Fragile sites in human chromosomes I The effect of methionine on the Xq fragile site

Abstract
The Xq fragile site found in males having non-specific X-linked mental retardation was studied by varying the chemical and physical parameters of leukocyte cultures. Methionine was required for marker expression in both medium 199 and MEM [minimal essential medium]. Banding studies indicated that methionine does not function as a stabilizing factor for the fragile site on Xq.