TABLE 1.

Identified spastic paraplegia (SPG) genes involved in LD metabolism.

Disease/gene	Protein name	Known molecular function	LD phenotype	Model system
SPG3A/ATL1	Atlastin-1	ER morphogen	Increase in LD number	Astrocytes
			Decrease in LD size	Astrocytes, worms, flies
			Abnormal LD distribution	Worms, flies
SPG4/SPAST	Spastin (M1 and M87 isoforms)	ER morphogen Microtubule severing	Increase in LD number	MEFs, NSC34 cells
			Increase in LD biogenesis	MEFs
			Decrease in LD size	Worms, flies
			Abnormal LD distribution	Zebrafish, MEFs
			LD-peroxisome contacts	Hela cells
SPG11/KIAA1840	Spatacsin	Autophagic lysosomal turnover	Lysosomal turnover of lipids	MEFs, neurons
SPG17/BSCL2	Seipin	LD biogenesis	LD biogenesis, emergence, maturation	Yeast, A431, Drosophila S2, SUM 159, and Hela cells
			LD detachment	A431 cells
SPG18/ERLIN2	ERLIN2	ER-associated degradation	LD accumulation	Hela cells
SPG20/SPART	Spartin	Endosomal trafficking	LD turnover	HEK 293T, Hela cells
			LD accumulation	HEK 293T, Adipose tissue, MEFs
SPG31/REEP1	REEP1	ER morphogenesis	Decrease in LD number and size	MEFs
			Decrease in LD number	Neurons, adipocytes
SPG54/DDHD2	Phospholipase A1	Phospholipase, TAG lipase in the brain	LD accumulation	Mouse brain and spinal cord
			Peroxidized lipid accumulation	MEFs
SPG62/ERLIN1	ERLIN1	ER-associated degradation	LD accumulation	Hela cells
SPG73/CPT1C	CPT1C	Binding malonyl-CoA	Decrease in LD number	Neurons
BICD2	BICD2	Dynein-mediated motility	LD movement	Fly embryos