👤 Alison M Muir

Physical activity (PA) has been associated with reduced Alzheimer's disease (AD) risk, but whether protective effects vary across genetic risk levels remains unclear. Previous studies were limited by self-reported PA measures and simplified genetic models. In this study, we aimed to examine the association between accelerometer-measured physical activity and the risk of incident AD in a large population-based cohort, and to explore potential interactions between PA and polygenic risk scores for AD. We analyzed 93,578 UK Biobank participants aged 40-70 years with accelerometer data and genome-wide genotyping. PA was measured continuously (milligravity, mg) and dichotomized at the optimal point from maximally selected rank statistics. Genetic risk was assessed using polygenic risk scores (PRS) and APOE ε4 status. Cox models estimated hazard ratios for incident AD across genetic risk strata during median 15.5-year follow-up. Among 401 AD cases, high PA reduced risk by 48% (HR 0.517; 95% CI 0300-0.891), while high PRS increased risk nearly twofold (HR 2.423; 95% CI 1.757-3.343). PA's protective association remained consistent across all PRS and APOE ε4 strata. No significant multiplicative or additive interaction was found between PA and genetic risk (RERI = - 0.566, 95% CI - 4.574-3.441). Dose-response analysis revealed maximum benefit with optimal threshold at 21.7 mg corresponding to light-intensity activity. Objectively measured PA substantially reduces AD risk regardless of genetic predisposition. Even light-intensity activity provides meaningful protection, supporting PA as a broadly applicable preventive strategy across all genetic risk levels. Show less

The MAST family of microtubule-associated serine-threonine kinases (STKs) have distinct expression patterns in the developing and mature human and mouse brain. To date, only MAST1 has been conclusively associated with neurological disease, with de novo variants in individuals with a neurodevelopmental disorder, including a mega corpus callosum. Using exome sequencing, we identify MAST3 missense variants in individuals with epilepsy. We also assess the effect of these variants on the ability of MAST3 to phosphorylate the target gene product ARPP-16 in HEK293T cells. We identify de novo missense variants in the STK domain in 11 individuals, including 2 recurrent variants p.G510S (n = 5) and p.G515S (n = 3). All 11 individuals had developmental and epileptic encephalopathy, with 8 having normal development prior to seizure onset at <2 years of age. All patients developed multiple seizure types, 9 of 11 patients had seizures triggered by fever and 9 of 11 patients had drug-resistant seizures. In vitro analysis of HEK293T cells transfected with MAST3 cDNA carrying a subset of these patient-specific missense variants demonstrated variable but generally lower expression, with concomitant increased phosphorylation of the MAST3 target, ARPP-16, compared to wild-type. These findings suggest the patient-specific variants may confer MAST3 gain-of-function. Moreover, single-nuclei RNA sequencing and immunohistochemistry shows that MAST3 expression is restricted to excitatory neurons in the cortex late in prenatal development and postnatally. In summary, we describe MAST3 as a novel epilepsy-associated gene with a potential gain-of-function pathogenic mechanism that may be primarily restricted to excitatory neurons in the cortex. ANN NEUROL 2021;90:274-284. Show less

To identify susceptibility loci for meningioma, we conducted a genome-wide association study of 859 affected individuals (cases) and 704 controls with validation in two independent sample sets totaling 774 cases and 1,764 controls. We identified a new susceptibility locus for meningioma at 10p12.31 (MLLT10, rs11012732, odds ratio = 1.46, P(combined) = 1.88 × 10(-14)). This finding advances our understanding of the genetic basis of meningioma development. Show less