A 2- year-old boy presented with failure to thrive, rgression of developmental milestone

(E). Niemann-pick disease (NPD), inherited as autosomal recessive traits, the clinical manifestations and course of type A NPD is uniform and is characterized by a normal appearance at birth. Hepatosplenomegaly, moderate lymphadenopathy, and psychomotor retardation are evident by 6 mo of age, followed by neurodevelopmental regression and death by 3 yr. With advancing age, the loss of motor function and the deterioration of intellectual capabilities are progressively debilitating; and in later stages, spasticity and rigidity are evident. Affected infants lose contact with their environment. Type B disease is a non-neuronopathic form observed in children and adults NPD types A and B result from the deficient activity of acid sphingomyelinase. Type C disease is a neuronopathic form that results from defective cholesterol transport