Embracing Monogenic Parkinson's Disease: The MJFF Global Genetic PD Cohort

BACKGROUND

As gene-targeted therapies are increasingly being developed for Parkinson's disease (PD), identifying and characterizing carriers of specific genetic pathogenic variants is imperative. Only a small fraction of the estimated number of subjects with monogenic PD worldwide are currently represented in the literature and availability of clinical data and clinical trial-ready cohorts is limited.

OBJECTIVE

The objectives are to (1) establish an international cohort of affected and unaffected individuals with PD-linked variants; (2) provide harmonized and quality-controlled clinical characterization data for each included individual; and (3) further promote collaboration of researchers in the field of monogenic PD.

METHODS

We conducted a worldwide, systematic online survey to collect individual-level data on individuals with PD-linked variants in SNCA, LRRK2, VPS35, PRKN, PINK1, DJ-1, as well as selected pathogenic and risk variants in GBA and corresponding demographic, clinical, and genetic data. All registered cases underwent thorough quality checks, and pathogenicity scoring of the variants and genotype-phenotype relationships were analyzed.

RESULTS

We collected 3888 variant carriers for our analyses, reported by 92 centers (42 countries) worldwide. Of the included individuals, 3185 had a diagnosis of PD (ie, 1306 LRRK2, 115 SNCA, 23 VPS35, 429 PRKN, 75 PINK1, 13 DJ-1, and 1224 GBA) and 703 were unaffected (ie, 328 LRRK2, 32 SNCA, 3 VPS35, 1 PRKN, 1 PINK1, and 338 GBA). In total, we identified 269 different pathogenic variants; 1322 individuals in our cohort (34%) were indicated as not previously published.

CONCLUSIONS

Within the MJFF Global Genetic PD Study Group, we (1) established the largest international cohort of affected and unaffected individuals carrying PD-linked variants; (2) provide harmonized and quality-controlled clinical and genetic data for each included individual; (3) promote collaboration in the field of genetic PD with a view toward clinical and genetic stratification of patients for gene-targeted clinical trials. © 2023 The Authors. Movement Disorders published by Wiley Periodicals LLC on behalf of International Parkinson and Movement Disorder Society.

Factors affecting the binding between fusicoccin and plasma membranes from maize roots

Plasma membranes have been purified from roots of maize (Zea mays L.) using a two-phase aqueous polymer system, dextran-polyethylene glycol. The plant material was homogenized in the presence of a mixture of natural protease inhibitors from potato (Solanum tuberosum L.); these inhibitors have been shown to be more effective than phenylmethylsulfonyl fluoride in suppressing the endogenous proteases in maize roots. Inhibition of proteolysis in the homogenization medium markedly increased (about tenfold) the number of lowaffinity binding sites for fusicoccin (FC). In addition, storage of plasma membranes at -20° C decreased both the number of the low-affinity sites and their dissociation constant (KD); this effect was in all probability caused by lipid peroxidation. The presence of EDTA throughout isolation and storage of the plasma membranes stabilized the parameters of FC binding to the membranes. The kinetics of binding of [(3)H]dihydroFC and the competition between [(3)H]dihydroFC and FCs A, C, J, and H were determined for the low-affinity sites. It was found that (i) the rate constant of association between FC and the low-affinity binding sites is about two orders of magnitude lower than that for the high-affinity sites; (ii) different FCs can be arranged in the order of decreasing avidity for the low-affinity FCbinding site: FC A>FC C>FC J>FC H.

Comparison of the biological activity of fusicoccin in higher plants with its binding to plasma membranes

The concentration dependences of the binding of fusicoccins (FCs) A, B, C, D, J and H to plasma membranes isolated from maize (Zea mays L.) roots have been studied in parallel with the effects of these compounds on elongation and (86)Rb transport in detached maize roots. The dissociation constants obtained showed a good correlation between the affinity of the FCs for the plasmalemma and their biological activity. However, the range of physiologically active FC concentrations proved to be about two orders of magnitude higher than that calculated from the dissociation constants. It was also shown that Vicia faba L. mesophyll protoplasts, unlike isolated plasma membranes, have two FC-binding sites, one with a K D similar to that of the isolated plasmalemma while the other has a substantially higher K D , apparently corresponding to the physiologically active state of the FC-binding proteins.