How does SID overlap with Down syndrome?

How does SID overlap with Down syndrome?

Signs of sensory processing problems of a child with DS are often
similar to that of a child traditionally labeled with sensory
integration dysfunction:

Delays in speech, language and motor skills
Delays in learning
Poor self-concept
Poor self-control (impulsive)
Low muscle tone
Poor body awareness
Over reaction to touch, sound, sight, movement (avoids)
Under reaction to touch, sound, sight, movement (seeks)
Resistance to change
Poor transitions
Poor social skills
Poor balance
Clumsy/awkward movement
Unusually high or low activity level
Poor behavior organization

Children with DS often exhibit characteristics which impact motor
skills such as hypotonia (low muscle tone), joint laxity, difficulty
sensing joint position and movement, hypo or hyper responsivity to
touch, discrimination, and integration of touch input. The motor
performance and behaviors of a child with DS can also be impacted by
sensory processing deficits including deficits in sensory
registration, modulation, vestibular, proprioceptive, tactile, visual,
and auditory processing.

http://www.ndsccenter.org/resources/documents/sensoryIntegration.php