Cockayne syndrome

Cockayne syndrome is a rare disease which causes short stature, premature aging (progeria), severe photosensitivity, and moderate to severe learning delay.^[1] This syndrome also includes failure to thrive in the newborn, very small head (microcephaly), and impaired nervous system development. Other symptoms may include hearing loss, tooth decay, vision problems, and bone abnormalities.^[2] There are three subtypes according to the severity of the disease and the onset of the symptoms:^[2][3]

• Cockayne syndrome type 1 (type A), sometimes called “classic” or "moderate" Cockayne syndrome, diagnosed during early childhood
• Cockayne syndrome type 2 (type B), sometimes referred to as the “severe” or "early-onset" type, presenting with growth and developmental abnormalities at birth
• Cockayne syndrome type 3 (type C), a milder form of the disorder 

Cockayne syndrome is caused by mutations in either the ERCC8 (CSA) or ERCC6 (CSB) genes. Inheritance is  autosomal recessive.^[2] Type 2 is the most severe and affected people usually do not survive past childhood. Those with type 3 live into middle adulthood.^[1] There is no cure yet. Treatment is supportive and may include educational programs for developmental delay, physical therapy, gastrostomy tube placement as needed; medications for spasticity and tremor as needed; use of sunscreens and sunglasses; treatment of hearing loss and cataracts; and other forms of treatment, as needed.^[3]

The prognosis for Cockayne syndrome varies by the disease type.^[2] There are three types of Cockayne syndrome according to the severity and onset of the symptoms.However, the differences between the types are not always clear-cut, and some researchers believe the signs and symptoms reflect a spectrum instead of distinct types:^[1][2]    

• Cockayne syndrome Type 1 (type A) is marked by normal development until a child is 1 or 2 years old, at which point growth slows and developmental delays are noticed. Life expectancy for type 1 is approximately 10 to 20 years.
• Cockayne syndrome type 2 (type B), also known as "cerebro-oculo-facio-skeletal (COFS) syndrome" (or "Pena-Shokeir syndrome type II"), is the most severe subtype. Symptoms are present at birth and normal brain development stops after birth. Average lifespan for children with type 2 is up to 7 years of age.
• Cockayne syndrome type 3 (type C) appears later in childhood with milder symptoms than the other types and a slower progression of the disorder. People with this type of Cockayne syndrome live into adulthood, with an average lifespan of 40 to 50 years.