Neurological examination showed mild diffuse muscle hypotonia, hypotrophy, mild diffuse muscle weakness, joint laxity, scapular winging and increase of lumbar lordosis. [kundoc.com]

Systemic Features: Males have mild to moderate mental retardation, muscle hypotonia and weakness with postural tremor. Their standing position is broad-based and they are unable to sit or stand otherwise without some support. [disorders.eyes.arizona.edu]

behavior Cognitive delay Intellectual disability Microcephaly Poor speech Abnormality of the skeletal system Microcephaly ... ... [familydiagnosis.com]

[…] dysarthria, nystagmus; partial complex and generalized motor seizures; polyneuropathy; genetic testing available SCA11 (autosomal dominant type 11) 15q14-q21.3 by linkage Slowly progressive gait and extremity ataxia, dysarthria, vertical nystagmus, hyperreflexia [accessmedicine.mhmedical.com]

[…] metacarpophalangeal joint; [Feet]; Pes cavus; Slender feet SKIN, NAILS, HAIR: [Hair]; Central balding; Sparse hair MUSCLE, SOFT TISSUE: Muscle atrophy affecting the upper back and neck muscles NEUROLOGIC: [Central nervous system]; Mental retardation ; Hyperreflexia [findzebra.com]

It was described in 1934 by Folling in 10 children with ID, hypertonia, and hyperreflexia, with a musty odor in urine and sweat. Seizures and tremors are common, as are eczema and psychotic manifestations. [emedicine.medscape.com]