Dear Researcher,
Amyotrophic lateral sclerosis (ALS) is a complex neurodegenerative disease that causes progressive muscle weakness through loss of upper and lower motor neurons. The disease is fatal. However, ALS shows considerable variability in clinical presentations and prognosis between patients. Therefore, there is an urgent need to identify biomarkers that would help with the diagnosis, prognosis and ultimately treatment of ALS.
ALS Biomarker Characteristics
In their review, Kirk et al.,(2019) identify 6 attributes that are desirable in a biomarker:
1. Specificity to disease
2. Reproducibility
3. Appearance in the early stage of the disease
4. Stability across the diurnal period
5. Independence of dietary status and behaviour
6. The biomarker should demonstrate a notable change as the disease progresses
Of the 37 ALS biomarkers described, creatinine kinase in blood and p75 neurotrophin receptor Extracellular domain (NGFR, p75ECD) in urine receive the highest score of 3.5 on a scale of 0 - 6. In contrast to creatinine kinase, urinary p75ECD increases as disease progresses, and is inversely correlated with the ALSFRS-R score (the ALS Functional Rating Scale - Revised is a validated instrument for monitoring the progression of disability in patients with ALS). p75ECD has also been shown to be diurnally stable Shepheard et al.,(2017) and is present in significantly higher concentrations in ALS patients compared to patients with other neurological diseases Jia et al.,(2017). These factors as well as the non-invasive method of obtaining a urinary sample make p75ECD an excellent biomarker for ALS prognosis.
Urine p75ECD Quantification and the Importance of Normalisation
Biosensis offers the only NGFR/p75ECD ELISA kit (BEK-2239) extensively validated for accurate quantification in human urine, with excellent inter-assay (7.9-10.9%), intra-batch (3.2-6.9%) and inter-batch precision (7.5-9.9%).
