Heimler syndrome (HS [MIM: 234580]) is a rare autosomal-recessive disorder that was first described in 1991 in two siblings, born to healthy and non-consanguineous parents, with sensorineural hearing loss (SNHL), enamel hypoplasia of the secondary dentition, and nail abnormalities.1 Subsequently, five additional cases have been reported.2–4 In 2011, Lima et al.5 reported retinal pigmentation in one of the original individuals diagnosed with HS.1 The genetic cause of HS had not been identified, but it had been suggested that the syndrome could be due to mutations in a gene affecting derivatives of the ectodermal tissue, given that the described abnormalities have a common embryological origin.1 In contrast, because of the spectrum of clinical features, Lima et al.5 classified HS as a ciliopathy. In this study, we ascertained eight HS-affected families and analyzed them in a hypothesis-free way by whole-exome sequencing (WES). We identified biallelic PEX1 (MIM: 602136) or PEX6 (MIM: 601498) mutations in six of them. Further functional studies showed that HS is not a ciliopathy but rather a PBD with an atypical mild phenotype that shows limited clinical overlap with other PBDs.