You may want to talk to your Dr(s) about Lysosomal Storage Disorders that can cause damage to the nervous system. There are a number of them and most are considered rare, but I suspect not as rare as most Drs think...just "missed".
I had some genetic testing done and am scheduled to see a Geneticist later this month. The testing I've had done shows potentially pathogenic variants in the following genes:
ASAH1 which is linked to Hereditary Sensory and Autonomic Neuropathy
GBA, GBAP1 which are linked to Gaucher's Disease
PPT1 - which is linked to Neuronal Ceroid Lipofuscinosis/Batten/Kuf's Disease
My rudimentary understanding is that the genetic variant causes an error in the creation of certain proteins, which makes them unusable for their original purpose, and the degradation of the errant protein causes neurological damage. In general, treatment includes Enzyme Replacement Therapy, Substrate Reduction, dietary changes and in some cases high doses of specific amino acids to try to block substitution of the incorrect amino acid in building the affected protein.
Many Lysosomal Storage Disorders are symptomatic at birth, other can present later...including adult onset in some cases. Symptoms are many and can vary in severity.
https://www.webmd.com/children/what-are-lysosomal-storage-disorders
https://medlineplus.gov/genetics/gene/asah1/
L-Serine Study Results
https://deaterfoundation.org/l-serine-study-results/
Neurological manifestations of lysosomal storage diseases https://pmc.ncbi.nlm.nih.gov/articles/PMC11543150/