Explanation:
Gaucher disease is an autosomal recessive lysosomal storage disorder caused by a deficiency of the enzyme glucocerebrosidase. This leads to the accumulation of lipid-laden macrophages (Gaucher cells) in the bone marrow. The marrow infiltration causes endosteal scalloping and failure of normal tubulation of the long bones, classically presenting as the 'Erlenmeyer flask' deformity in the distal femurs. Reference: Miller's Review of Orthopaedics, 8th Edition.