To respond to the OP's question, astrologically all I can say is that nearly every case of innate severe physical deformities or extreme issues like Down Syndrome I see, there are often really horrific degrees and stars associated with violence on the angles (Ascendant, Imum Coeli, Descendant, Midheaven). Especially 15 and 25 degrees Leo/Aquarius. That doesn't mean everyone with those malefic things on their angles are born with disability (sometimes they are normal but have alcoholism, awful relationships, bad background or something) but there is a trend there.
Plus bad angles in cases of severe disability it is very common for the Sun to combust other planets (especially the Chart Ruler), the Chart Ruler being on a bad degree, and Saturn and the outer planets residing on those angles. Pluto (has something to do with the lips in tandem with Mars) being in close proximity to angles on bad degrees tends to implicate Cleft Palate issues, for example.
Things like Saturn in 3rd tend to denote more minor issues than that like a stutter unless the rest of the chart is really bad.
In any case I wonder about the connection of extreme violence and disability because of things like this showing up in charts. Probably it has something to do with slavery and lives going on a downward trend, but maybe these people have been born disabled over and over for a while.