d e f g h i j k l m n o p q r s t u v w x y z x x chromosome x marks the spot x out x pr x'd x-axis x-c x-chromosome x-disease x-ed x-height x-inactivation x-irradiate x-line x-linked x-linked gene x-linked hypogammaglobulinemia x-linked hypophosphatemic osteomalacia x-radiate x-radiation x-rated x-ray...