Abstract
Substantia nigra (SN) hyperechogenicity is present in most Parkinson’s disease (PD) cases but is occasionally absent in some. To date, age, gender, disease severity, and other factors have been reported to be associated with SN hyperechogenicity in PD. Previous studies have discovered that excess iron deposition in the SN underlies its hyperechogenicity in PD, which may also indicate the involvement of genes associated with iron metabolism in hyperechogenicity. The objective of our study is to explore the potential associations between variants in iron metabolism-associated genes and SN echogenicity in Han Chinese PD. Demographic profiles, clinical data, SN echogenicity and genotypes were obtained from 221 Han Chinese PD individuals with a sufficient bone window. Serum ferritin levels were quantified in 92 of these individuals by immunochemical assay. We then compared factors between PD individuals with SN hyperechogenicity and those with SN hypoechogenicity to identify factors that predispose to SN hyperechogenicity. Of our 221 participants, 122 (55.2%) displayed SN hyperechogenicity, and 99 (44.8%) displayed SN hypoechogenicity. Gender and serum ferritin levels were found to be associated with SN hyperechogenicity. In total, 14 genes were included in the sequencing part. After data processing, 34 common single nucleotide polymorphisms were included in our further analyses. In our data, we also found a significantly higher frequency of PANK2 rs3737084 (genotype: OR = 2.07, P = 0.013; allele: OR = 2.51, P = 0.002) in the SN hyperechogenic group and a higher frequency of PLA2G6 rs731821 (genotype: OR = 0.45, P = 0.016; allele: OR = 0.44, P = 0.011) in the SN hypoechogenic group. However, neither of the two variants was found to be correlated with serum ferritin. This study demonstrated that genetic factors, serum ferritin level, and gender may explain the interindividual variability in SN echogenicity in PD. This is an explorative study, and further replication is warranted in larger samples and different populations.
Highlights
Parkinson’s disease (PD) is the second most common neurodegenerative disease, characterized by motor and non-motor symptoms such as bradykinesia, rigidity, resting tremor, hyposmia, and rapid eye movement sleep behaviour disorder[1,2]
PANK2, COASY, PLA2G6, and other genes related to iron homeostasis have been reported to cause diseases related to abnormal iron accumulation, such as neurodegeneration with brain iron accumulation (NBIA) and infantile neuroaxonal dystrophy (INAD)
The proportion of males was significantly higher among the individuals with Substantia nigra (SN)+ than among those with SN− (P < 0.001), whereas age, disease duration, Hoehn and Yahr stage, and Unified Parkinson Disease Rating Scale (UPDRS)-III ratings were similar between the two groups (Supplemental Table 1)
Summary
Parkinson’s disease (PD) is the second most common neurodegenerative disease, characterized by motor and non-motor symptoms such as bradykinesia, rigidity, resting tremor, hyposmia, and rapid eye movement sleep behaviour disorder[1,2]. Substantia nigra hyperechogenicity (SN+) under transcranial sonography (TCS) is a common feature of PD that enables reliable diagnosis of PD with high sensitivity and specificity[3,4]. Www.nature.com/scientificreports we aimed to compare the clinical characteristics and genotypes of PD individuals with different SN echogenicities to determine whether there are genetic factors that play a role in SN+ in PD. This is an explorative study and requires further replication
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
