Increased Rate of Sporadic and Recurrent Rare Genic Copy Number Variants in Parkinson's Disease Among Ashkenazi Jews

To date, only one genome-wide study has assessed the contribution of copy number variants (CNVs) to Parkinson's disease (PD). We conducted a genome-wide scan for CNVs in a case–control dataset of Ashkenazi Jewish (AJ) origin (268 PD cases and 178 controls). Using high-confidence CNVs, we examined the global genome wide burden of large (≥100 kb) and rare (≤1% in the dataset) CNVs between cases and controls. A total of 986 such CNVs were observed in our dataset of 432 subjects. Overall global burden analyses did not reveal significant differences between cases and controls in CNV rate, distribution of deletions or duplications or number of genes affected by CNVs. Overall deletions (total CNV size and ≥2× frequency) were found 1.4 times more often in cases than in controls (P = 0.019). The large CNVs (≥500 kb) were also significantly associated with PD (P = 0.046, 1.24-fold higher in cases than in controls). Global burden was elevated for rare CNV regions. Specifically, for OVOS2 on Chr12p11.21, CNVs were observed only in PD cases (n = 7) but not in controls (P = 0.028) and this was experimentally validated. A total of 81 PD cases carried a rare genic CNV that was absent in controls. Ingenuity pathway analysis (IPA) identified ATXN3, FBXW7, CHCHD3, HSF1, KLC1, and MBD3 in the same disease pathway with known PD genes.

Genetic analysis of the FUS/TLS gene in essential tremor

BACKGROUND AND PURPOSE

Although essential tremor (ET) has a genetic basis, specific genes have not been identified. Recently, in a large ET family (FET1) from Quebec, a non-sense mutation (p.Q290X) in the amyotrophic lateral sclerosis (ALS) gene fused in sarcoma/translated in liposarcoma (FUS/TLS) was identified by exome sequencing. No confirmatory studies have been published.

METHODS

Two-hundred and fifty-nine ET cases and 262 controls were enrolled in a study at Columbia University. We performed a comprehensive analysis of the FUS/TLS gene by sequencing all exons in a subsample of 116 ET cases with early-onset (≤40 years) ET. We evaluated an association between ET and SNPs in the FUS/TLS gene by genotyping four haplotype tagging SNPs in all 259 ET cases and 262 controls. Additionally, seven variants associated with ALS, two variants of unknown pathogenicity detected in ALS cases, eight mis-sense variants predicted to be damaging, and six rare variants were genotyped in these 259 ET cases and 262 controls.

RESULTS

FUS/TLS mutations previously reported in ALS, the FET1 family, or novel mutations were not found in any of the 116 early-onset ET cases. In the case-control analyses, although the power of the performed associations was limited, no significant association between tagging SNPs in FUS/TLS and ET was observed, and none of the analyzed SNPs showed evidence of association with ET.

CONCLUSION

Our study suggests that pathogenic mutations in FUS/TLS are rare in a sample of early-onset ET cases in North America. We did not find evidence that the FUS/TLS gene is a risk factor for ET.

Cognitive performance of GBA mutation carriers with early-onset PD: the CORE-PD study

OBJECTIVE

To assess the cognitive phenotype of glucocerebrosidase (GBA) mutation carriers with early-onset Parkinson disease (PD).

METHODS

We administered a neuropsychological battery and the University of Pennsylvania Smell Identification Test (UPSIT) to participants in the CORE-PD study who were tested for mutations in PARKIN, LRRK2, and GBA. Participants included 33 GBA mutation carriers and 60 noncarriers of any genetic mutation. Primary analyses were performed on 26 GBA heterozygous mutation carriers without additional mutations and 39 age- and PD duration-matched noncarriers. Five cognitive domains, psychomotor speed, attention, memory, visuospatial function, and executive function, were created from transformed z scores of individual neuropsychological tests. Clinical diagnoses (normal, mild cognitive impairment [MCI], dementia) were assigned blind to genotype based on neuropsychological performance and functional impairment as assessed by the Clinical Dementia Rating (CDR) score. The association between GBA mutation status and neuropsychological performance, CDR, and clinical diagnoses was assessed.

