Characterize the natural history of ALSP by imaging, biomarkers, and standardized clinical measurements to inform the design of future clinical trials testing novel therapeutics for ALSP.

ALSP is a rare, rapidly progressing fatal neurologic disorder commonly caused by dominant variants in the CSF1R gene. The pathological hallmarks include demyelination of brain white matter, swollen axons, and pigmented glial cells. Clinically, ALSP is characterized by a constellation of symptoms including personality changes, cognitive dysfunction and motor impairments. There are no FDA approved treatments for ALSP. Limited natural history data is available to inform development of therapeutics for ALSP.

28 participants with confirmed CSF1R gene mutation meeting study eligibility criteria have been enrolled as of 9/2/2022. Among these, 17 were symptomatic and 11 were asymptomatic carriers, 13 were women and mean age at Screening visit was 46±13 years. Study enrollment is ongoing. Detailed study design and baseline characteristics of enrolled participants will be presented.

This is the first systematic prospective study characterizing the natural history of ALSP due to CSF1R gene mutations leveraging standardized clinical, imaging and biomarker measurements. The outcome of this study is expected to inform on optimal biomarker and clinical endpoints and design of therapeutic intervention studies in ALSP.