Gaucher disease: when molecular testing and clinical presentation disagree -the novel c.1226A>G(p.N370S)--RecNcil allele

Revisiting the diagnosis of Gaucher disease in a family with multiple GBA1 variants

Our ability to identify different variants in GBA1, the gene mutated in the lysosomal storage disorder Gaucher disease (GD), has greatly improved. We describe a multigenerational family with type 1 GD initially evaluated over three decades ago. Re-evaluating both the genotype and phenotype, we determined that one family member with genotype N370S/T369M (p.N409S/p.T408M), was likely erroneously diagnosed with GD. This case substantiates that GBA1 variant T369M, while mildly reducing glucocerebrosidase activity, does not result in GD. The observation has clinical relevance as cases with this genotype will increasingly be ascertained through screening programs in newborns and in movement disorder clinics.

Diagnosing neuronopathic Gaucher disease: New considerations and challenges in assigning Gaucher phenotypes

Gaucher disease (GD), resulting from biallelic mutations in the gene GBA1, is a monogenic recessively inherited Mendelian disorder with a wide range of phenotypic presentations. The more severe forms of the disease, acute neuronopathic GD (GD2) and chronic neuronopathic GD (GD3), also have a continuum of disease severity with an overlap in manifestations and limited genotype-phenotype correlation. In very young patients, assigning a definitive diagnosis can sometimes be challenging. Several recent studies highlight specific features of neuronopathic GD that may provide diagnostic clues. Distinguishing between the different GD types has important therapeutic implications. Currently there are limited treatment options specifically for neuronopathic GD due to the difficulty in delivering therapies across the blood-brain barrier. In this work, we present both classic and newly appreciated aspects of the Gaucher phenotype that can aid in discriminating between acute and chronic neuronopathic GD, and highlight the continuing therapeutic challenges.

Three mutations of adult type 1 Gaucher disease found in a Chinese patient: A case report

RATIONALE

Gaucher disease (GD), characterized by glucosylceramide accumulation in the macrophage-monocyte system, is caused by glucosidase b acid (GBA) gene mutations which lead to the deficiency of lysosomal enzyme glucocerebrosidase. The mutation spectrum of GBA in Chinese patients is quite different from those seen in Jewish and non-Jewish Caucasian patients. Thus, it is relatively hard to diagnose GD in Chinese.

PATIENT CONCERNS

A 24-year-old Chinese female with intermittent abdominal distension and progressive decrease in strength but without neurologic symptoms was initially referred for femoral head necrosis on the right feet. Laboratory examinations results indicated panhematopenia. Bone marrow aspiration smear and biopsy specimen found typical "wrinkled" Gaucher cells. Molecular-genetic testing of GBA gene revealed 3 mutations including R159W (c. 475 C > T), V1230G (c. 689T > G), and G241A (c. 721G > A).

DIAGNOSES

On the basis of these findings and clinical manifestations, the final diagnosis of type 1 GD was made.

INTERVENTIONS

Enzyme replacement therapy (ERT) with velaglucerase α was carried out after the diagnosis of type 1 GD.

OUTCOMES

The platelet and hemoglobin levels were restored by ERT.

LESSONS

To our knowledge, this is the first report of GD patient carrying 3 mutations in Chinese. These mutations in GBA in the present case imply a potential pool of patients with GD with this mutation in Chinese.

Alleles with more than one mutation can complicate genotype/phenotype studies in Mendelian disorders: Lessons from Gaucher disease

Autosomal resessive Mendelian disorders usually result from two inherited disease-causing mutations. However, this is not always the case. Focusing on Gaucher disease, which results from mutations in GBA1, we found that more comprehensive genotyping revealed important exceptions. For example, patients with uniparental disomy or new mutations do not inherit a mutation from each parent. Furthermore, we identified patients found to carry more than one GBA1 mutation on the same allele. It is essential to examine the entire GBA1 gene in order to establish an accurate genotype. Missing the second mutation can complicate genotype/phenotype studies and result in improper genetic counseling.

Neuropsychiatric characteristics of GBA-associated Parkinson disease

Mutations in GBA1 are a well-established risk factor for Parkinson disease (PD). GBA-associated PD (GBA-PD) may have a higher burden of nonmotor symptoms than idiopathic PD (IPD). We sought to characterize the relationship between GBA-PD and neuropsychiatric symptoms. Subjects were screened for common GBA1 mutations. GBA-PD (n=31) and non-carrier (IPD; n=55) scores were compared on the Unified Parkinson Disease Rating Scale (UPDRS), Montreal Cognitive Assessment (MoCA), Beck Depression Inventory (BDI), and the State-Trait Anxiety Index (STAI). In univariate comparisons, GBA-PD had a greater prevalence of depression (33.3%) versus IPD (13.2%) (p<0.05). In regression models controlling for age, sex, disease duration, motor disability, and MoCA score, GBA-PD had an increased odds of depression (OR 3.66, 95% CI 1.13-11.8) (p=0.03). Post-hoc analysis stratified by sex showed that, among men, GBA-PD had a higher burden of trait anxiety and depression than IPD; this finding was sustained in multivariate models. Among women, GBA-PD did not confer greater psychiatric morbidity than IPD. These results suggest that GBA1 mutations confer greater risk of neuropsychiatric morbidity in PD, and that sex may affect this association.

Cell surface associated glycohydrolases in normal and Gaucher disease fibroblasts

Gaucher disease (GD) is the most common lysosomal disorder and is caused by an inherited autosomal recessive deficiency in β-glucocerebrosidase. This enzyme, like other glycohydrolases involved in glycosphingolipid (GSL) metabolism, is present in both plasma membrane (PM) and intracellular fractions. We analyzed the activities of CBE-sensitive β-glucosidase (GBA1) and AMP-DNM-sensitive β-glucosidase (GBA2) in total cell lysates and PM of human fibroblast cell lines from control (normal) subjects and from patients with GD clinical types 1, 2, and 3. GBA1 activities in both total lysate and PM of GD fibroblasts were low, and their relative percentages were similar to those of control cells. In contrast, GBA2 activities were higher in GD cells than in control cells, and the degree of increase differed among the three GD types. The increase of GBA2 enzyme activity was correlated with increased expression of GBA2 protein as evaluated by QRT-PCR. Activities of β-galactosidase and β-hexosaminidase in PM were significantly higher for GD cells than for control cells and also showed significant differences among the three GD types, suggesting the occurrence of cross-talk among the enzymes involved in GSL metabolism. Our findings indicate that the profiles of glycohydrolase activities in PM may provide a valuable tool to refine the classification of GD into distinct clinical types.