Ans. is 'b' Hypothyroidism (Ref. : O.RGhai, 6/e, p 482 (5/e, p447))Presence of mental retardation, growth retardation and wormian bones clinch the diagnosis in favour of hypothyroidism.In Hypothyroidism both mental retardation * and growth retardation * are present andthe skull X-ray shows large fontanelle, wide sutures * and wormian bones *Rickets -Wormian bones are also present in rickets but mental retardation is not seen in ricketsScurvy and Hypoparathyroidism have a radically different symptomatic profile.Important causes of wormian boneHypothyroidism *Hypophosphatasia *Rickets *Cleidocranial dysplasia *Osteogenesis imperfecta *