Snyder-Robinson syndrome

Snyder-Robinson syndrome is an x-linked recessive disorder. It is associated with moderate mental retardation, asthenic body build-up, hypotonia, gait, osteoporosis, kyphoscoliosis, and facial asymmetry, and manifests in childhood or adolescence. Most of the time, there is already a developmental delay in early childhood due to the delayed achievement of early milestones in development. Later on, there is a moderate to severe global mental disability and varying degrees of motor disability.

The asthenic habit associated with low muscle mass usually manifests itself in the first year of life. In the first decade, patients develop osteoporosis, leading to fractures without appropriate trauma.

In the affected patients, there is a mutation in the SMS gene, which is located in the chromosome region Xp22.1 and encodes spermine synthase.