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. 2021 Apr 9;44(4):zsaa236.
doi: 10.1093/sleep/zsaa236.

A potential role for zinc in restless legs syndrome

Pan Chen  1 , Julia Bornhorst  2 , Stephanie Patton  3 , Kanika Bagai  4 , Rachana Nitin  5 , Mahfuzur Miah  1 , Dominic J Hare  6 , Kai Kysenius  7 , Peter J Crouch  7   8 , Lan Xiong  9 , Guy A Rouleau  9 , Tanja Schwerdtle  10 , James Connor  3 , Michael Aschner  1 , Aaron B Bowman  11 , Arthur S Walters  4
Affiliations

A potential role for zinc in restless legs syndrome

Pan Chen et al. Sleep. .

Abstract

Study objectives: Evaluate serum and brain noniron metals in the pathology and genetics of restless legs syndrome (RLS).

Methods: In two independent studies (cohorts 1 and 2), in which subjects either remained on medications or tapered off medications, we analyzed serum levels of iron, calcium, magnesium, manganese, copper, and zinc both in RLS patients and controls, and assessed the prevalence of the MEIS1 and BTBD9 risk alleles previously established through genome-wide association studies. Human brain sections and a nematode genetic model were also quantified for metal levels using mass spectrometry.

Results: We found a significant enrichment for the BTBD9 risk genotype in the RLS affected group compared to control (p = 0.0252), consistent with previous literature. Serum (p = 0.0458 and p = 0.0139 for study cohorts 1 and 2, respectively) and brain (p = 0.0413) zinc levels were significantly elevated in the RLS patients versus control subjects.

Conclusion: We show for the first time that serum and brain levels of zinc are elevated in RLS. Further, we confirm the BTBD9 genetic risk factor in a new population, although the zinc changes were not significantly associated with risk genotypes. Zinc and iron homeostasis are interrelated, and zinc biology impacts neurotransmitter systems previously linked to RLS. Given the modest albeit statistically significant increase in serum zinc of ~20%, and the lack of association with two known genetic risk factors, zinc may not represent a primary etiology for the syndrome. Further investigation into the pathogenetic role that zinc may play in restless legs syndrome is needed.

Keywords: essential metals; restless legs syndrome; zinc.

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Figures

Figure 1.
Figure 1.
Genotype study of risk SNPs for MEIS1 (rs2300478) and BTBD9 (rs9357271). For rs2300478, the risk allele is the presence of G instead of a T. We defined MEIS1 risk in our cohort as either heterozygous G/T alleles or homozygous G/G. Similarly, for BTBD9 the risk SNP is T instead of a C, where C is the minor allele in the population. In our study sample, BTBD9 risk is the presence of homozygous T/T alleles at the locus. A&B, risk allele enrichment based on the sex for BTBD9 (T/T) (A) and Meis1 (G/T or G/G) (B). (C–E), the enrichment of risk genotypes for BTBD9 (p = 0.0252), MEIS1 and either BTBD9/Meis1 (p = 0.0181). A chi-square test was used to compare the genotypes.
Figure 2.
Figure 2.
The levels of the individual metals in the serum and blood cells. The levels of magnesium (Mg), calcium (Ca), manganese (Mn), iron (Fe), copper (Cu), and zinc (Zn) were measured using ICPMS. (A–C) metals levels in the serum derived from study cohorts 1 (A), 2 (B), and the combined group (C). (D) Zinc concentrations in the lymphoblast cell lines were derived from RLS and control subjects. The data were analyzed by Multiple t-test with a Holm–Sidak correction (A, *p = 0.0458; B, *p = 0.0139; C, ***p = 0.0003).
Figure 3.
Figure 3.
Zinc levels in the substantia nigra of autopsy tissue by LA-ICP-MS. The substantia nigra sections from these autopsy tissues of RLS and control subjects (age and sex-matched) were imaged by LA-ICP-MS. Representative elemental maps for zinc (66Zn) (A) and quantitation of average zinc concentration (B). The data were analyzed by Student’s t-test (n = 4; *p = 0.0413).
Figure 4.
Figure 4.
The levels of the individual metals in the nematodes. The Control and BTBD9/hpo-9 (tm3719) mutant worms were synchronized at larva stage 1, washed and collected for ICPMS study. The levels of Mg, Mn, Fe, Cu, and Zn were measured. The data were analyzed by two-way ANOVA with Sidak’s multiple comparisons test (n = 4; *p = 0.0227).
Figure 5.
Figure 5.
Quantification of zinc transporter protein levels in RLS and Control peripheral lymphocytes. The levels of zinc transporter (ZIP8, ZIP14, and TRPM7) were determined with ELISA assays. No significant difference was observed in the protein levels of three zinc transporters. (A) ZIP8 (RLS: n=17, Control: 18); (B) ZIP14 (RLS: n = 15, Control: 17); (C) TPRM7 (RLS: n = 15, Control: 17). The box edges denote the upper and lower quartile range, with the box itself denoting the interquartile range, whiskers denote the full data range, and the horizontal line denotes the median data value for each group. The data were analyzed by Student’s t-test. For each experiment, n > 15 samples measured, and each sample was run in duplicate.
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References

    1. Allen RP, et al. ; International Restless Legs Syndrome Study Group (IRLSSG). Evidence-based and consensus clinical practice guidelines for the iron treatment of restless legs syndrome/Willis-Ekbom disease in adults and children: an IRLSSG task force report. Sleep Med. 2018;41:27–44. - PubMed
    1. Allen RP, et al. MRI measurement of brain iron in patients with restless legs syndrome. Neurology. 2001;56(2):263–265. - PubMed
    1. Earley CJ, et al. Abnormalities in CSF concentrations of ferritin and transferrin in restless legs syndrome. Neurology. 2000;54(8):1698–1700. - PubMed
    1. Connor JR, et al. Neuropathological examination suggests impaired brain iron acquisition in restless legs syndrome. Neurology. 2003;61(3):304–309. - PubMed
    1. O’Keeffe ST, et al. Iron status and restless legs syndrome in the elderly. Age Ageing. 1994;23(3):200–203. - PubMed

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