MedGen

Hereditary sensory and autonomic neuropathy type II (HSAN2) is characterized by progressively reduced sensation to pain, temperature, and touch. Onset can be at birth and is often before puberty. The sensory deficit is predominantly distal with the lower limbs more severely affected than the upper limbs. Over time sensory function becomes severely reduced. Unnoticed injuries and neuropathic skin promote ulcerations and infections that result in spontaneous amputation of digits or the need for surgical amputation. Osteomyelitis is common. Painless fractures can complicate the disease. Autonomic disturbances are variable and can include hyperhidrosis, tonic pupils, and urinary incontinence in those with more advanced disease. [from GeneReviews]

Autosomal recessive spastic paraplegia-78 is an adult-onset neurodegenerative disorder characterized predominantly by spasticity and muscle weakness of the lower limbs, resulting in gait difficulties and loss of ambulation in some patients. Affected individuals also have cerebellar signs, such as dysarthria, oculomotor disturbances, and limb and gait ataxia; brain imaging shows cerebellar atrophy. Some patients may have mild cognitive impairment or frank dementia. The phenotype is highly variable (summary by Estrada-Cuzcano et al., 2017). Biallelic mutation in the ATP13A2 gene also causes Kufor-Rakeb syndrome (KRS; 606693), a neurodegenerative disorder with overlapping features. Patients with KRS have earlier onset and prominent parkinsonism. Loss of ATP13A2 function results in a multidimensional spectrum of neurologic features reflecting various regions of the brain and nervous system, including cortical, pyramidal, extrapyramidal, brainstem, cerebellar, and peripheral (summary by Estrada-Cuzcano et al., 2017). [from OMIM]

NARS1-related neurologic disorders encompass NARS1-related neurodevelopmental disorder (NARS1-NDD), a neonatal- or childhood-onset phenotype with central nervous system and peripheral nervous system involvement, and NARS1-related hereditary neuropathy, an adolescent- or early adult-onset hereditary neuropathy. NARS1-NDD manifests with global developmental delay, intellectual disability, microcephaly, ataxia, seizures, and, rarely, neurobehavioral/psychiatric manifestations. Change in muscle tone can manifest either as spasticity or as hypotonia. Peripheral neuropathy with atrophy predominantly of the distal lower limbs can be associated. NARS1-related hereditary neuropathy manifests with mostly motor and sensory impairment involving weakness of predominantly the distal lower limbs and foot deformities, without prominent muscle atrophy. A few individuals have been described with isolated hereditary motor neuropathy associated with foot deformities, ankle contractures, kyphosis, hyperlaxity, and brisk reflexes. To date, 54 individuals from 30 families with NARS1 pathogenic variant(s) have been reported. [from GeneReviews]

NARS1-related neurologic disorders encompass NARS1-related neurodevelopmental disorder (NARS1-NDD), a neonatal- or childhood-onset phenotype with central nervous system and peripheral nervous system involvement, and NARS1-related hereditary neuropathy, an adolescent- or early adult-onset hereditary neuropathy. NARS1-NDD manifests with global developmental delay, intellectual disability, microcephaly, ataxia, seizures, and, rarely, neurobehavioral/psychiatric manifestations. Change in muscle tone can manifest either as spasticity or as hypotonia. Peripheral neuropathy with atrophy predominantly of the distal lower limbs can be associated. NARS1-related hereditary neuropathy manifests with mostly motor and sensory impairment involving weakness of predominantly the distal lower limbs and foot deformities, without prominent muscle atrophy. A few individuals have been described with isolated hereditary motor neuropathy associated with foot deformities, ankle contractures, kyphosis, hyperlaxity, and brisk reflexes. To date, 54 individuals from 30 families with NARS1 pathogenic variant(s) have been reported. [from GeneReviews]

Autosomal recessive spastic paraplegia-85 (SPG85) is a neurologic disorder characterized by the onset of motor symptoms in the first few years of life. Affected individuals have spasticity and hyperreflexia of the lower limbs resulting in gait abnormalities. Older patients may have upper limb involvement and demonstrate axonal polyneuropathy. Additional features include optic atrophy, dysarthria, dysphagia, ataxia, and urinary incontinence. Brain imaging may show cerebellar atrophy (summary by Wagner et al., 2019). For a discussion of genetic heterogeneity of autosomal recessive spastic paraplegia, see SPG5A (270800). [from OMIM]

Autosomal recessive distal hereditary motor neuronopathy-7 (HMNR7) is characterized by onset of lower leg weakness in the first decade. Affected individuals have difficulty climbing stairs and problems standing on the heels. Some patients have later onset well into the adult years. Most patients have foot deformities, and some may have leg muscle atrophy. The disorder is slowly progressive and often involves the upper limbs. Muscle biopsy and electrophysiologic studies are consistent with both a myopathic process and an axonal motor neuropathy. Sensory abnormalities are not typically present, and patients remain ambulatory. The phenotype shows phenotypic overlap with distal hereditary motor neuropathy, but can distinguished by the presence of myopathic features (summary by Deschauer et al., 2021 and Pagnamenta et al., 2021). For a discussion of genetic heterogeneity of autosomal recessive HMN, see HMNR1 (604320). [from OMIM]

A reduced sense of touch (tactile sensation). This is usually tested with a wisp of cotton or a fine camel's hair brush, by asking patients to say 'now' each time they feel the stimulus. [from HPO]