PDE9A and Dravet syndrome: In the analysis of M-PDE9A and U-PDE9A levels according to fetal karyotype, levels of M-PDE9A were not different between the DS cases and controls [1854.3 (interquartile range: 1653.3–2446.3) vs 2004.5 (interquartile range: 1605.2–2316.9)copies/mL, P = 0.928, Fig. 3].