Summary
In a series of 16 propositi with symptomatic protein S deficiency and a protein S
gene mutation, we identified a sporadic case of a novel mutation that probably affects
gene expression. The mutation, a G to C transversion leading to the substitution of
Ala 484 by Pro, was not found in the protein S gene of the patient’s parents. Transmission
of the paternal and maternal protein S alleles was apparently normal, on the basis
of the frequent polymorphism in exon XV. We also checked the transmission of chromosomal
material by analysing protein C gene polymorphisms, Β-globin gene frameworks and four
variable number of tandem repeats (VNTRs). By combining the results of these analyses,
we were able to rule out nonpaternity and to confirm the de novo nature of the mutation.
