NPR2 and Acromesomelic dysplasia, Maroteaux type: Second, acromesomelic dysplasia Maroteaux-type (AMDM) was detected in patient K9 with heterozygous missense mutation, R776W, in NPR2. AMDM is a rare autosomal recessive skeletal disorder that leads to severe SS and an abnormal skeletal morphology [26].