Genotype-phenotype analysis of TCF4 mutations causing Pitt-Hopkins syndrome shows increased seizure activity with missense mutations.
OBJECTIVE
Pitt-Hopkins syndrome is characterized by severe mental retardation, characteristic dysmorphic features, and susceptibility to childhood-onset seizures and intermittent episodes of hyperventilation. This syndrome is caused by haploinsufficiency of TCF4, which encodes a basic helix-loop-helix transcription factor. Missense, nonsense, splice-site mutations, and gene deletions have been found in individuals with Pitt-Hopkins syndrome. Previous reports have suggested that the Pitt-Hopkins syndrome phenotype is independent of mutation or deletion type.


METHODS
We screened 13,186 individuals with microarray-based comparative genomic hybridization. We also conducted a review of the literature and statistical analysis of the phenotypic features for all individuals with confirmed mutations or deletions of TCF4.


RESULTS
We identified seven individuals with TCF4 deletions. All patients have features consistent with Pitt-Hopkins syndrome, although only three have breathing anomalies, and none has seizures. Our review of previously reported cases with TCF4 mutations and deletions showed that all patients with Pitt-Hopkins syndrome reported to date have severe psychomotor retardation, the onsets of seizures and hyperventilation episodes are limited to the first decade in most reported patients with Pitt-Hopkins syndrome, hyperventilation episodes are more common than seizures and are seen in the oldest patients, and individuals with missense TCF4 mutations are more likely to develop seizures.


CONCLUSIONS
On the basis of an analysis of published cases, we propose a genotype-phenotype correlation of increased seizure activity with missense TCF4 mutations.
Rosenfeld
Jill A
JA
Signature Genomic Laboratories, 2820 N. AstorStreet, Spokane, WA 99207, USA.
Leppig
Kathleen
K
Ballif
Blake C
BC
Thiese
Heidi
H
Erdie-Lalena
Christine
C
Bawle
Erwati
E
Sastry
Sujatha
S
Spence
J Edward
JE
Bandholz
Anne
A
Surti
Urvashi
U
Zonana
Jonathan
J
Keller
Kory
K
Meschino
Wendy
W
Bejjani
Bassem A
BA
Torchia
Beth S
BS
Shaffer
Lisa G
LG
D051778:Basic Helix-Loop-Helix Leucine Zipper Transcription Factors / Q000235:genetics*; D002648:Child; D005260:Female; D005838:Genotype; D006801:Humans; D008607:Intellectual Disability / Q000235:genetics* / Q000503:physiopathology*; D008297:Male; D020125:Mutation, Missense; D010641:Phenotype; D012640:Seizures / Q000235:genetics* / Q000503:physiopathology*; D017384:Sequence Deletion; D013577:Syndrome; D000073940:Transcription Factor 4; D014157:Transcription Factors / Q000235:genetics*
D051778:Basic Helix-Loop-Helix Leucine Zipper Transcription Factors; C532096:TCF4 protein, human; D000073940:Transcription Factor 4; D014157:Transcription Factors