Plasma neurofilament light chain concentrations are elevated in youth-onset type 2 diabetes and associated with neuropathy.

BACKGROUND AND AIMS: The lack of easily measurable biomarkers remains a challenge in executing clinical trials for diabetic neuropathy (DN). Plasma Neurofilament light chain (NFL) concentration is a promising biomarker in immune-mediated neuropathies. Longitudinal studies evaluating NFL in DN have not been performed. METHODS: A nested case-control study was performed on participants with youth-onset type 2 diabetes enrolled in the prospective Treatment Options for Type 2 Diabetes in Adolescents and Youth (TODAY) study. Plasma NFL concentrations were measured at 4-year intervals from 2008 to 2020 in 50 participants who developed DN and 50 participants with type 2 diabetes who did not develop DN. RESULTS: NFL concentrations were similar in the DN and no DN groups at the first assessment. Concentrations were higher in DN participants at all subsequent assessment periods (all p < .01). NFL concentrations increased over time in both groups, with higher degrees of change in DN participants (interaction p = .045). A doubling of the NFL value at Assessment 2 in those without DN increased the odds of ultimate DN outcome by an estimated ratio of 2.86 (95% CI: [1.30, 6.33], p = .0046). At the final study visit, positive Spearman correlations (controlled for age, sex, diabetes duration, and BMI) were observed between NFL and HbA1c (0.48, p < .0001), total cholesterol (0.25, p = .018), and low-density lipoprotein (LDL (0.30, p = .0037)). Negative correlations were observed with measures of heart rate variability (-0.42 to -0.46, p = <.0001). INTERPRETATION: The findings that NFL concentrations are elevated in individuals with youth-onset type 2 diabetes, and increase more rapidly in those who develop DN, suggest that NFL could be a valuable biomarker for DN.

Disease Progression in Charcot-Marie-Tooth Disease Related to MPZ Mutations: A Longitudinal Study.

OBJECTIVE: The paucity of longitudinal natural history studies in MPZ neuropathy remains a barrier to clinical trials. We have completed a longitudinal natural history study in patients with MPZ neuropathies across 13 sites of the Inherited Neuropathies Consortium. METHODS: Change in Charcot-Marie-Tooth Examination Score (CMTES) and Rasch modified CMTES (CMTES-R) were evaluated using longitudinal regression over a 5-year period in subjects with MPZ neuropathy. Data from 139 patients with MPZ neuropathy were examined. RESULTS: The average baseline CMTES and CMTES-R were 10.84 (standard deviation [SD] = 6.0, range = 0-28) and 14.60 (SD = 7.56, range = 0-32), respectively. A mixed regression model showed significant change in CMTES at years 2-5 (mean change from baseline of 0.87 points at 2 years, p = 0.008). Subgroup analysis revealed greater change in CMTES at 2 years in subjects with axonal as compared to demyelinating neuropathy (mean change of 1.30 points [p = 0.016] vs 0.06 points [p = 0.889]). Patients with a moderate baseline neuropathy severity also showed more notable change, by estimate, than those with mild or severe neuropathy (mean 2-year change of 1.14 for baseline CMTES 8-14 [p = 0.025] vs -0.03 for baseline CMTES 0-7 [p = 0.958] and 0.25 for baseline CMTES ≥ 15 [p = 0.6897]). The progression in patients harboring specific MPZ mutations was highly variable. INTERPRETATION: CMTES is sensitive to change over time in adult patients with axonal but not demyelinating forms of MPZ neuropathy. Change in CMTES was greatest in patients with moderate baseline disease severity. These findings will inform future clinical trials of MPZ neuropathies. ANN NEUROL 2023;93:563-576.

Limb Girdle Muscular Dystrophies.

The limb girdle muscular dystrophies (LGMDs) are genetic muscle diseases with primary skeletal muscle involvement in persons with the ability to walk independently at some point in the disease course. They usually have increased creatine kinase levels along with patterns of fatty and fibrous deposition on muscle imaging and/or dystrophic features on muscle biopsy. Distinctive clinical features provide valuable diagnostic clues to the diagnosis and sometimes treatment of these disorders. The advent of gene and cell-based therapies; gene replacement, editing, and modulation; along with stem cell and small molecule therapies may significantly ameliorate clinical severity in the LGMDs.