X-linked dominant chondrodysplasia punctata 2, also known as Conradi-Hünermann-Happle syndrome, is a rare form of skeletal dysplasia that affects the skeleton producing short stature, asymmetric shortening of the limbs and scoliosis, as well as affecting the skin, hair and eyes. X-linked dominant chondrodysplasia punctata 2 is presumed lethal in males, although a few affected males have been reported. Patients with X-linked dominant chondrodysplasia punctata 2 display skin defects including linear or whorled atrophic and pigmentary lesions, striated hyperkeratosis, coarse lusterless hair and alopecia, cataracts, and skeletal abnormalities including short stature, rhizomelic shortening of the limbs, epiphyseal stippling, and craniofacial defects. Affected patients require dermatological care, as regular emollient application improves skin scaliness. Scoliosis and limb asymmetry lead to premature arthritis, requiring orthopaedic input.

X-linked dominant chondrodysplasia punctata 2 is due to mutations affecting a delta8-delta7 sterol isomerase (EBP, emopamil binding protein, at Xp11.22-p11.23) that functions downstream of NAD(P)H steroid dehydrogenase-like protein (NSDHL) gene in the cholesterol biosynthesis pathway catalyzing the conversion of 8(9)-cholestenol to lathosterol.