RESULTS

Demographics, UPSIT, and Unified Parkinson's Disease Rating Scale-III performance did not differ between GBA carriers and noncarriers. GBA mutation carriers performed more poorly than noncarriers on the Mini-Mental State Examination (p = 0.035), and on the memory (p = 0.017) and visuospatial (p = 0.028) domains. The most prominent differences were observed in nonverbal memory performance (p < 0.001). Carriers were more likely to receive scores of 0.5 or higher on the CDR (p < 0.001), and a clinical diagnosis of either MCI or dementia (p = 0.004).

CONCLUSION

GBA mutation status may be an independent risk factor for cognitive impairment in patients with PD.

Olfaction in Parkin heterozygotes and compound heterozygotes: the CORE-PD study

BACKGROUND

While Parkinson disease (PD) is consistently associated with impaired olfaction, one study reported better olfaction among Parkin mutation carriers than noncarriers. Whether olfaction differs between Parkin mutation heterozygotes and carriers of 2 Parkin mutations (compound heterozygotes) is unknown.

OBJECTIVE

To assess the relationship between Parkin genotype and olfaction in PD probands and their unaffected relatives.

METHODS

We administered the University of Pennsylvania Smell Identification Test (UPSIT) to 44 probands in the Consortium on Risk for Early-Onset Parkinson Disease study with PD onset ≤50 years (10 Parkin mutation heterozygotes, 9 compound heterozygotes, 25 noncarriers) and 80 of their family members (18 heterozygotes, 2 compound heterozygotes, 60 noncarriers). In the probands, linear regression was used to assess the association between UPSIT score (outcome) and Parkin genotype (predictor), adjusting for covariates. Among family members without PD, we compared UPSIT performance in heterozygotes vs noncarriers using generalized estimating equations, adjusting for family membership, age, gender, and smoking.

RESULTS

Among probands with PD, compound heterozygotes had higher UPSIT scores (31.9) than heterozygotes (20.1) or noncarriers (19.9) (p < 0.001). These differences persisted after adjustment for age, gender, disease duration, and smoking. Among relatives without PD, UPSIT performance was similar in heterozygotes (32.5) vs noncarriers (32.4), and better than in heterozygotes with PD (p = 0.001).

CONCLUSION

Olfaction is significantly reduced among Parkin mutation heterozygotes with PD but not among their heterozygous relatives without PD. Compound heterozygotes with PD have olfaction within the normal range. Further research is required to assess whether these findings reflect different neuropathology in Parkin mutation heterozygotes and compound heterozygotes.

Transduction of hematopoietic stem cells with a retroviral vector expressing the neomycin phosphotransferase gene

Transduction of stem cells with a marking gene holds promise to determine if tissue repair or regeneration is derived from the adult hematopoietic stem cell and if relapse of an autoimmune disease should occur whether relapse arises from the stem cell compartment or from lymphocytes surviving the conditioning regimen. New safety concerns about gene-modified stem cell would entail new safety testing such as documentation of the insertional site prior to release.

The high proliferative potential-quiescent (HPP-Q) cell assay allows an optimized evaluation of gene transfer efficiency into primitive hematopoietic stem/progenitor cells

Various protocols have been described to optimize gene transfer into hematopoietic cells. However, most of these methods do not specify whether they are associated with an improved transduction of the more primitive stem/progenitor cells, the best candidates for long-term engraftment. The majority of these primitive cells remains in quiescence because of the negative control of TGF-beta1, effective on these cells at low concentrations (10 pg/ml). In this study, CD34- cells were activated by a 10 h pretreatment with anti-TGF-beta1 followed by four successive retroviral supernatant incubations of 6 h each. After 12 h (two incubations), a significant increase in TGF-beta1 mRNA in CD34+ cells was observed. We wondered whether neo-synthesized autocrine TGF-beta1 could induce reversion to quiescence of the more primitive CD34+ cells transduced after one cell cycle. This would prevent their subsequent detection in a classic clonal assay. Using the HPP-Q assay comparing a rapid mixed colony assay with or without anti-TGF-beta1, we indeed observed, that in clonal growth conditions the more primitive transduced cells were activated and detectable only with anti-TGF-beta1. Therefore, this assay represents not only a rapid means to detect quiescent multipotent stem/progenitor cells but also a necessary step for the detection of the more primitive transduced cells which have returned to quiescence after retroviral induction of TGF-beta1 secretion.

