Snyder-Robinson Syndrome (SRS) is an ultrarare genetic disorder that affects males. SRS is characterized by intellectual disability, muscle and bone abnormalities, developmental delays, and sometimes other medical problems.
Individuals with SRS have various degrees of delayed development in the areas of speech, motor and cognitive skills. These delays are usually evident in early childhood. Some are mildly affected, and others require a significant level of care.
Most people with SRS are thin and have low muscle mass. Low muscle tone (hypotonia) is typically apparent in infancy, and the loss of muscle mass usually progresses with age. People with SRS often have difficulty walking, and some are not able to walk at all. Of those people who develop the ability to walk, most have an unsteady gait or require assistance.
SRS causes skeletal problems, particularly thinning of the bones (osteoporosis) that starts in early childhood. Osteoporosis causes bones to be brittle and to break easily, often during normal activities and in the absence of trauma. In people with SRS, broken bones occur most often in the long bones of the arms and legs. Most affected individuals also develop an abnormal side-to-side (scoliosis) and back-to-front curvature of the spine (kyphosis), often called kyphoscoliosis when they occur together.
SRS is also associated with distinctive facial features, including a prominent lower lip; a high, narrow roof of the mouth or an opening in the roof of the mouth (a cleft palate); and differences in the size and shape of the right and left sides of the face (facial asymmetry). Other findings may include neurological problems, seizures, and other abnormalities which are described here.