TBL1XR1 and infantile spasms: Moreover, a 5‐year‐old Japanese girl with West syndrome features was identified to have a de novo heterozygous c.209G‐A transition (c.209G‐A, NM_024665.4) in the TBL1XR1 gene, which results in a gly70‐to‐asp (G70D) substitution at a conserved residue in an F‐box‐like domain (Saitsu et al., 2014).