SLC6A3 and early-onset autosomal dominant Alzheimer disease: The phosphorylated tau protein and aggregated β-amyloid peptide for Alzheimer’s disease (AD), α-synuclein-containing Lewy bodies and altered dopamine transporter (DAT) imaging for Parkinson’s disease (PD) (Choudhury et al., 2022), superoxide dismutases (SOD) mutations for familial amyotrophic lateral sclerosis (ALS), and CAG repeats caused by Huntington’s gene mutations in Huntington’s disease are only a handful of several novel biological markers lately discovered (Rachakonda et al., 2004).