Cells strains were collected from patients who were photosensitive due to Cockayne's Syndrome (CS) or trichothiodystrophy (TTD). Post ultraviolet (UV) ribonucleic acid (RNA) synthesis was reduced in GS. From questionnaries completed by clinicians it was seen that other indicators of CS are pigmentary retinopathy, gait defects and dental caries. Complementation analysis was carried out using 3 known complementation groups but no new complementation groups have been discovered. TTD cell strains were examined for repair synthesis and cell survivial following UV irradiation. Type 1 showed a normal response; type 2 was deficient in excision and repair of UV damage and did not complement xeroderma pigmentosum (XP) cell strains in complementation group D; type 3 has a specific deficiency in the repair of 6-4 photoproducts; this suggests DNA repair defects are in 3 different genes associated with TTD.
Cockayne's Syndrome (CS) and trichothiodystrophy (TTD) are
sun-sensitive disorders associated with deficiencies in the repair of cellular DNA.
In CS strains RNA synthesis fails to recover after UV-irradiation. RNA synthesis after UV-irradiation will be measured in CS cell strains established from a large number of patients. Cultures of pairs of cells will be fused together and RNA synthesis measured in the binucleate heterokaryons. All CS strains can then be assigned to different complementation groups and the genetic complexity of CS can be established.
TTD cells are deficient in excision-repair. The genetic complexity of TTD can be measured using similar procedures but using excision-repair as the end-point.
Funding SchemeCSC - Cost-sharing contracts