What Is Congenital Solitary Kidney?

What Is Congenital Solitary Kidney? Congenital Solitary kidney (CSK) is a disorder caused by the abnormal development of one of the two kidneys. This abnormality can be either anatomical, caused by unilateral renal agenesis (RAG), or functional, caused by extreme forms of dysplasia (renal aplasia-RAP and multicystic dysplastic kidney disease-MCKD). What is a solitary kidney?