Claes-Jensen Syndrome

KDM5C-associated XLID is also called Claes-Jensen syndrome. The clinical manifestations included severe ID, epileptic seizure, slowly progressive spastic paraplegia, short stature, microcephaly, maxillary hypoplasia, and small feet.14,15 The truncation or other types of variations of KDM5C have been found in patients with Claes-Jensen syndrome. The majority of missense variations functionally tested to date result in reduced demethylation activity of KDM5C.12,16 Here, we present 2 unrelated families with patients with XLID, harboring 2 novel KDMC variations, p.Q745E and p.E1131Afs.17 Phenotypes, clinical manifestations, and neurologic developmental courses of them were provided. In addition, the pathogenicity of these 2 novel variations was confirmed by in vitro functional assays.