EFNB1 and Cowden syndrome 1: Additional genes have been identified in other less frequently observed syndromes where CS is a main symptom, including craniofrontonasal (EFNB1), Antley–Bixler (POR), Carpenter types 1 (RAB23) and 2 (MEGF8), and CS and dental anomalies (IL11RA) (Flück et al., 2004; Twigg et al., 2004; Jenkins et al., 2007; Nieminen et al., 2011; Twigg et al., 2012).