Family pedigree. Pedigree of the family members indicating the subjects carrying the C272T mutation of PRF1 gene at homozygous (closed circles) or at heterozygous (half circles) status. The proband is indicated by the arrow. The PRF1 sequence analysis revealed the presence of C272T (causing the A91V missense mutation) at the homozygous status in the proband and her fraternal twin and at the heterozygous status in the other family members. Furthermore, an additional G695A mutation (causing the R231H missense mutation) at the heterozygous status was found in the proband, in the healthy twin sister, and in the father.