Table 1.

Hypomyelinating diseases connected to cholesterol metabolic processes alterations.

Main Events in Cholesterol Metabolism	Defective Protein	Impairment	Hypomyelinating Diseases	References
Synthesis	7-dehydrocholesterol reductase	abnormality in cholesterol production	Smith-Lemli-Opitz syndrome	[26,27]
	acyl-CoA oxidase 1 (ACOX1)	very-long-chain fatty acid (VLCFA) accumulation	Peroxisome biogenesis disorder	[28,29]
	3 b-Hydroxysteroid 8, 7-sterol isomerase	8,9-unsaturated sterols accumulation	Greenberg dysplasia, Conradi–Hunermann syndrome	[30]
Transport	ABCA1 transporter, HDL	No transport out cell	Tangier disease	[31]
	ABCA1, Lrp1	disrupts cholesterol homeostasis	Peroxisome biogenesis disorder	[16,29]
	NPC1, NPC2	defective cellular cholesterol transportation	Niemann–Pick disease C	[26,32]
Accumulation	sterol 27-hydroxylase (CYP27A1)	abnormal cholesterol accumulation	Cerebrotendinous xanthomatosis,	[33,34]
	CYP27A1, Lecithin–cholesterol acyltransferase (LCAT) enzyme, vesicle-associated membrane protein-associated protein B (VapB), and OxySterol Binding Proteins (OSBP)	higher total cholesterol and HDL and LDL levels	Sporadic amyotrophic lateral sclerosis	[35]
	beta-galactosylceramidase	galactosyl-sphingolipids accumulation	Globoid cell leukodystrophy or Krabbe disease	[36]
	arylsulfatase A (ARSA) and Prosaposin precursor (PSAP)	Sulfatides accumulation	Metachromatic leukodystrophy	[37,38]
	PLP1	co-accumulation of PLP and cholesterol	Pelizaeus–Merzbacher disease	[39,40]
	peripheral myelin protein 22 (PMP22)	co-accumulation of apoE, LRP1, and ABCA1	Charcot–Marie–Tooth, Dejerine–Sottas syndrome	[41,42,43]