What is (are) X-linked creatine deficiency ?
X-linked creatine deficiency is an inherited disorder that primarily affects the brain. People with this disorder have intellectual disability, which can range from mild to severe, and delayed speech development. Some affected individuals develop behavioral disorders such as attention deficit hyperactivity disorder or autistic behaviors that affect communication and social interaction. They may also experience seizures. Children with X-linked creatine deficiency may experience slow growth and exhibit delayed development of motor skills such as sitting and walking. Affected individuals tend to tire easily.  A small number of people with X-linked creatine deficiency have additional signs and symptoms including abnormal heart rhythms, an unusually small head (microcephaly), or distinctive facial features such as a broad forehead and a flat or sunken appearance of the middle of the face (midface hypoplasia).