The purpose of this notice of funding opportunity (NOFO) is to support rigorous analytical validation of method(s) used for measuring biomarkers for neurological and neuromuscular disorders for use in clinical trials or clinical practice. Applicants must justify the unmet need for the biomarker(s) and measurement methods and specify one or two context(s) of use for the biomarker(s). Activities supported include optimizing and evaluating the accuracy, precision, reportable range, and analytical sensitivity and specificity of the detection method across multiple sites and operators and establishing reference intervals and quality control procedures. Multi-site applications are expected but not required.