Research ArticleHuntington’s Disease

Evaluation of mutant huntingtin and neurofilament proteins as potential markers in Huntington’s disease

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Science Translational Medicine  12 Sep 2018:
Vol. 10, Issue 458, eaat7108
DOI: 10.1126/scitranslmed.aat7108
  • Fig. 1 Comparison of analyte concentrations across disease stage.

    Concentration of (A) CSF mHTT, (B) CSF NfL, and (C) plasma NfL in healthy controls, PreHD, and manifest HD (HD) patients. NfL values are natural log–transformed. P values were generated from multiple linear regressions and are Bonferroni-corrected.

  • Fig. 2 Comparison of analyte concentrations and clinical measures.

    Association within HD mutation carriers (n = 60) between CSF mHTT (green; A, D, G, and J), CSF NfL (blue; B, E, H, and K), plasma NfL (red; C, F, I, and L), and UHDRS clinical scores including functional (A to C), motor (D to F), and cognitive (G to L) measures. Scatter plots show unadjusted values. r and P values are age-adjusted, generated from Pearson’s partial correlations including age as a covariate. NfL values are natural log–transformed.

  • Fig. 3 Comparison of analyte concentrations and imaging measures.

    Association within HD mutation carriers (n = 49) between the analytes CSF mHTT (green; A to D), CSF NfL (blue; E to H), plasma NfL (red; I to L), and MRI volumetric measures of whole brain (A, E, and I), white matter (B, F, and J), gray matter (C, G, and K), and caudate (D, H, and L). All volumetric measures were calculated as a percentage of TIV. Scatter plots show unadjusted values. r and P values are age-adjusted, generated from Pearson’s partial correlations including age as a covariate. NfL values are natural log–transformed.

  • Fig. 4 Associations between biofluid analyte concentrations.

    Scatter plots showing correlation between CSF mHTT and CSF NfL concentrations (A; n = 60) and between CSF NfL and plasma NfL (B; n = 80). Scatter plots show unadjusted values. r and P values are unadjusted, generated from Pearson’s correlations. NfL values were natural log–transformed.

  • Fig. 5 Parallel assessment of the three analytes on diagnostic ability, within-subject stability, and sample size requirements.

    (A and B) ROC curves for (A) discrimination between controls (n = 20) and HD mutation carriers [n = 60; 95% confidence intervals (CIs) for AUCs: CSF mHTT, 1.000 to 1.000; CSF NfL, 0.876 to 0.989; plasma NfL, 0.852 to 0.976] and (B) discrimination between preHD and manifest HD (n = 60; 95% CIs for AUCs: CSF mHTT, 0.650 to 0.900; CSF NfL, 0.831 to 0.996; plasma NfL, 0.869 to 0.993). (C to E) Stability of CSF mHTT (green; C), CSF NfL (blue; D), and plasma NfL (red; E), over 6 to 8 weeks. Lines linking points indicate samples from the same individual (n = 15). (F) Sample size calculations for clinical trials in HD mutation carriers, implementing the reduction in these analytes as an outcome measure. NfL values are natural log–transformed. Log-transformed mHTT was used for sample size calculations. ICC, interclass correlation.

  • Fig. 6 Comparison of the temporal order of biofluid analytes relative to clinical and imaging measures.

    (A) Positional variance diagram produced from the EBM, applied to the 63 HD-CSF participants who had data for all biomarkers (controls, 15; preHD, 16; manifest HD, 32). (B) Reestimation of the positional variance in (A), using 100 bootstrap samples of the data, providing internal validation of the model’s findings. (C) Distribution of HD-CSF participants staged using the HD-CSF EBM, based on their collective data for all 12 measured variables. (D) Positional variance diagram from the EBM using the TRACK-HD cohort (24), now including plasma NfL and (E) similar results after reestimation with 100 bootstrap samples of the data. The positional variance diagrams represent the sequence of “events” (the individual measures going from normal to abnormal, identified by the EBM). Darker diagonal squares represent higher certainty of the biomarker becoming abnormal at the corresponding event where multiple event boxes colored indicate more uncertainty about its position. 1 indicates the earliest event. Proportion is with respect to each study group.

  • Table 1 Comparison of analyte concentrations.

