I think I know what she's talking about & nothing on your link applies.
It's a hereditary thing you inherit that gets worse with each generation & each person in the family who has it has it on the same fingers, which is usually only one finger, maybe one on each hand.
It only applies to the free edge part of the nail. The nail grows normally, then a few millimeters away the nail starts to curve downwards. As it grows longer, it starts to spiral like a corkscrew. If it gets long enough without breaking, the fingernail will appear to be growing upside down at a point before it twists again. Clipped short, the nail looks like the roof of a house or home plate.View Thread