Spastic paraplegia 7 (SPG7) is characterized by insidiously progressive bilateral leg weakness and spasticity. Most affected individuals have decreased vibration sense and cerebellar signs. Onset is mostly in adulthood, although symptoms may start as early as age 11 years and as late as age 72 years. Additional features including ataxia (gait and limbs), spastic dysarthria, dysphagia, pale optic disks, ataxia, nystagmus, strabismus, ptosis, hearing loss, motor and sensory neuropathy, amyotrophy, scoliosis, pes cavus, and urinary sphincter disturbances may be observed.

A rare genetic autosomal recessive spastic ataxia disease with characteristics of the onset in early childhood of spastic paraparesis, cerebellar ataxia, dysarthria and optic atrophy. Caused by homozygous mutation in the MTPAP gene on chromosome 10p11.

SPG53 is an autosomal recessive neurologic disorder characterized by onset in infancy of delayed motor development progressing to upper and lower limb spasticity with impaired walking. Affected individuals also show mild to moderate cognitive impairment (summary by Zivony-Elboum et al., 2012).

Hypomyelinating leukodystrophy-22 (HLD22) is a neurologic disorder characterized by global developmental delay with mildly impaired intellectual development and marked motor impairment with limited or no ability to walk and dysarthria. Affected individuals have limb spasticity with pyramidal signs, as well as nystagmus, hypermetropia, and astigmatism. Brain imaging shows hypomyelination and a delay in myelination, although serial imaging shows some progress in both the central and peripheral white matter regions (Riedhammer et al., 2021). For a general phenotypic description and a discussion of genetic heterogeneity of HLD, see 312080.