Jiraanont, Poonnada

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Jiraanont, Poonnada
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poonnada.ji@kmitl.ac.th

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    FMR1 Protein Expression Correlates with Intelligence Quotient in Both Peripheral Blood Mononuclear Cells and Fibroblasts from Individuals with an FMR1 Mutation
    (2024-06-01)
    Jiraanont, Poonnada
    ;
    Zafarullah, Marwa
    ;
    Sulaiman, Noor
    ;
    Espinal, Glenda M.
    ;
    Randol, Jamie L.
    Fragile X syndrome (FXS) is the most common heritable form of intellectual disability and is caused by CGG repeat expansions exceeding 200 (full mutation). Such expansions lead to hypermethylation and transcriptional silencing of the fragile X messenger ribonucleoprotein 1 (FMR1) gene. As a consequence, little or no FMR1 protein (FMRP) is produced; absence of the protein, which normally is responsible for neuronal development and maintenance, causes the syndrome. Previous studies have demonstrated the causal relationship between FMRP levels and cognitive abilities in peripheral blood mononuclear cells (PBMCs) and dermal fibroblast cell lines of patients with FXS. However, it is arguable whether PBMCs or fibroblasts would be the preferred surrogate for measuring molecular markers, particularly FMRP, to represent the cognitive impairment, a core symptom of FXS. To address this concern, CGG repeats, methylation status, FMR1 mRNA, and FMRP levels were measured in both PBMCs and fibroblasts derived from 66 individuals. The findings indicated a strong association between FMR1 mRNA expression levels and CGG repeat numbers in PBMCs of premutation males after correcting for methylation status. Moreover, FMRP expression levels from both PBMCs and fibroblasts of male participants with a hypermethylated full mutation and with mosaicism demonstrated significant association between the intelligence quotient levels and FMRP levels, suggesting that PBMCs may be preferable for FXS clinical studies, because of their greater accessibility.
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    The apolipoprotein gene: a modulating role on brain volume and cognitive function in carriers of the fragile X premutation
    (2026-03-01)
    Jiraanont, Poonnada
    ;
    Wang, Jun Yi
    ;
    Durbin-Johnson, Blythe
    ;
    Hwang, Ye Hyun
    ;
    Hessl, David
    AbstractFragile X-associated tremor/ataxia syndrome (FXTAS), caused by the FMR1 premutation allele, is associated with brain degeneration, yet the mechanisms behind this neurodegeneration still need to be elucidated. Apoε polymorphism has been widely implicated in brain aging in cognitively healthy individuals and brain deterioration in Alzheimer's disease. This study aimed to examine the interaction of Apoε genotypes, FXTAS clinical symptoms, FMR1 molecular measures, and age, towards brain pathophysiology and cognitive functions.This longitudinal study includes MRI data collected from 205 male premutation carriers with and without FXTAS clinical symptoms and compared to 86 healthy male controls aged 40–85 years. The investigation includes FXTAS-related brain volumes, IQ, self-control behaviors, FMR1 molecular measures, and Apoε genotypes.In carriers with FXTAS, the presence of the Apoε2 allele showed a possible association with more favorable neuroimaging markers, such as reduced white matter hyperintensities, and lower incidence of the middle cerebellar peduncle sign, patterns that were not observed in carriers without FXTAS.Specifically, the presence of Apoε2 allele exhibited a potential protective effect on brain degeneration, and cognitive functions among FXTAS patients; on the contrary, the Apoε4 allele was associated with a worsening of brain volume and brain degeneration in carriers with no FXTAS symptoms. The identification of Apoε genotypes in FMR1 premutation carriers before any clinical symptoms of FXTAS are observed may improve symptomatic management leading to better outcomes for these individuals.
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    Corrigendum to “The apolipoprotein gene: a modulating role on brain volume and cognitive function in carriers of the fragile X premutation” [Neurobiology of Disease 2026 Feb 2; 220:107292, Page 1–13]
    (2026-07-01)
    Jiraanont, Poonnada
    ;
    Wang, Jun Yi
    ;
    Durbin-Johnson, Blythe
    ;
    Hwang, Ye Hyun
    ;
    Hessl, David
    The authors regret that they omitted to submit updated captions for Figs. 1, 2 and 3 during revision. The correct figure captions are as follows. Fig. 1 Representative segmentations of white matter hyperintensities (A-F), whole brain (G-L), cerebellum (G-L), brainstem (G-L), and lateral ventricles (LV, G-L) in a healthy control (A, D, G, & J), a premutation carrier without FXTAS (B, E, H, & K), and a premutation carrier with FXTAS (C, F, I, & L) all at the age of 62 years. (A-C) Axial views of the FLAIR scans showing segmented white matter hyperintensities including the splenium sign of the corpus callosum (dash arrow) in C. (DF) Coronal views of the FLAIR scans showing the segmented white matter hyperintensities including the splenium sign of the corpus callosum (dash arrow) and the MCP sign (straight arrows) in F. (G-I) Sagittal views of the T1 images showing the segmentation of the brain, cerebellum, brainstem, and LV. (J-L) Coronal views of the T1 images showing the segmentation of the brain, cerebellum, brainstem, and LV.