Individualization of fresh and stored human urine samples by PGM1- and Gc-subtyping

After 50- to 200-fold concentration by ultrafiltration, 56 fresh urine samples from healthy individuals (26 men, 30 women) and eight samples from corpses were subjected to isoelectrofocusing methods. All the urine samples tested could be correctly typed in both the phosphoglucomatase 1 (PGM1) and Gc system when compared to reference blood samples. The activity of urinary PGM1 revealed intraindividual and interindividual variations. To our knowledge this is the first report of PGM1 detection in urine. A systematic storage experiment over a period of 6 months was carried out at different temperatures (-20 degrees C, 4 degrees C, 20 degrees C); furthermore, aging of urine samples from 4 months to 4 years was investigated. The heterogeneous typing results were as follows. For Gc: after a storage period of 6 months positive results could be obtained in approximately 40% of those samples that were stored frozen (-20 degrees C) or in a refrigerator (4 degrees C). Some samples, however, showed negative analyses already after a 1 month storage period. At room temperature positive results could be achieved up to 3 months. Additional bands can appear in pherograms of urine samples stored at room temperature or in a refrigerator; they may cause misinterpretation, dependent on the original Gc-type. The maximum storage time compatible with successful Gc-typing was 1 year. For PGM1: this polymorphism could be regularly detected up to 1 week, and in some cases up to 1 month, in urine samples stored at 4 degrees C. The PGM1 activity gradually decreased; there were no additional or variant bands.