In osteogenesis imperfecta the defect is in the:

Ans; a (Synthesis of type I collagen) Ref: Robbins, ed, p. 1279Osteogenesis imperfecta is due to deficiency in the synthesis of Type I collagen structures affected are - bone, joints,eyes, ear, skin and teethCytogenetic abnormality:Mutation in the genes that codes for a1, and a2 chains of collagen autosomal dominant inheritanceClinical features:All types are characterized by extreme skeletal fragilityOther features are blue sclera, hearing impairment,Dentiogenesis imperfecta, growth retardation etcREMEMBER:Type of osteogenesis imperfecta incompatable with life = type IIType of osteogenesis imperfecta with normal sclera = type IVBRIDGE:Van der hoeve's syndrome - AD osteogenesis imperfecta, blue sclera, hearing loss