SMARCAL1 and Schimke immuno-osseous dysplasia: SIOD is caused by mutations in the gene encoding HepA-related protein (HARP) also known as SMARCAL1 [SWI/SNF-related, matrix associated, actin-dependent regulator of chromatin, subfamily a-like 1; Gene ID: 50485; NG_009771.1], a protein homologous to the sucrose non fermenting type 2 (SNF2) family of chromatin-remodeling proteins, required for transcriptional regulation, replication, repair, recombination, and covalent modification [7-11].