The erythrocyte sedimentation rate as a diagnostic biomarker for neuroacanthocytosis syndromes

Chorea-acanthocytosis (ChAc) and McLeod syndrome (MLS) are the core diseases among the group of rare neurodegenerative disorders that comprise neuroacanthocytosis syndrome (NAS). Both ChAc and MLS patients present with an increased number of irregularly spiky erythrocytes, so-called acanthocytes. The detection of acanthocytes is often a crucial parameter in the diagnosis of NAS. However, this approach is error-prone and not very reliable, typically explaining the misdiagnosis of NAS patients. Based on the standard Westergren method, we show that compared with that in healthy controls, the erythrocyte sedimentation rate (ESR) with a two-hour read-out is significantly prolonged in ChAc and MLS with no overlap. Thus, the ESR is a clear, robust and easily obtained diagnostic marker. Mechanistically, by applying modern colloidal physics, we show that acanthocyte aggregation and plasma fibrinogen levels slow the sedimentation process. Apart from its diagnostic value, ESR may also be the first biomarker for monitoring treatments for NAS patients. Further studies are required to test whether the ESR may also detect other NASs. In addition to medical progress, this study is also a hallmark of the physical view of the erythrocyte sedimentation process by describing anticoagulated blood in stasis as a percolating gel, allowing the application of colloidal physics theory.