Spastic Diplegia And Mental Retardation

Clinical Features

Hanhart (1936) described 7 cases of infantile spastic diplegia in 4 related sibships. All 8 parents could be traced to a common ancestor born in the 17th century. Penrose (1963) observed the disorder with mental retardation in 2 offspring of a first-cousin marriage.

In a geographically isolated northern Swedish population, Book (1956) and Book and Sjogren (1970) identified several individuals with spastic diplegia associated with varying degrees of mental retardation. Gustavson et al. (1987) performed a follow-up investigation of 24 patients with hereditary spasticity originally examined by Book (1956) and identified 5 new cases of spastic syndromes diagnosed in this population. Three of the 5 new cases were described as having a progressive spinocerebellar degeneration syndrome, which started in the first years of life with ataxia, followed by dysarthria, spasticity, and jerky intention tremor. The patients had mild mental retardation. Gustavson et al. (1989) described affected brother and sister from the same population who were followed from infancy. Both had spastic diplegia with hypotonia and mental retardation. The 17-year-old brother was able to walk unsupported, and the 4-year-old sister was able to walk with support. Gustavson et al. (1989) referred to the disorder as Book syndrome, a designation that has been applied to a different disorder (112300).

Inheritance

Gustavson et al. (1989) reported a brother and sister with progressive spinocerebellar degeneration who were born to consanguineous healthy parents, supporting autosomal recessive inheritance.

Population Genetics

Book (1956) reported an incidence of 2.6 per 1,000 births of a spastic diplegia syndrome associated with varying degrees of mental retardation in a geographically isolated population of northern Sweden.