👤 Luc Boileau

Cognitive impairment is a common non-motor symptom of Parkinson's disease (PD), yet its underlying mechanisms remain poorly understood. Apolipoprotein E4 (APOE4), a genetic risk factor of Alzheimer's Disease, has been associated with PD-related cognitive impairment. However, findings are inconsistent, highlighting the need for further investigation. Neuroimaging studies have found gray matter abnormalities, mainly reductions in gray matter volume (GMV) and cortical thickness (CTh), in both cognitively impaired PD patients and APOE4 carriers. Yet, APOE4's role in these structural changes and their cognitive impact in PD is underexplored. This study aimed to determine whether APOE4 influences early structural brain differences in terms of GMV and CTh in PD prior to the emergence of cognitive dysfunction. A total of 51 PD APOE4 carriers and 120 non-carriers who were cognitively unimpaired from the Parkinson's Progression Markers Initiative (PPMI) database were included. T1-weighted MRI scans were used to calculate GMV and CTh in regions previously associated with PD-related cognitive impairment, including hippocampal subregions. Cognitive scores assessing global cognition and specific cognitive domains were used to examine associations between regions showing significant GMV or CTh group differences and cognitive performance. PD APOE4 carriers showed increased GMV in the left angular gyrus (AnG) and decreased GMV in the left nucleus accumbens (NAcc) compared to non-carriers, though neither survived multiple comparison correction. Left AnG GMV correlated with visuospatial function in both groups but did not remain significant after co-variate adjustment. Left NAcc GMV correlated with visuospatial function and working memory, but only in non-carriers even after co-variate adjustment. No group differences were observed in CTh measures and hippocampal subregion GMVs. This study suggests that APOE4 may not influence cognitive function in PD by affecting GMV and CTh. However, longitudinal analyses must confirm these observations. Show less

Clonal hematopoiesis (CH) is a common premalignant state in the blood and confers an increased risk of blood cancers and all-cause mortality. Identification of therapeutic targets in CH has been hindered by the lack of an ex vivo platform amenable for studying primary hematopoietic stem and progenitor cells (HSPCs). Here, we utilize an ex vivo co-culture system of HSPCs with bone marrow endothelial cells to perform CRISPR/Cas9 screens in mutant HSPCs. Our data reveal that loss of the histone demethylase family members Kdm3b and Jmjd1c specifically reduces the fitness of Idh2- and Tet2-mutant HSPCs. Kdm3b loss in mutant cells leads to decreased expression of critical cytokine receptors including Mpl, rendering mutant HSPCs preferentially susceptible to inhibition of downstream JAK2 signaling. Our study nominates an epigenetic regulator and an epigenetically regulated receptor signaling pathway as genotype-specific therapeutic targets and provides a scalable platform to identify genetic dependencies in mutant HSPCs. Significance: Given the broad prevalence, comorbidities, and risk of malignant transformation associated with CH, there is an unmet need to identify therapeutic targets. We develop an ex vivo platform to perform CRISPR/Cas9 screens in primary HSPCs. We identify KDM3B and downstream signaling components as genotype-specific dependencies in CH and myeloid malignancies. See related commentary by Khabusheva and Goodell, p. 1768. Show less

Men diagnosed with low-risk prostate cancer (PC) are increasingly electing active surveillance (AS) as their initial management strategy. While this may reduce the side effects of treatment for prostate cancer, many men on AS eventually convert to active treatment. PC is one of the most heritable cancers, and genetic factors that predispose to aggressive tumors may help distinguish men who are more likely to discontinue AS. To investigate this, we undertook a multi-institutional genome-wide association study (GWAS) of 5,222 PC patients and 1,139 other patients from replication cohorts, all of whom initially elected AS and were followed over time for the potential outcome of conversion from AS to active treatment. In the GWAS we detected 18 variants associated with conversion, 15 of which were not previously associated with PC risk. With a transcriptome-wide association study (TWAS), we found two genes associated with conversion ( Show less

One hundred fifty-four unrelated French Caucasian subjects were typed for 11 RFLPs at or near the APOA1-C3-A4 gene cluster on the long arm of chromosome 11. All subjects belonged to families having lived in the Toulouse area (in the southwest of France) for over three generations. Allele frequencies for each RFLP were in agreement with previous studies in Caucasian populations for the APOA1/SstI marker. Pairwise linkage disequilibrium was determined. Among the 55 pairs studied, 30 are newly reported. Only three significant nonrandom associations were found: APOA1/MspI-3'APOC3/SstI, APOA1/MspI-3'APOA4/XbaI, and APOA4/DraI-APOA4/XbaI. Extended 11-marker haplotypes were constructed. Haplotype frequencies were estimated by the maximum-likelihood procedure and compared to expected frequencies calculated under the assumption of equilibrium. Among the 37 estimated haplotypes, seven containing at least four nonrandomly associated alleles showed markedly increased frequencies. These results, obtained in a geographically homogeneous population, confirm the existence of disequilibrium in the apolipoprotein cluster, but to a lower extent than previously reported in Caucasian populations, which were geographically more heterogeneous. Show less