The genetic cause of this disorder was described in 2007. This disorder is due to a haploinsufficiency of the transcription factor 4 (TCF4) gene which is located on the long arm of chromosome 18 (18q21.2) The mutational spectrum appears to be 40% point mutations, 30% small deletions/insertions and 30% deletions. All appear to be de novo mutations. The risk in siblings is low, but higher than the general population due to parental germline mosaicism. A<unk><unk><unk> -like phenotype has been assigned to autosomal recessive mutations of the contactin associated protein like 2 (CNTNAP2) gene on the long arm of chromosome 7 (7q33-q36) and the neurexin 1 alpha (NRXN1) gene on the short arm of chromosome 2 (2p16.3). Malformations in the CNS can be seen in about 60 to 70% of patients on MRI scans.<unk><unk><unk>  patients with a TCF4 deletion can lack the syndrome's characteristic facial features.
Pitt–Hopkins syndrome
Hypotrichosis–lymphedema–telangiectasia syndrome
Kasabach–Merritt syndrome
SUNCT syndrome
Rapp–Hodgkin syndrome
Schwartz–Matsuo syndrome
Franceschetti–Klein syndrome
Swyer–James syndrome