The paleopathological study of the skeletal remains belonging to Cardinal Carlo de' Medici (1595-1666), son of Ferdinando I (1549-1609) and Cristina of Lorena (1565-1637), has been presented previously. A diagnosis of Klippel-Feil syndrome, tuberculosis and a polyarthopathy, interpreted as rheumatoid arthritis, was suggested. A revision of this case based on the analysis of the historical documents and of some radiological images of Carlo's bones has been proposed recently; according to the Authors, the Cardinal was affected by the 'Medici syndrome', a combined Psoriatic-DISH arthropathy. This revision offers us the opportunity to discuss this complex case, comparing different points of view, and to present the results of the molecular analyses carried out on Carlo's bone samples. We looked for the genetic risk factors of rheumatoid arthritis (RA) and psoriatic arthritis (PsA). We also searched for the primary candidate genes of RA and PsA, i.e. DR4 or DR1 and Cw6 or DR7 respectively, the latter predisposing also for psoriasis.
An original molecular protocol was applied to achieve an aDNA uncontaminated by exogenous sources and almost intact, starting from one of the Cardinal's rib pieces. The allele risk factors for both diseases were identified by PCR-SSP assay as HLA genotyping methodology.
Our data assigned Carlo the genotype DRB1*04/*11 for HLA-DRB locus and Cw*04/*12 for HLA-C locus.
Since Carlo was infected by M. tuberculosis during infancy and was carrying the DR4 variant but not the Cw6, he surely had a predisposition to RA, not to PsA and/or psoriasis. The diagnosis of RA is thus confirmed.