Confirmation of reduced PLP2 transcript and protein in lymphoblasts from unrelated males with XLMR. (A) Northern blot of total RNA from lymphoblast cell lines probed with a human PLP2 cDNA probe that detects an ∼1 kb mRNA. A cDNA probe for human beta-actin (Clontech) hybridized to the same blot provides a loading control. (Lane 1) reference RNA; (lane 2) normal male; (lanes 3–16) unrelated XLMR males. Note reduction of PLP2 mRNA in lanes 8 and 13. Both patients had a substantial reduction of PLP2 mRNA (greater than fourfold) by XCA analysis. (B) Immunoblot of PLP2 in protein lysate (20 μg/lane) from lymphoblasts of the two XLMR probands with reduced levels of PLP2 transcript and two control males. Protein lysate from HEK293 cells transfected with a PLP2–pcDNA3 expression construct was used as positive control (PLP2/293). The 17-kD PLP2 protein is indicated.