Anat Bar-Shira

Multicenter Analysis of Glucocerebrosidase Mutations in Parkinson's Disease

BACKGROUND Recent studies indicate an increased frequency of mutations in the gene encoding glucocerebrosidase (GBA), a deficiency of which causes Gauchers disease, among patients with Parkinsons disease. We aimed to ascertain the frequency of GBA mutations in an ethnically diverse group of patients with Parkinsons disease. METHODS Sixteen centers participated in our international, collaborative study: five from the Americas, six from Europe, two from Israel, and three from Asia. Each center genotyped a standard DNA panel to permit comparison of the genotyping results across centers. Genotypes and phenotypic data from a total of 5691 patients with Parkinsons disease (780 Ashkenazi Jews) and 4898 controls (387 Ashkenazi Jews) were analyzed, with multivariate logistic-regression models and the Mantel-Haenszel procedure used to estimate odds ratios across centers. RESULTS All 16 centers could detect two GBA mutations, L444P and N370S. Among Ashkenazi Jewish subjects, either mutation was found in 15% of patients and 3% of controls, and among non-Ashkenazi Jewish subjects, either mutation was found in 3% of patients and less than 1% of controls. GBA was fully sequenced for 1883 non-Ashkenazi Jewish patients, and mutations were identified in 7%, showing that limited mutation screening can miss half the mutant alleles. The odds ratio for any GBA mutation in patients versus controls was 5.43 across centers. As compared with patients who did not carry a GBA mutation, those with a GBA mutation presented earlier with the disease, were more likely to have affected relatives, and were more likely to have atypical clinical manifestations. CONCLUSIONS Data collected from 16 centers demonstrate that there is a strong association between GBA mutations and Parkinsons disease.

Jun NH2-Terminal Kinase Phosphorylation of p53 on Thr-81 Is Important for p53 Stabilization and Transcriptional Activities in Response to Stress

ABSTRACT The p53 tumor suppressor protein plays a key role in the regulation of stress-mediated growth arrest and apoptosis. Stress-induced phosphorylation of p53 tightly regulates its stability and transcriptional activities. Mass spectrometry analysis of p53 phosphorylated in 293T cells by active Jun NH2-terminal kinase (JNK) identified T81 as the JNK phosphorylation site. JNK phosphorylated p53 at T81 in response to DNA damage and stress-inducing agents, as determined by phospho-specific antibodies to T81. Unlike wild-type p53, in response to JNK stimuli p53 mutated on T81 (T81A) did not exhibit increased expression or concomitant activation of transcriptional activity, growth inhibition, and apoptosis. Forced expression of MKP5, a JNK phosphatase, in JNK kinase-expressing cells decreased T81 phosphorylation while reducing p53 transcriptional activity and p53-mediated apoptosis. Similarly transfection of antisense JNK 1 and -2 decreased T81 phosphorylation in response to UV irradiation. More than 180 human tumors have been reported to contain p53 with mutations within the region that encompasses T81 and the JNK binding site (amino acids 81 to 116). Our studies identify an additional mechanism for the regulation of p53 stability and functional activities in response to stress.

Recombinant ATM protein complements the cellular A-T phenotype

Ataxia-telangiectasia (A-T) is an autosomal recessive disorder characterized by neurodegeneration, immunodeficiency, cancer predisposition, genome instability and radiation sensitivity. The cellular phenotype of A-T points to defects in signal transduction pathways involved in activation of cell cycle checkpoints by free radical damage, and other pathways that mediate the transmission of specific mitogenic stimuli. The product of the responsible gene, ATM, belongs to a family of large proteins that contribute to maintaining genome stability and cell cycle progression in various organisms. A recombinant vector that stably expresses a full-length ATM protein is a valuable tool for its functional analysis. We constructed and cloned a recombinant, full-length open reading frame of ATM using a combination of vectors and hosts that overcame an inherent instability of this sequence. Recombinant ATM was stably expressed in insect cells using a baculovirus vector, albeit at a low level, and in human A-T cells using an episomal expression vector. An amino-terminal FLAG epitope added to the protein allowed highly specific detection of the recombinant molecule by immunoblotting, immunoprecipitation and immunostaining, and its isolation using immunoaffinity. Similar to endogenous ATM, the recombinant protein is located mainly in the nucleus, with low levels in the cytoplasm. Ectopic expression of ATM in A-T cells restored normal sensitivity to ionizing radiation and the radiomimetic drug neocarzinostatin, and a normal pattern of post-irradiation DNA synthesis, which represents an S-phase checkpoint. These observations indicate that the recombinant, epitope-tagged protein is functional. Introduction into this molecule of a known A-T missense mutation, Glu2904Gly, resulted in apparent instability of the protein and inability to complement the A-T phenotype. These findings indicate that the physiological defects characteristic of A-T cells result from the absence of the ATM protein, and that this deficiency can be corrected by ectopic expression of this protein.

