SMARCAL1 and Schimke immuno-osseous dysplasia: SMARCAL1 is mutated in in a subset of Schimke’s Immunoosseous Dysplasia (SIOD) cases, and this mutation also abolishes SMARCAL1 fork reversal activity in vitro and triggers fork collapse and DNA damage in vivo, further supporting the notion that fork reversal is a protective mechanism 47, 49.