title: β-glucuronidase mRNA levels are correlated with gait and working memory in premutation females: understanding the role of FMR1 premutation alleles.
abstract: Fragile X tremor ataxia syndrome (FXTAS) is a late-onset disorder manifesting in a proportion of FMR1 premutation individuals (PM: 55-199 CGG triplet expansions). FXTAS is associated with elevated levels of FMR1 mRNA which are toxic. In this study, relationships between neurocognitive and intra-step gait variability measures with mRNA levels, measured in blood samples, were examined in 35 PM and 35 matched control females. The real-time PCR assays measured FMR1 mRNA, and previously used internal control genes: β-Glucuronidase (GUS), Succinate Dehydrogenase 1 (SDHA) and Eukaryotic Translation Initiation Factor 4A (EI4A2). Although there was significant correlation of gait variability with FMR1 mRNA levels (p = 0.004) when normalized to GUS (FMR1/GUS), this was lost when FMR1 was normalized to SDHA and EI4A2 (2IC). In contrast, GUS mRNA level normalized to 2IC showed a strong correlation with gait variability measures (p < 0.007), working memory (p = 0.001) and verbal intelligence scores (p = 0.008). PM specific changes in GUS mRNA were not mediated by FMR1 mRNA. These results raise interest in the role of GUS in PM related disorders and emphasise the importance of using appropriate internal control genes, which have no significant association with PM phenotype, to normalize FMR1 mRNA levels.
authors.affiliation: School of Psychological Sciences and Monash Institute of Cognitive and Clinical Neurosciences, Monash University, Clayton, Victoria, 3800, Australia.
authors.forename: C M
authors.initials: CM
authors.lastname: Kraan
authors.affiliation: School of Psychological Sciences and Monash Institute of Cognitive and Clinical Neurosciences, Monash University, Clayton, Victoria, 3800, Australia.
authors.forename: K M
authors.initials: KM
authors.lastname: Cornish
authors.affiliation: Centre for Molecular, Environmental, Genetic and Analytic Epidemiology, University of Melbourne Carlton, Victoria, 3053, Australia.
authors.forename: Q M
authors.initials: QM
authors.lastname: Bui
authors.affiliation: Cyto-molecular Diagnostic Research Laboratory, Victorian Clinical Genetics Services and Murdoch Childrens Research Institute, Royal Children's Hospital, Melbourne, Victoria, 3052, Australia.
authors.forename: X
authors.initials: X
authors.lastname: Li
authors.affiliation: Cyto-molecular Diagnostic Research Laboratory, Victorian Clinical Genetics Services and Murdoch Childrens Research Institute, Royal Children's Hospital, Melbourne, Victoria, 3052, Australia.|Department of Paediatrics, The University of Melbourne, Melbourne, Victoria, 3052, Australia.
authors.forename: H R
authors.initials: HR
authors.lastname: Slater
authors.affiliation: Cyto-molecular Diagnostic Research Laboratory, Victorian Clinical Genetics Services and Murdoch Childrens Research Institute, Royal Children's Hospital, Melbourne, Victoria, 3052, Australia.
authors.forename: D E
authors.initials: DE
authors.lastname: Godler
mesh_terms: D000328:Adult; D001259:Ataxia / Q000097:blood / Q000150:complications* / Q000235:genetics; D016022:Case-Control Studies; D005260:Female; D051860:Fragile X Messenger Ribonucleoprotein 1 / Q000097:blood / Q000235:genetics*; D005600:Fragile X Syndrome / Q000097:blood / Q000150:complications* / Q000235:genetics; D005684:Gait / Q000235:genetics*; D005966:Glucuronidase / Q000097:blood / Q000235:genetics*; D006801:Humans; D008297:Male; D008570:Memory, Short-Term; D008875:Middle Aged; D009154:Mutation; D012333:RNA, Messenger / Q000097:blood; D060888:Real-Time Polymerase Chain Reaction / Q000592:standards; D014202:Tremor / Q000097:blood / Q000150:complications* / Q000235:genetics; D019680:Trinucleotide Repeat Expansion
chemical_list: D051860:Fragile X Messenger Ribonucleoprotein 1; D005966:Glucuronidase; D012333:RNA, Messenger; C497683:FMR1 protein, human