Genotype-phenotype correlations between GBA mutations and Parkinson disease risk and onset

Background: Mutations in GBA and LRRK2 genes have been implicated in Parkinson disease (PD), particularly in Ashkenazi Jews. Methods: An Israeli Ashkenazi cohort of 420 patients with PD, 333 elderly controls, and 3,805 young controls was screened for eight GBA mutations, which are associated with mild (N370S, R496H) and severe (84GG, IVS2 + 1, V394L, D409H, L444P, RecTL) Gaucher disease. Patients with PD and elderly controls were also genotyped for LRRK2 G2019S. Results: GBA carrier frequency was 17.9% in patients with PD compared to 4.2% in elderly and 6.35% in young controls. The proportion of severe mutation carriers among PD patient GBA carriers was 29% compared to 7% among young controls. Severe and mild GBA mutations increased the risk of developing PD by 13.6- and 2.2-fold, and affected the average age at PD onset (AAO), 55.7 and 57.9 years, compared to 60.7 years in patients without known GBA or LRRK2 mutations. Conclusions: These data demonstrate genotype-phenotype correlations between different GBA mutations and Parkinson disease (PD) risk and AAO in Ashkenazi Jews. Additionally, an earlier AAO was observed in LRRK2 G2019S carrier PD patients. Finally, these data demonstrate that a surprisingly high frequency, more than one third of our patient population, carried a mutation in GBA or LRRK2.

A Novel Founder Mutation in the RNASEL Gene, 471delAAAG, Is Associated with Prostate Cancer in Ashkenazi Jews

HPC1/RNASEL was recently identified as a candidate gene for hereditary prostate cancer. We identified a novel founder frameshift mutation in RNASEL, 471delAAAG, in Ashkenazi Jews. The mutation frequency in the Ashkenazi population, estimated on the basis of the frequency in 150 healthy young women, was 4% (95% confidence interval [CI] 1.9%-8.4%). Among Ashkenazi Jews, the mutation frequency was higher in patients with prostate cancer (PRCA) than in elderly male control individuals (6.9% vs. 2.4%; odds ratio = 3.0; 95% CI 0.6-15.3; P=.17). 471delAAAG was not detected in the 134 non-Ashkenazi patients with PRCA and control individuals tested. The median age at PRCA diagnosis did not differ significantly between the Ashkenazi carriers and noncarriers included in our study. However, carriers received diagnoses at a significantly earlier age, compared with patients with PRCA who were registered in the Israeli National Cancer Registry (65 vs. 74.4 years, respectively; P<.001). When we examined two brothers with PRCA, we found a heterozygous 471delAAAG mutation in one and a homozygous mutation in the other. Loss of heterozygosity was demonstrated in the tumor of the heterozygous sib. Taken together, these data suggest that the 471delAAAG null mutation is associated with PRCA in Ashkenazi men. However, additional studies are required to determine whether this mutation confers increased risk for PRCA in this population.

The LRRK2 G2019S mutation in Ashkenazi Jews with Parkinson disease Is there a gender effect

Background: Mutations in the leucine-rich repeat kinase 2 (LRRK2) gene are the most common genetic determinant of Parkinson disease (PD) identified to date, and have been implicated in both familial and sporadic forms of the disease. The G2019S change in LRRK2 exon 41 has been associated with disease at varying frequencies in Asian, European, North American, and North African populations, and is particularly prevalent among Ashkenazi Jews. Methods: We assessed the occurrence of the LRRK2 G2019S, I2012T, I2020T, and R1441G/C/H mutations in our cohort of Jewish Israeli patients with PD, and determined the LRRK2 haplotypes in 76 G2019S-carriers detected and in 50 noncarrier Ashkenazi patients, using six microsatellite markers that span the entire gene. Results: Only the G2019S mutation was identified among our patients with PD, 14.8% in the Ashkenazi and 2.7% in the non-Ashkenazi patients, and in 26% and 10.6% of the Ashkenazi familial and apparently sporadic cases. The carrier frequencies in the Ashkenazi and non-Ashkenazi control samples were 2.4% and 0.4%. A common shared haplotype was detected in all non-Ashkenazi and half-Ashkenazi carriers and in all full-Ashkenazi carriers tested, except two. Women and patients with a positive family history of PD were significantly over-represented among the G2019S mutation carriers. Age at disease onset was similar in carriers and noncarriers. Conclusions: Our data suggest that the LRRK2 G2019S mutation plays an important role in the causality of familial and sporadic Parkinson disease (PD) in Israel and that gender affects its frequency among patients. Although testing symptomatic patients may help establish the diagnosis of PD, the value of screening asymptomatic individuals remains questionable until the penetrance and age-dependent risk of this mutation are more accurately assessed, and specific disease prevention or modifying interventions become available. GLOSSARY: LRRK2 = leucine-rich repeat kinase 2; PD = Parkinson disease.

