MTHFR and hereditary spastic paraplegia: A total of 28 positive cases were identified, including 15 cases of HSP, five cases of Hcy remethylation disorders (methylmalonic acidemia/MMA and methylenetetrahydrofolate reductase/MTHFR deficiency), five cases of LD (cerebrotendinous xanthomatosis/CTX, X-ALD, Krabbe’s disease and hypomyelination leukodystrophy-7/HLD7), two cases of HA (autosomal recessive cerebellar ataxia type 8/SCAR8 and autosomal recessive spastic ataxia of Charlevoix-Saguenay/ARSACS), and one case of CMT.