PROTEIN-S MESSENGER-RNA IN PATIENTS WITH PROTEIN-S DEFICIENCY

A protein S gene polymorphism, detectable by restriction analysis (Bst XI) of amplified exonic sequences (exon 15), was studied in seven Ital ian families with protein S deficiency. In the 17 individuals heterozy gous for the polymorphism the study was extended to platelet mRNA thro ugh reverse transcription, amplification and densitometric analysis. m RNA produced by the putative defective protein S genes was absent in t hree families and reduced to a different extent (as expressed by alter ed allelic ratios) in four families. The allelic ratios helped to dist inguish total protein S deficiency (type I) from free protein S defici ency (type IIa) in families with equivocal phenotypes. This study indi cates that the study of platelet mRNA, in association with phenotypic analysis based upon protein S assays in plasma, helps to classify pati ents with protein S deficiency.