Table 4.

Clinically identifiable disorders with deficient myelination

Disease	Gene	Clinical clues	Neuroimaging findings
Leukodystrophy, hypomyelinating, 1 (Pelizaeus-Merzbacher disease)	PLP1	Developmental delay, hypotonia, rotatory nystagmus	Hypomyelination (FIG 1A) Thinning of corpus callosum
Leukodystrophy, hypomyelinating, 2 (Pelizaeus-Merzbacher like disease 1)	GJC2	Developmental delay, hypotonia, rotatory nystagmus	Hypomyelination Involvement of the corticospinal tracts with abnormal T2-weighted signal extending into the brain stem resulting in extensive brain stem involvement not seen in Pelizaeus-Merzbacher disease Cerebral atrophy at advanced stages
Leukodystrophy, hypomyelinating 5 (Hypomyelination with congenital cataract)	FAM126A	Sudden motor regression Cataract	Hypomyelination (FIG 1A) Cerebral atrophy at advanced stages
Pol III related leukodystrophiesLeukodystrophy, hypomyelinating, 8, with or without oligodontia and/or hypogonadotropic hypogonadism	POLR3B	Hypodontia Hypogonadotropic hypogonadism	Hypomyelination (FIG 1A) Thinning of corpus callosum
Leukodystrophy, hypomyelinating, 7, with or without oligodontia and/or hypogonadotropic hypogonadism	POLR3A	Hypodontia Hypogonadotropic hypogonadism	Hypomyelination (FIG 1A) Thinning of corpus callosum
Ichthyosis, acanthosis nigricans, hypomyelination, spastic paraplegia, high frequency deafness and optic atrophy	ELOVL1	Ichthyosis, acanthosis nigricans, deafness	Hypomyelination
Hypomyelinating neuropathy, congenital, 3	CNTNAP1	Arthrogryposis multiplex congenita	Hypomyelination Thin corpus callosum Cerebellar atrophy Pontine atrophy
Hypermethioninemia with deficiency of S-adenosylhomocysteine hydrolase	AHCY	Facial dysmorphism Abnormal hair and teeth Myocardiopathy Hypermethioninemia	Severely delayed myelination