Mental Retardation With Spastic Paraplegia And Palmoplantar Hyperkeratosis

Clinical Features

Fitzsimmons et al. (1983) reported mental retardation with spastic paraplegia and palmoplantar hyperkeratosis in 4 brothers whose ages ranged from 16 to 35 years at the time of report. Pes cavus was striking. The mother was of normal intelligence but had plantar hyperkeratosis and a strong facial resemblance to her retarded sons. Her 3 daughters, aged 28 to 34 years, were normal.

Isidor et al. (2013) reported 2 maternal half brothers with palmoplantar hyperkeratosis, mild intellectual disability, and brisk reflexes and hypertonia in the lower limbs consistent with spastic paraplegia. Both boys also had tremors in the upper limbs and one had bilateral pes cavus deformity. The boys' mother had a normal dermatologic examination and no motor disabilities. On neurologic examination, she had brisk reflexes, left Babinski sign, and a postural hand tremor. She had moderate school learning difficulties. Analysis at the FMR1 locus (309550) suggested skewing of the X-inactivation pattern, although the skewing was incomplete (less than 95%). The fathers of the half brothers were not related.

Inheritance

The transmission pattern of mental retardation with spastic paraplegia and palmoplantar hyperkeratosis in the families reported by Fitzsimmons et al. (1983) and Isidor et al. (2013) supports X-linked recessive inheritance of the disorder.