Release from quiescence of primitive human hematopoietic stem/progenitor cells by blocking their cell-surface TGF-beta type II receptor in a short-term in vitro assay

Genetic alterations of the signaling cascade of transforming growth factor-beta (TGF-beta) are often associated with neoplastic transformation of primitive cells. This demonstrates the key role for this pleiotropic factor in the control of quiescence and cell proliferation in vivo. In the high proliferative potential-quiescent cell (HPP-Q) in vitro assay, the use of TGF-beta1 blocking antibodies (anti-TGF-beta1) allows the detection within two to three weeks of primitive hematopoietic cells called HPP-Q, which otherwise would not grow. However, the possibility of triggering cell proliferation by blocking the cell-surface TGF-beta receptors has not been investigated until now. We have tested here the efficiency of a blocking antibody against TGF-betaRII (anti-TGF-betaRII) on CD34(+)CD38(-) hematopoietic cells, a subpopulation enriched in primitive stem/progenitor cells, and compared its effect with that of anti-TGF-beta1. About twice as many HPP colony-forming cells were detected in the presence of anti-TGF-beta1 or anti-TGF-betaRII, compared to the control (p < 0.02). Moreover, anti-TGF-betaRII was as efficient as anti-TGF-beta1 for activating multipotent HPP-granulocyte erythroid macrophage megakaryocyte and HPP-Mix, bipotent HPP-granulocyte-macrophage (GM) and unipotent HPP-G, HPP-M and HPP-BFU-E. We therefore propose the use of anti-TGF-betaRII to release primitive cells from quiescence in the HPP-Q assay. This strategy could be extended to nonhematopoietic tissues, as TGF-beta1 may be a pleiotropic regulator of somatic stem cell quiescence.

Mitogenic effect of fibrinogen on hematopoietic cells: involvement of two distinct specific receptors, MFR and ICAM-1

In addition to its well-known functions in blood clotting and cell adhesion, fibrinogen has been reported to be a mitogen for lymphoid cell lines and for human hematopoietic progenitors. Two specific receptors, the mitogenic fibrinogen receptor (MFR) and intercellular adhesion molecule-1 (ICAM-1/CD54), have been identified as possible candidates for the mediation of the mitogenic effect of fibrinogen. However, it has been questioned whether the MFR and ICAM-1 are truly distinct molecules. Using an antiserum specific for the MFR, we demonstrate that the MFR is a cell surface molecule clearly distinct from ICAM-1. Both receptors can be expressed separately or coexpressed on different cell types. Moreover, they are regulated differently: ICAM-1 is calcium-dependent whereas the MFR is not and the MFR is down-regulated by fibrinogen whereas ICAM-1 is not. The inhibition by an anti-MFR serum of the mitogenic effect of fibrinogen confirms the mitogenic function of the MFR.

Co-stimulatory effects of steel factor, the c-kit ligand, on purified human hematopoietic progenitors in low cell density culture

Steel factor (SF), the ligand for the c-kit, also called kit ligand, stem cell factor, or mast cell growth factor, was evaluated on colony formation alone or in combination with other cytokines, from purified human hematopoietic CD34+ cells in low density cell culture. SF alone had a slight effect on granulocyte (G) and macrophage (M) colony formation. It synergized with other cytokines on colony formation from colony-forming unit-granulocyte, erythroid, macrophage, megakaryocyte (CFU-GEMM), erythroid and granulocyte-macrophage (CFU-GM) progenitors. However, combination of SF with lineage-specific factors, such as erythropoietin (Epo) or/and granulocyte colony-stimulating factor (G-CSF) was not sufficient for the proliferation of multipotential progenitors (CFU-GEMM). These multipotential progenitors required the presence of multi-lineage factors, such as interleukin 3 (IL3) or granulocytic-macrophage CSF(GM-CSF) for their development.