[Sex determination at the DNA level. Are inter-individual differences in male sex specific quotients to be expected?].

A determination of sex was performed for 23 male individuals using sex-specific DNA-probe (Y) (pJA 1143) and total human DNA as DNA-probes (A). The DNA-probes were P32 marked. Applying dot-blot-hybridisation black spots are obtained, the intensity of which may be quantified by a densimeter. The ratio (A/Y) of the intensity of the spots related to total human DNA (A) and to the sex-specific DNA-probe (Y) was calculated. DNA-dilutions of one male individual were prepared in order to determine the ratio (A/Y) for different DNA-concentrations. It was evident that the deviations for the sex-specific quotients of the DNA-dilutions amounts so large-scaled as compared to the quotients of the 23 male individuals, that the method of dot-blot-hybridisation appears not to be applicable to detect an individual component of a particular spot.