What is the risk of a trisomy 21 parent passing on the condition to his/her offspring? should adults with down syndrome be dissuaded from reproducing

It happends: Males with Down syndrome are essentially sterile.A few rare mosaic male down cases might be capable but this the exception. Females have a 50% risk of passing ds to an offspring, but actual outcome is a bit >50% normal because some ds pregnancies will terminate spontaneously. A simple plan for long term birth prevention is an important feature in ds care. Ob + pcp+ family discussion is needed early.

Depends on type: Risk to offspring depends on parents inheritence pattern.