Each lesion—a damaged section of DNA—must be snipped out and the DNA repaired to preserve its normal function. Unrepaired DNA can lose its ability to code for proteins. Mutations also can result. These mutations can activate oncogenes or silence tumor suppressor genes. According to research, oxidative damage to active genes is not preferentially repaired, and in the most severe cases, the repair is slowed throughout the whole genome. The resulting accumulation of oxidative damage could impair the normal functions of the DNA and may even result in triggering a program of cell death (apoptosis). The children with this disease do not repair the active genes where oxidative damage occurs. Normally, oxidative damage repair is faster in the active genes (which make up less than five percent of the genome) than in inactive regions of the DNA. The resulting accumulation of oxidative damage could impair the normal functions of the DNA and may even result in triggering a program of cell death (apoptosis). Genetics
Cockayne syndrome is classified genetically as follows:
Mutations in the ERCC8 (also known as CSA) gene or the ERCC6 (also known as CSB) gene are the cause of Cockayne syndrome. Mutations in the ERCC6 gene mutation makes up ~70% of cases. The proteins made by these genes are involved in repairing damaged DNA via the  transcription-coupled repair mechanism, particularly the DNA in active genes. DNA damage is caused by ultraviolet rays from sunlight, radiation, or free radicals in the body. A normal cell can repair DNA damage before it accumulates.
A quadricuspid aortic valve (QAV) is a rare congenital heart defect characterized by the presence of four cusps, instead of the usual three found normally in the aortic valve. It is a defect that occurs during embryological development of the aortic trunk during gestation. There is an increased risk of developing post-natal aortic regurgitations and other heart-related diseases; therefore patients with the condition should be carefully monitored. Signs and symptoms
Complications
The most common complications of QAV are aortic regurgitations. This is caused by the inadequate closing of the four cusps at the end of systole. The fourth dysplastic cusp is incapable of fully closing the aortic annulus, which causes a backflow of blood through the aortic valve. Using transthoracic echocardiograms, 3-D TEE and ECG traces, it is also possible to find left ventricular hypertrophy, bundle branch blocks, and abnormal displacement of the ostium in the right coronary artery in association with QAV. Some research has shown increased incidences of atrial fibrillation to be associated but this relationship is not yet clearly established. Diagnosis
Previously, diagnosis was usually done through autopsy. Advances in imaging technologies allow for early detection and thus ample treatment and monitoring of the affected patient. A short-axis ultrasound of the aortic valve allows for the best view of the aortic valve, and gives a clear indication of the adduction pattern of the aortic valves.If an “X” shape is seen, then the patient can be diagnosed with having a quadricuspid aortic valve.