Simultaneous identification of alpha-L-fucosidase and phosphoglucomutase (PGM) subtyping in semen stains.
Seminal fluid and stains were analyzed by isoelectric focusing to determine the donor phenotype in the alpha-L-fucosidase (AlFuc) polymorphic system. The enzyme is found in both seminal fluid and spermatazoa. Three common phenotypes exist and can be identified in fluid specimens stored at 4 degrees C for more than a year. Untreated semen specimens display more than eight distinct bands of alpha-L-fucosidase activity with isoelectric points of pH 6.6 and below. Neuraminidase-treated specimens have enhanced banding patterns cathodally with a loss of activity in anodal bands making it easier to phenotype specimens. Semen stains maintained in dehumidified chambers at 25 or 37 degrees C retained activity for at least one month and could be accurately phenotyped. Activity was observed in semen specimens maintained at -20 degrees C in the dried state for a period of one year, whereas a complete loss of activity was observed after two weeks in similar specimens maintained at 25 or 37 degrees C under humid conditions. Of seventy-four semen stains analyzed, two had no apparent activity. Of the remaining seventy-two specimens 56, 32, and 12% were phenotyped as FUC 1-1, FUC 2-1, and FUC 2-2, respectively. Calculated gene frequencies are FUC1 = 0.72 and FUC2 = 0.28. Following analysis of alpha-L-fucosidase, the agarose gel can be chemically developed to reveal the PGM1 subtyping pattern. The ability to phenotype both systems in semen stains significantly improves the ability of the analyst to individualize this type of physical evidence. The probability of discrimination for these two combined systems is approximately 0.89.