Diagnostic challenge of the newborn patients with heritable protein C deficiency

Objectivethe diagnosis of neonatal-onset protein c (pc) deficiency is challenging. this study aimed to establish the neonatal screening of heritable pc deficiency in japan.study designwe determined the changes in plasma activity levels of pc and protein s (ps) in healthy neonates, and studied newborn patients with proc mutation in the japanese registry.resultphysiological pc and ps levels increased with wide range. the pc/ps-activity ratios converged after birth. the pc/ps-activity ratios of 19 patients with biallelic mutations, but not, 9 with monoallelic mutation, were lower than those of 13 without mutation. the logistic regression analyses established a formula including two significant variables of pc activity (cut-off < 10%, odds ratio = 30.0) and pc/ps-activity ratio (cut-off < 0.35, odds ratio = 22.7), with 93% sensitivity and 44% specificity for determining patients with mutation(s).conclusionthe pc/ps-activity ratio is an effective parameter for the genetic screening of neonatal-onset pc-deficiency in japanese population.