Houge type X-linked intellectual disability (CNKSR2 syndrome) is caused by either deletions or loss of function mutations in the CNKSR2 gene at Xp22.12.
The first reported patient had a 234kb deletion involving exons 15-21 of the gene.
Subsequently, a similarly affected patient with a 342kb deletion involving virtually the whole gene, but no other genes, was reported by Aypar et al.
A frameshift mutation within CNKSR2 was identified in a family by Vaags et al. and Damiano identified a truncating mutation in a further X-linked family.
These findings are consistent with the condition being due to loss of function of CNKSR2.