Gait alterations in healthy carriers of the LRRK2 G2019S mutation

To test for an association between the LRRK2‐G2019S mutation and gait, we studied 52 first‐degree relatives of patients with Parkinsons disease (PD) who carry this mutation. An accelerometer quantified gait during usual‐walking, fast‐walking, and dual‐tasking. Noncarriers (n = 27) and carriers (n = 25) were similar with respect to age, gender, height, and gait speed during all conditions. During dual‐tasking and fast‐walking, gait variability and the amplitude of the dominant peak of the accelerometer signal were significantly altered among the carriers. These findings support the possibility of previously unidentified, presymptomatic motor changes among relatives who have an increased risk of developing PD. Ann Neurol 2010

The p.L302P mutation in the lysosomal enzyme gene SMPD1 is a risk factor for Parkinson disease

Objective: To study the possible association of founder mutations in the lysosomal storage disorder genes HEXA, SMPD1, and MCOLN1 (causing Tay-Sachs, Niemann-Pick A, and mucolipidosis type IV diseases, respectively) with Parkinson disease (PD). Methods: Two PD patient cohorts of Ashkenazi Jewish (AJ) ancestry, that included a total of 938 patients, were studied: a cohort of 654 patients from Tel Aviv, and a replication cohort of 284 patients from New York. Eight AJ founder mutations in the HEXA, SMPD1, and MCOLN1 genes were analyzed. The frequencies of these mutations were compared to AJ control groups that included large published groups undergoing prenatal screening and 282 individuals matched for age and sex. Results: Mutation frequencies were similar in the 2 groups of patients with PD. The SMPD1 p.L302P was strongly associated with a highly increased risk for PD (odds ratio 9.4, 95% confidence interval 3.9–22.8, p < 0.0001), as 9/938 patients with PD were carriers of this mutation compared to only 11/10,709 controls. Conclusions: The SMPD1 p.L302P mutation is a novel risk factor for PD. Although it is rare on a population level, the identification of this mutation as a strong risk factor for PD may further elucidate PD pathogenesis and the role of lysosomal pathways in disease development.

Differential effects of severe vs mild GBA mutations on Parkinson disease

Objective: To better define the genotype-phenotype correlations between the type of GBA (glucosidase, beta, acid) mutation, severe or mild, and the risk and age at onset (AAO), and potential mechanism of Parkinson disease (PD). Methods: We analyzed 1,000 patients of Ashkenazi-Jewish descent with PD for 7 founder GBA mutations, and conducted a meta-analysis of risk and AAO according to GBA genotype (severe or mild mutation). The meta-analysis included 11,453 patients with PD and 14,565 controls from worldwide populations. The statistical analysis was done with and without continuity correction (constant or empirical), considering biases that could potentially affect the results. Results: Among Ashkenazi-Jewish patients with PD, the odds ratios for PD were 2.2 and 10.3 for mild and severe GBA mutation carriers, respectively. The observed frequency of severe GBA mutation carriers among patients with PD was more than 4-fold than expected (4.4% vs 0.9%, respectively, p < 0.0001, Fisher exact test). In the different models of the meta-analysis, the odds ratios for PD ranged between 2.84 and 4.94 for mild GBA mutation carriers and 9.92 and 21.29 for severe GBA mutation carriers (p < 1 × 10−6 for all analyses). Pooled analysis demonstrated AAO of 53.1 (±11.2) and 58.1 (±10.6) years for severe and mild GBA mutation carriers, respectively (p = 4.3 × 10−5). Conclusions: These data demonstrate that mild and severe heterozygous GBA mutations differentially affect the risk and the AAO of PD. Our results have important implications for genetic counseling and clinical follow-up.

GBA mutations are associated with Rapid Eye Movement Sleep Behavior Disorder.

Rapid eye movement sleep behavior disorder and GBA mutations are both associated with Parkinsons disease. The GBA gene was sequenced in idiopathic rapid eye movement sleep behavior disorder patients (n = 265), and compared to controls (n = 2240). Rapid eye movement sleep behavior disorder questionnaire was performed in an independent Parkinsons disease cohort (n = 120). GBA mutations carriers had an OR of 6.24 (10.2% in patients vs. 1.8% in controls, P < 0.0001) for rapid eye movement sleep behavior disorder, and among Parkinsons disease patients, the OR for mutation carriers to have probable rapid eye movement sleep behavior disorder was 3.13 (P = 0.039). These results demonstrate that rapid eye movement sleep behavior disorder is associated with GBA mutations, and that combining genetic and prodromal data may assist in identifying individuals susceptible to Parkinsons disease.