He appears to have a rather mild form of down syndrome.

Now - Down Syndrome is typically called trisomy 21, that is, you have three copies of chromosome 21 when normally people have two copies of each chromosome, excluding XY in regular males (2n = 46 in humans, the diploid state; naturally females would have XX, whereas humans would normally have XY, unless there would be a genetic change leading to a different ploidy state here as well; normally those with Down Syndrome have regular XX or XY condition for that chromosome, only chromosome 21 has a +1 higher count). If you, however had, look at as many examples as possible for people with Down Syndrome, you notice a huge range of differences here. That is, some are affected by the condition a LOT; others have an almost normal life, compared to perhaps average to a bit below average "regular" humans. I also noticed something similar for the progeria disease. Now, progeria is much more problematic and severe than Down syndrome; but there is a huge range of people with different symptoms here. Adalia Rose had a severe variant and did not survive past age 15, whereas Tiffany Wedekind has a less severe variant (but also exercises a lot and tries to keep healthy, despite already facing significant health problems, at age 48 this year now).

So we see a huge pleiotropy of different genetic conditions. In most cases exercises, activity and mental mood improves things, but there are hard caps and limits. For instance, Adalia could not have done as Tiffany did, simply due the genetic status being different. It reminds me of the movie Gattaca (now almost 30 years old) - it's a bit slow and a bit over-drama, but has great actors and an even greater take-home message aka "The Underdog who never gives up". Good to have seen it at the least once, too.