What is (are) Cockayne syndrome ?
Cockayne syndrome is a rare disorder characterized by short stature and an appearance of premature aging. Features of this disorder include a failure to gain weight and grow at the expected rate (failure to thrive), abnormally small head size (microcephaly), and impaired development of the nervous system. Affected individuals have an extreme sensitivity to sunlight (photosensitivity), and even a small amount of sun exposure can cause a sunburn. Other possible signs and symptoms include hearing loss, eye abnormalities, severe tooth decay, bone abnormalities, and changes in the brain that can be seen on brain scans.  Cockayne syndrome can be divided into subtypes, which are distinguished by the severity and age of onset of symptoms. Classical, or type I, Cockayne syndrome is characterized by an onset of symptoms in early childhood (usually after age 1 year). Type II Cockayne syndrome has much more severe symptoms that are apparent at birth (congenital). Type II Cockayne syndrome is sometimes called cerebro-oculo-facio-skeletal (COFS) syndrome or Pena-Shokeir syndrome type II. Type III Cockayne syndrome has the mildest symptoms of the three types and appears later in childhood.