How often does talipes (club foot) with sandal gap in a fetus indicate some kind of chromosomal disorder?

Up to 33%: Fetal talipes equinovarus with or without sandal gap may be associated with a chromosomal abnormality as often as 33% of times, and when associated, other abnormalities are found. The most common association is with trisomy 18 (having an extra chromosome #18). In one study only 22% had isolated talipes.

30%: Club foot with or without a sandal gap is associated with chromosomal abnormalities as much as 30 % of the time.