Germ-line PRKACG mutation. Electrophoregram of PRKACG gene (NM_00273), as sequenced by the Sanger method, revealed no mutation in individual II-3 designed as wild type (WT). Individuals III-1 and I-1 were found to be heterozygous (HE) for the c.222C>G mutation, without clinical features of macrothrombocytopenia. Patients II-1 and II-2 were found to be homozygous for the c.222C>G mutation and exhibited macrothrombocytopenia. The c.222C>G mutation caused substitution of the evolutionarily conserved Ile amino acid. Homologous sequences were aligned using the CLUSTALW Web site.