Cockayne syndrome

Cockayne syndrome (also called Weber-Cockayne syndrome, or Neill-Dingwall Syndrome) is a rare autosomal recessive congenital disorder characterized by growth failure, impaired development of the nervous system, abnormal sensitivity to sunlight (photosensitivity), and premature aging. Hearing loss and eye abnormalities (pigmentary retinopathy) are other common features, but problems with any or all of the internal organs are possible. It is associated with a group of disorders called leukodystrophies. The underlying disorder is a defect in a DNA repair mechanism.

It is named after English physician Edward Alfred Cockayne (1880–1956). Neill-Dingwall syndrome was named after Mary M. Dingwall and Catherine A. Neill.

Forms of Cockayne syndrome

 * CS Type I, the classic form, is characterized by normal fetal growth with the onset of abnormalities in the first two years of life. Impairment of vision, hearing, and the central and peripheral nervous system progressively degenerate until death in the first or second decade of life.
 * CS Type II, otherwise known as connatal CS, involves very little neurological development after birth. Death usually occurs by age 7. This specific type has also been designated as cerebro-oculo-facio-skeletal (COFS) syndrome. Having said that, COFS syndrome itself is subdivided into several conditions (COFS type 1, 2, 3 (which is itself is associated with Xeroderma Pigmentosum) and type 4).
 * CS Type III is rare and is characterized by late onset. It is milder than Type I and II.
 * Xeroderma-pigmentosum-Cockayne syndrome (XP-CS) occurs when an individual also suffers from Xeroderma pigmentosum, another DNA repair disease. Some symptoms of each disease are expressed.

Genetics
Cockayne syndrome is classified genetically as follows:

Mutations in the ERCC6 and ERCC8 genes are the cause of Cockayne syndrome. The proteins made by these genes are involved in repairing damaged DNA via the transcription-coupled repair mechanism, particularly the DNA in active genes. If either the ERCC6 or the ERCC8 gene is altered, DNA damage is not repaired. As this damage accumulates, it can lead to malfunctioning cells or cell death.

Mutations in the ERCC6 gene mutation makes up ~70% of cases.

Physical appearance
Small head size, short stature, sunken eyes, "aged" look.