I'll start by saying that my dc3 has a birth defect (chromosomal) that means he is fairly disabled. It shares a lot of overlapping characteristics with DS (learning disabilities, cardiac problems, developmental delays etc) so I follow a lot of people on SM who have children with DS.
The WHO have included DS as a birth defect (alongside spina bifida, CHD) and there has been quite an uproar and "much disappointment at WHO". As a parent with a child with a birth defect I get the label hurts when it is written down like that, and my ds' disabilities are not his definition by any means. BUT, he still has a birth defect by definition, and no amount of flowery language is going to change his health problems and long term need for care.
I posted in AIBU for traffic, but it would be interesting to engage in discussion about why some people feel DS isn't a 'birth defect' but are fine with other birth diagnoses (for want of a better word) to be defects or disabilities?