Prosopagnosia is the inability to recognize someone by the face alone, in the absence of sensory or intellectual impairment (Schwarzer et al., 2007). Almost all reported cases are of the acquired form, but there is evidence for a familial form as well (McConachie, 1976; de Haan, 1999; Galaburda and Duchaine, 2003; Kennerknecht et al., 2006).

Hypomyelinating leukodystrophy-15 (HLD15) is an autosomal recessive neurodegenerative disorder characterized by onset of motor and cognitive impairment in the first or second decade of life. Features include dystonia, ataxia, spasticity, and dysphagia. Most patients develop severe optic atrophy, and some have hearing loss. Brain imaging shows hypomyelinating leukodystrophy with thin corpus callosum. The severity of the disorder is variable (summary by Mendes et al., 2018) For a discussion of genetic heterogeneity of HLD, see 312080.