Autosplenectomy is seen in

In sickle cell disease spleen may undergo autoinfarction and is not often palpable beyond 6 years of age. The most frequent cause of autosplenectomy is sickle cell anemia which causes progressive splenic hypofunction over time. Increased deoxygenation causes sickling of red blood cells, which adhere to the spleen wall and splenic macrophages causing ischemia.This ischemia can result in splenic sequestration, where large amounts of blood pool in the spleen but do not flow within vasculature. This lack of blood flow can cause atrophy in the spleen and can lead to autosplenectomy. Reference: GHAI Essential pediatrics, 8th edition