Galactokinase deficiency (GALK), a mild type of galactosemia, is an inherited disorder that impairs the body's ability to process and produce energy from a simple sugar called galactose. If babies with GALK eat foods containing galactose, undigested sugars build up in the blood. Galactose is present in many foods, including all dairy products, many baby formulas, and some fruits and vegetables. Rarely, a child with GALK will have pseudotumor cerebri, a condition which mimics the symptoms of a large brain tumor when no brain tumor is present. This is thought to be caused by increased pressure in the brain from cerebrospinal fluid (CSF) due to elevated levels of a galactose product in the CSF. The serious medical problems that occur with "classic" galactosemia (type 1), such as liver, kidney, and brain damage, typically are not present in people with GALK. GALK is caused by genetic changes in the GALK1 gene and inheritance is autosomal recessive. The disorder may be suspected in babies with an abnormal newborn screening result, or in babies with cataracts. The diagnosis can be confirmed with biochemical and molecular genetic testing.