IFNGR1 and Schwartz-Jampel syndrome: Furthermore, SjS-susceptible mice expressing non-functional Ifnγ or IfnγR genes fail to develop any signs of a SjS-like disease (Perez et al., 2009; Kimoto et al., 2011), while mice expressing a non-functional IfnaR1 gene fail to develop the clinical disease (Cha et al., 2004).