PCH1 often has prenatal characteristics of polyhydramnios with arthrogryposis multiplex congenita. Neonates with PCH1 present with hypotonia, impaired swallowing with consequent feeding difficulties and progressive microcephaly which mostly develops postnatally. Subsequently a severe psychomotor deficit becomes apparent. The clinical course is severe. About 40 patients with PCH1 have been reported. To date recessive mutations have been noted in the EXOSC3 gene and in single cases recessive mutations have been found in the tRNA splicing endonuclease homolog 54 (TSEN54), mitochondrial arginyl-transfer RNA synthetase (RARS2), and in the vaccinia-related kinase 1 (VRK1) gene. PCH1 has an autosomal recessive transmission.