A new inducible fragile site on chromosome 3(p14.2) in human lymphocytes.

A fragile site on chromosome 3(p14.2) was found in lymphocytes of two unrelated patients. Expression of the trait with 6%-18% affected cells could only be demonstrated under culture conditions favouring a low concentration of folic acid. Family investigations proved the maternal transmission of the cytologic marker in one case. In contrast to other fragile sites chromatid type aberrations predominated.