Restless legs syndrome (RLS) is a neurologic sleep/wake disorder characterized by uncomfortable and unpleasant sensations in the legs that appear at rest, usually at night, inducing an irresistible desire to move the legs. The disorder results in nocturnal insomnia and chronic sleep deprivation (Bonati et al., 2003). Genetic Heterogeneity of Restless Legs Syndrome RLS1 has been mapped to chromosome 12q. Other susceptibility loci for RLS include RLS2 (608831) on chromosome 14q13-q31; RLS3 (610438) on chromosome 9p24-p22; RLS4 (610439) on chromosome 2q33; RLS5 (611242) on chromosome 20p13; RLS6 (611185) on chromosome 6p21; RLS7 (612853) on chromosome 2p14; and RLS8 (615197) on chromosome 5q31.

A rare genetic haematologic disease characterised by decreased or undetectable serum L-ferritin with otherwise normal laboratory parameters. Clinical signs and symptoms include generalised seizures, atypical restless leg syndrome, mild neuropsychologic impairment and progressive hair loss. Asymptomatic cases have also been reported.

Any Parkinson disease in which the cause of the disease is a mutation in the CHCHD2 gene.

Parkinson disease-25 (PARK25) is a progressive neurodegenerative disorder characterized by onset of parkinsonism in late childhood/adolescence and developmental delay/impaired intellectual development. Cognitive impairment is mild to moderate and nonprogressive (Fevga et al., 2023). For a general phenotypic description and a discussion of genetic heterogeneity of Parkinson disease, see 168600.

Autosomal dominant distal hereditary motor neuronopathy-11 (HMND11) is a peripheral axonal motor neuropathy characterized by juvenile or young-adult onset of distal limb muscle weakness and atrophy mainly affecting the lower limbs, resulting in gait instability and walking difficulties. Foot deformities may also be present. The disorder is usually slowly progressive, and patients remain ambulatory until late adulthood. Some affected individuals may have distal upper limb and hand involvement or mild distal sensory abnormalities, but motor symptoms dominate the clinical picture. Electrophysiologic studies are consistent with a length-dependent axonal motor or sensorimotor neuropathy. Seizures are not present and brain imaging is normal (Beijer et al., 2019). One reported affected individual had a marfanoid habitus and mild speech delay with learning disabilities, suggesting possible expansion of the phenotypic spectrum (Ylikallio et al., 2020). For a discussion of genetic heterogeneity of autosomal dominant distal HMN, see HMND1 (182960).