Developmental Language Disorder Awareness Day

Let's see...DLD is language difficulty (speaking and understanding, relative to age) which is _not_ a concomitant of some other difficulty (e.g. hearing loss, autism spectrum disorder).
Crystal relates that it has long been recognized by speech/language therapists and the like, but not until 2016 did they get together and agree on a standard name for it. To them we owe this day.
So it's a thing, it has a name, but given the negative definition above, one wonders whether they have made a good case that it is just one thing.
There's more on it out there:
https://www.nidcd.nih.gov/sites/default/files/Documents/health/voice/developmental-language-disorder.pdf
https://www.deb.co.nz/dyslexia/getting-started/what-is-developmental-language-disorder-dld/
https://speechandlanguage.org.uk/educators-and-professionals/resource-library-for-educators/developmental-language-disorder-dld/
I seem to remember from years ago that DLD played a role in arguments about the evolution of language, since it was claimed to be associated with the presence or absence of a particular gene. Don't know whether this is still taken seriously.