A method for screening a subject for at least a DNA-damage in relation to a presence of a disease, wherein the method comprises the steps of: - providing carrier plate and a liquid sample; wherein the liquid sample comprises cells of the subject; - providing a gel electrophoresis device, wherein the gel electrophoresis device is capable of: - positioning at least one carrier plate in a homogenous electrical field generated by at least one pair of electrodes; and - controlling strength and direction of the electrical field generated at the position of the samples accommodated on the carrier plate; - performing a single cell gel electrophoresis on the sample of the subject by: - positioning at least one aliquot of the sample having a volume being 15 μL or less and being accommodated on the carrier plate in the generated homogenous electrical field and - controlling strength and direction of the electrical field generated at the position of the aliquot to be constant by maintaining a uniform ion distribution and uniform distribution of constant temperature within the buffer solution while the at least one aliquot of the sample is positioned in the gel electrophoresis device; - using the result of the single cell gel electrophoresis for determining the DNA-damage with coefficient of variation CV of 15% or less, wherein the coefficient of variation is defined as the ratio of the standard deviation to the mean value and is a lab-to-lab, a plate-to-plate or a spot-to-spot coefficient of variation, wherein the liquid sample accommodated on the carrier plate is not flattened and wherein determination of the DNA-damage is performed evaluating 75 to 100 cells per aliquot and using one image per aliquot. - providing carrier plate and a liquid sample; wherein the liquid sample comprises cells of the subject; - providing a gel electrophoresis device, wherein the gel electrophoresis device is capable of: - positioning at least one carrier plate in a homogenous electrical field generated by at least one pair of electrodes; and - controlling strength and direction of the electrical field generated at the position of the samples accommodated on the carrier plate; - positioning at least one carrier plate in a homogenous electrical field generated by at least one pair of electrodes; and - controlling strength and direction of the electrical field generated at the position of the samples accommodated on the carrier plate; - performing a single cell gel electrophoresis on the sample of the subject by: - positioning at least one aliquot of the sample having a volume being 15 μL or less and being accommodated on the carrier plate in the generated homogenous electrical field and - controlling strength and direction of the electrical field generated at the position of the aliquot to be constant by maintaining a uniform ion distribution and uniform distribution of constant temperature within the buffer solution while the at least one aliquot of the sample is positioned in the gel electrophoresis device; - positioning at least one aliquot of the sample having a volume being 15 μL or less and being accommodated on the carrier plate in the generated homogenous electrical field and - controlling strength and direction of the electrical field generated at the position of the aliquot to be constant by maintaining a uniform ion distribution and uniform distribution of constant temperature within the buffer solution while the at least one aliquot of the sample is positioned in the gel electrophoresis device; - using the result of the single cell gel electrophoresis for determining the DNA-damage with coefficient of variation CV of 15% or less, wherein the coefficient of variation is defined as the ratio of the standard deviation to the mean value and is a lab-to-lab, a plate-to-plate or a spot-to-spot coefficient of variation, wherein the liquid sample accommodated on the carrier plate is not flattened and wherein determination of the DNA-damage is performed evaluating 75 to 100 cells per aliquot and using one image per aliquot.