A novel splice acceptor site mutation of protein S gene in affected individuals with type I protein S deficiency: Allelic exclusion of the mutant gene

Sequencing studies of the protein S gene (PROS1) in a Japanese patient suff ering from recurrent thrombosis revealed the following. The proband and his first daughter, but not the second daughter, were having the type I protei n S (PS) deficiency due to a novel point mutation from A to G at the intron ic acceptor splice site in intron 13 of the PROS1. In the affected daughter , exclusion of the aberrant allele was assessed by the BstX1 dimorphism of PROS1 at Pro626 (CCG/CCA). The reduced PS activities in the proband and his first daughter were apparently due to defective production of mRNA from th e mutant allele. (C) 2001 Elsevier Science Ltd. All rights reserved.