MAP2K7 and thanatophoric dysplasia: CNP products in plasma were elevated in skeletal dysplasia with profound short stature due to a disruption of the CNP receptor (NPR-B) (acromesomelic dysplasia type Maroteux), activation of the MEK/ERK MAPK pathway inhibiting NPR-B signaling, activating mutations of FGFR3 (thanatophoric dysplasia, achondroplasia, and hypochondroplasia) [1].