(A) Lymphoblasts from affected individuals showed normal levels of STXPB2 transcript. (B) STXBP2 transcript levels were quantified as the fold difference of mRNA levels for STXBP2 normalized to 18S, a housekeeping gene, in the lymphoblasts from control subjects and patients. Analyses were performed in triplicate. Data are mean ± SD. (C) Left: Western blot showing the expression of STXBP2, STX3, and STX11 proteins in lymphocytes from a healthy control, 3 STXBP2-deficient patients (F2P1, F6P1, and F5P1), and 2 STX11-deficient patients with nonsense mutations in STX11 located in the 5ι (P2) or 3ι (P1) part of the gene. Right: The abundance of STX3 and STX11 (relative to PI3K) via signal intensity measurement. Results are presented as the syntaxin/PI3K ratio, normalized against that obtained with a control (in arbitrary units).