Absent lateral third of clavicle is seen in

CLEIDOCRANIAL DYSPLASIA/DYSOSTOSIS (CCD)Autosomal recessive disease with faulty intramembranous bone ossificationLarge head with small face, abnormal dentition and drooping hypermobile shouldersRadiological features:Skulla. Platybasia b. Large foramen magnum c. Wormian bonesd. Persistent metopic suture e. 'Hot cross bun' skull f. BrachycephalyThoraxa. Agenesis or hypoplasia of clavicles b. Small winged scapulaePelvisa. Underdeveloped pelvis b. Coxa valgus earlySpinea. Biconvex veebrae b. HemiveebraeExtremitiesElongated 2nd metacarpalD/d: pyknodysostosis (confused with CCD because of similar clavicular and skull changes, and pyknodysostosis is also confused with osteopetrosis because generalized increase in bone density, however these patients are not sho which differentiate it from CCD)