An obstetrician will usually diagnose this long before birth with a screening. After birth, there are a number of very visible signs.
- Slanted, almond shaped eyes.
- Decreased muscle tone.
- Extra skin around the neck.
One of the most interesting signs is the simian crease.
It’s a horizontal line in the palm of the hand. Typically we have 2–3 lines:
In an actual palm:
It’s now called a palmar crease because simian refers to monkeys and is seen as demeaning.
And for the record, non-Downs people have this crease as well, but it is far less common. Being in only 1–2 out of 30 people.
It’s still interesting that a fold in the palm is an indicator associated with Downs syndrome. I’ve been searching for the reason “why” it happens but haven’t been able to find the answer.