The patient (male) has a hemizygous variant c.1204G>A p.(D402N) in KDM5C, a histone demethylase-encoding gene associated with Claes-Jensen syndrome (MRXSCJ) (OMIM: 300534), an X-linked recessive disorder.17 This evidence concerns the gene KDM5C and syndromic X-linked intellectual disability Claes-Jensen type.