PCDH19 and infantile epileptic encephalopathy: Pathogenic COL2A1 variants have been associated with varying skeletal dysplasias, including achondrogenesis and hypochondrogenesis (OMIM 200610) [19], while pathogenic PCDH19 variants have been associated with a female-restricted form of sporadic infantile epileptic encephalopathy (OMIM 300088) [20].