UPR activation and CHOP mediated induction of GBA1 transcription in Gaucher disease.

Chronic presence of mutant, misfolded proteins in the endoplasmic reticulum (ER) initiates ER stress and induces the Unfolded Protein Response (UPR). In Gaucher disease (GD), resulting from mutations in the GBA1 gene, encoding lysosomal acid ß-glucocerebrosidase (GCase), a certain fraction of the mutant variants is retained in the ER and activates the UPR. We have previously shown UPR activation in GD derived fibroblasts, in fibroblasts that derived from carriers of GD mutations and in Drosophila models of carriers of GD mutations. In the present work we extended our studies to include a large collection of fibroblasts, EBV-transformed B-cells and white blood cells (WBCs) that derived from GD patients. The results showed UPR activation in all tested cells. They also indicated that transcription of the GBA1 gene is upregulated through activation of the UPR-induced CHOP transcription factor. Transcription of the MAN2B gene, encoding alpha-mannosidase and of the ACP gene, encoding acid phosphatase was also elevated presumably through CHOP activation. Our results highlight the existence of chronic stress in GD derived cells due to the presence of ER-retained mutant GCase, which leads to upregulation of GBA1 expression.

Proof-of-principle rapid noninvasive prenatal diagnosis of autosomal recessive founder mutations.

BACKGROUND: Noninvasive prenatal testing can be used to accurately detect chromosomal aneuploidies in circulating fetal DNA; however, the necessity of parental haplotype construction is a primary drawback to noninvasive prenatal diagnosis (NIPD) of monogenic disease. Family-specific haplotype assembly is essential for accurate diagnosis of minuscule amounts of circulating cell-free fetal DNA; however, current haplotyping techniques are too time-consuming and laborious to be carried out within the limited time constraints of prenatal testing, hampering practical application of NIPD in the clinic. Here, we have addressed this pitfall and devised a universal strategy for rapid NIPD of a prevalent mutation in the Ashkenazi Jewish (AJ) population. METHODS: Pregnant AJ couples, carrying mutation(s) in GBA, which encodes acid ß-glucosidase, were recruited at the SZMC Gaucher Clinic. Targeted next-generation sequencing of GBA-flanking SNPs was performed on peripheral blood samples from each couple, relevant mutation carrier family members, and unrelated individuals who are homozygotes for an AJ founder mutation. Allele-specific haplotypes were constructed based on linkage, and a consensus Gaucher disease-associated founder mutation-flanking haplotype was fine mapped. Together, these haplotypes were used for NIPD. All test results were validated by conventional prenatal or postnatal diagnostic methods. RESULTS: Ten parental alleles in eight unrelated fetuses were diagnosed successfully based on the noninvasive method developed in this study. The consensus mutation-flanking haplotype aided diagnosis for 6 of 9 founder mutation alleles. CONCLUSIONS: The founder NIPD method developed and described here is rapid, economical, and readily adaptable for prenatal testing of prevalent autosomal recessive disease-causing mutations in an assortment of worldwide populations. FUNDING: SZMC, Protalix Biotherapeutics Inc., and Centogene AG.

Molecular aspects of osteopathy in type 1 Gaucher disease: correlation between genetics and bone density.

Bone-related complications in Gaucher disease are considered to be poorly responsive to specific enzyme replacement therapy. Polymorphisms of candidate genes associated with low bone density were investigated to see whether they are correlated with bone mineral density (BMD) and bone involvement in Gaucher disease. Genotyping for polymorphisms in candidate genes (interleukins 1alpha and 1beta, interleukin-1 receptor antagonist; cytochrome P450; collagen 1A1; low-density Lipoprotein Receptor; bone morphogenic protein 4; vitamin D receptor; and estrogen receptor 2beta) were performed using standard methodologies. BMD was measured by dual energy X-ray absorptiometry (DXA). One hundred and ninety-four patients and 100 controls were genotyped for the above polymorphisms. Thirteen haplotypes were obtained, with several correlations with BMD in patients; also, a haplotype (T889-T3954-C511-240VNTR of IL1) was significantly correlated with T-scores and Z-score for femur neck and lumbar spine (p = 0.01) in patients. Haplotypes of bone-specific candidate genes associated with BMD may predict severity of these features in Gaucher disease.

The 1604A (R496H) mutation in Gaucher disease: genotype/phenotype correlation.

Gaucher disease is the most common sphingolipid storage disease but genotype only broadly predicts phenotype. The 1604G-->A (1604A;R496H) mutation has been described as having a low incidence among Ashkenazi Jews. The purpose of this study was to ascertain phenotypic expression and prevalence of this mutation among patients with Gaucher disease and among healthy Ashkenazi Jews. Patients in two Gaucher clinics (in the United States and Israel) and from an international Gaucher registry were assessed for frequency and phenotype expression; 200 healthy Ashkenazi Jews were screened as well. Molecular analysis was performed by standard methods. In the Gaucher clinic with mostly Jewish patients, the gene frequency was 1.68% compared with 0.38% in the international registry with mostly non-Jewish patients. Among Ashkenazi Jewish controls, no alleles with 1604A were identified. There was a marked overrepresentation of severe alleles in patients carrying the 1604A mutation, suggesting that many patients who are compound heterozygotes for 1604A are not diagnosed as having Gaucher disease because their disease is presumably so mild as to evade detection. In view of its rarity and mild expression, the inclusion of the 1604A mutation in the standard kit for screening for Gaucher disease is unnecessary.