Heritable fragile sites on human chromosomes. X. New folate-sensitive fragile sites: 6p23, 9p21, 9q32, and 11q23.

Four new folate-sensitive fragile sites are documented at 6p23, 9p21, 9q32, and 11q23. These have all been shown to be heritable except for the one at 9p21, which has been seen only in a single individual. As with the other autosomal fragile sites, these appear to be innocuous in heterozygotes.