[The gene-dose effect for peptidase A on the erythrocytes of a patient with Edwards' syndrome].

: The study of gene/dosage effect may be essential in tracing the pathogenetic steps which lead from an unbalanced chromosome anomaly to a pathological phenotype. We present a newborn with a clinical and pathological picture compatible with a diagnosis of Edwards' syndrome. Chromosome analysis on lymphocytes and fibroblasts confirmed the diagnosis showing the presence of trisomy 18. On chromosome 18 the enzyme peptidase A is mapped, and we demonstrated the gene/dosage effect for Pep A in the erythrocytes of our patient.