Cystinuria is an inherited disease that causes stones made of
the amino acid cysteine to form in the kidneys, bladder, and
urethra. Inherited means that the disease is passed down from
parents to children through a defect in their genes. In order to
get cystinuria, a person must inherit the defect from both
parents. The defect in the gene causes cysteine to accumulate
inside the kidneys—organs that help regulate what goes in and
out of your bloodstream. The kidneys have many functions,
including reabsorbing essential minerals and proteins back into
the body, filtering the blood to remove toxic waste and
producing urine so that you can excrete the waste out of the
body. Instead of going back into the bloodstream, the amino acid
cysteine builds up and forms stones. The stones can then get
stuck in the kidneys, bladder, and urethra (the tube that
carries urine out of the body). This can be very painful until
the stones pass through urination. Very large stones may need to
be surgically removed. The stones can re