkinson's disease (PD). In addition, certain mutations in the Gcase gene (GBA) and the progranulin (PGRN) gene are found to be linked with the imbalance in the levels of Gcase enzyme. This imbalance or decrease or impairment in Gcase activity can lead to Gaucher disease, frontotemporal lobar degeneration (FTLD), dementia, etc. Recent evidences suggest that the drugs used to treat these diseases can be used for PD. The present review has focused on the therapeutic approaches used for diseases linked with Gcase enzyme, which can be used for PD. The review also considered possible target specific novel strategies, which may help to meet the unmet needs in the treatment of PD.

Gaucher disease: single gene molecular characterization of one-hundred Indian patients reveals novel variants and the most prevalent mutation

Background

Gaucher disease is a rare pan-ethnic, lysosomal storage disorder resulting due to beta-Glucosidase (GBA1) gene defect. This leads to the glucocerebrosidase enzyme deficiency and an increased accumulation of undegraded glycolipid glucocerebroside inside the cells’ lysosomes. To date, nearly 460 mutations have been described in the GBA1 gene. With the aim to determine mutations spectrum and molecular pathology of Gaucher disease in India, the present study investigated one hundred unrelated patients (age range: 1 day to 31 years) having splenomegaly, with or without hepatomegaly, cytopenia and bone abnormality in some of the patients.

Methods

The biochemical investigation for the plasma chitotriosidase enzyme activity and β-Glucosidase enzyme activity confirmed the Gaucher disease. The mutations were identified by screening the patients’ whole GBA gene coding region using bidirectional Sanger sequencing.

Results

The biochemical analysis revealed a significant reduction in the β-Glucosidase activity in all patients. Sanger sequencing established 71 patients with homozygous mutation and 22 patients with compound heterozygous mutation in GBA1 gene. Lack of identification of mutations in three patients suggests the possibility of either large deletion/duplication or deep intronic variations in the GBA1 gene. In four cases, where the proband died due to confirmed Gaucher disease, the parents were found to be a carrier. Overall, the study identified 33 mutations in 100 patients that also covers four missense mutations (p.Ser136Leu, p.Leu279Val, p.Gly383Asp, p.Gly399Arg) not previously reported in Gaucher disease patients. The mutation p.Leu483Pro was identified as the most commonly occurring Gaucher disease mutation in the study (62% patients). The second common mutations identified were p.Arg535Cys (7% patients) and RecNcil (7% patients). Another complex mutation Complex C was identified in a compound heterozygous status (3% patients). The homology modeling of the novel mutations suggested the destabilization of the GBA protein structure due to conformational changes.

Conclusions

The study reports four novel and 29 known mutations identified in the GBA1 gene in one-hundred Gaucher patients. The given study establishes p.Leu483Pro as the most prevalent mutation in the Indian patients with type 1 Gaucher disease that provide new insight into the molecular basis of Gaucher Disease in India.

Electronic supplementary material

The online version of this article (10.1186/s12881-019-0759-1) contains supplementary material, which is available to authorized users.

Cerebrospinal fluid β-glucocerebrosidase activity is reduced in parkinson's disease patients

BACKGROUND

Reduced β-glucocerebrosidase activity was observed in postmortem brains of both GBA1 mutation carrier and noncarrier Parkinson's disease patients, suggesting that lower β-glucocerebrosidase activity is a key feature in the pathogenesis of PD. The objectives of this study were to confirm whether there is reduced β-glucocerebrosidase activity in the CSF of GBA1 mutation carrier and noncarrier PD patients and verify if other lysosomal enzymes show altered activity in the CSF.

METHODS

CSF β-glucocerebrosidase, cathepsin D, and β-hexosaminidase activities were measured in 79 PD and 61 healthy controls from the BioFIND cohort. The whole GBA1 gene was sequenced.

RESULTS

Enzyme activities were normalized according to CSF protein content (specific activity). β-glucocerebrosidase specific activity was significantly decreased in PD versus controls (-28%, P < 0.001). GBA1 mutations were found in 10 of 79 PD patients (12.7%) and 3 of 61 controls (4.9%). GBA1 mutation carrier PD patients showed significantly lower β-glucocerebrosidase specific activity versus noncarriers. β-glucocerebrosidase specific activity was also decreased in noncarrier PD patients versus controls (-25%, P < 0.001). Cathepsin D specific activity was lower in PD versus controls (-21%, P < 0.001). β-Hexosaminidase showed a similar trend. β-Glucocerebrosidase specific activity fairly discriminated PD from controls (area under the curve, 0.72; sensitivity, 0.67; specificity, 0.77). A combination of β-glucocerebrosidase, cathepsin D, and β-hexosaminidase improved diagnostic accuracy (area under the curve, 0.77; sensitivity, 0.71; specificity, 0.85). Lower β-glucocerebrosidase and β-hexosaminidase specific activities were associated with worse cognitive performance.

CONCLUSIONS

CSF β-glucocerebrosidase activity is reduced in PD patients independent of their GBA1 mutation carrier status. Cathepsin D and β-hexosaminidase were also decreased. The possible link between altered CSF lysosomal enzyme activities and cognitive decline deserves further investigation. © 2017 International Parkinson and Movement Disorder Society.

A Review of Gaucher Disease Pathophysiology, Clinical Presentation and Treatments

Gaucher disease (GD, ORPHA355) is a rare, autosomal recessive genetic disorder. It is caused by a deficiency of the lysosomal enzyme, glucocerebrosidase, which leads to an accumulation of its substrate, glucosylceramide, in macrophages. In the general population, its incidence is approximately 1/40,000 to 1/60,000 births, rising to 1/800 in Ashkenazi Jews. The main cause of the cytopenia, splenomegaly, hepatomegaly, and bone lesions associated with the disease is considered to be the infiltration of the bone marrow, spleen, and liver by Gaucher cells. Type-1 Gaucher disease, which affects the majority of patients (90% in Europe and USA, but less in other regions), is characterized by effects on the viscera, whereas types 2 and 3 are also associated with neurological impairment, either severe in type 2 or variable in type 3. A diagnosis of GD can be confirmed by demonstrating the deficiency of acid glucocerebrosidase activity in leukocytes. Mutations in the GBA1 gene should be identified as they may be of prognostic value in some cases. Patients with type-1 GD-but also carriers of GBA1 mutation-have been found to be predisposed to developing Parkinson's disease, and the risk of neoplasia associated with the disease is still subject to discussion. Disease-specific treatment consists of intravenous enzyme replacement therapy (ERT) using one of the currently available molecules (imiglucerase, velaglucerase, or taliglucerase). Orally administered inhibitors of glucosylceramide biosynthesis can also be used (miglustat or eliglustat).