    Intergroup differences were assessed using multiple linear regressions, which included either age or age and CAG as covariates. Significant differences are in bold. P values are Bonferroni-corrected. NfL concentrations were natural log–transformed. Values are means ± SD. CAG, CAG repeat length; ANOVA, analysis of variance; N/A, not applicable.

    AnalyteControl
    (n = 20)
    PreHD
    (n = 20)
    Manifest HD
    (n = 40)
    Comparison P values
    Adjusted forControl
    versus all
    mutation
    carriers
    ANOVAControl
    versus PreHD
    PreHD versus
    manifest HD
    CSF mHTT (fM)0 ± 046.4 ± 21.873.7 ± 28.7Age<0.0001<0.0001<0.00010.0010
    Age and CAGN/AN/AN/A0.1520
    CSF NfL
    (log pg/ml)
    6.7 ± 0.57.5 ± 0.78.5 ± 0.4Age<0.0001<0.0001<0.0001<0.0001
    Age and CAGN/AN/AN/A0.0148
    Plasma NfL
    (log pg/ml)
    2.9 ± 0.43.3 ± 0.64.2 ± 0.4Age<0.0001<0.0001<0.0001<0.0001
    Age and CAGN/AN/AN/A0.0008
  • Table 2 Association between the analytes and all assessed measures in HD mutation carriers.

    Values are Pearson’s r generated by partial correlations including age, or age and CAG, as covariates. Significant associations highlighted in bold. Volumetric measures are percentage of total intracranial volume (TIV).

    Clinical measures
    (n = 60)
    Adjusted forCSF mHTTCSF NfLPlasma NfL
    rP valuerP valuerP value
    Total functional capacityAge−0.3540.0060−0.3580.0054−0.512<0.0001
    Age and CAG−0.1220.3618−0.0380.7785−0.2910.0267
    Total motor scoreAge0.4440.00040.533<0.00010.695<0.0001
    Age and CAG0.2080.11810.2490.05940.525<0.0001
    Symbol digit modalities testAge−0.3330.0108−0.4630.0003−0.562<0.0001
    Age and CAG−0.0610.6551−0.1400.2985−0.3290.0125
    Stroop color namingAge−0.3510.0064−0.509<0.0001−0.650<0.0001
    Age and CAG−0.0720.5931−0.2080.1166−0.4540.0003
    Stroop word readingAge−0.3880.0024−0.528<0.0001−0.702<0.0001
    Age and CAG−0.1080.4178−0.2190.0989−0.525<0.0001
    Verbal fluency categoricalAge−0.3700.0040−0.4450.0004−0.577<0.0001
    Age and CAG−0.0970.4672−0.1030.4401−0.3400.0091
    Imaging measures
    (n = 49)
    Whole-brain volumeAge−0.2340.1102−0.4790.0006−0.4060.0042
    Age and CAG−0.0820.5862−0.4520.0014−0.2850.0518
    White matter volumeAge−0.1420.3360−0.3540.0135−0.2050.1626
    Age and CAG−0.0530.7246−0.3510.0157−0.1220.4150
    Gray matter volumeAge−0.2660.0674−0.5070.0002−0.4770.0006
    Age and CAG−0.1510.3116−0.3980.0057−0.4040.0049
    Caudate volumeAge−0.2110.1547−0.5390.0001−0.718<0.0001
    Age and CAG−0.0250.8682−0.3580.0144−0.628<0.0001

Supplementary Materials

  • www.sciencetranslationalmedicine.org/cgi/content/full/10/458/eaat7108/DC1

    Methods

    Fig. S1. Assessments for potential confounding variables.

    Fig. S2. The distribution of TRACK-HD participants staged using EBM.

    Fig. S3. The residual distributions for each measure used in the HD-CSF EBM.

    Table S1. Baseline characteristics of the HD-CSF cohort.

    Table S2. Characteristics of participants who opted out of optional MRI scan.

    Table S3. Characteristics of participants who opted out of optional repeated sampling.

  • This PDF file includes:

    • Methods
    • Fig. S1. Assessments for potential confounding variables.
    • Fig. S2. The distribution of TRACK-HD participants staged using EBM.
    • Fig. S3. The residual distributions for each measure used in the HD-CSF EBM.
    • Table S1. Baseline characteristics of the HD-CSF cohort.
    • Table S2. Characteristics of participants who opted out of optional MRI scan.
    • Table S3. Characteristics of participants who opted out of optional repeated sampling.

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