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Pitt-Hopkins Syndrome.
1Department of Medical Genetics, The Family Federation of Finland, Helsinki, Finland.
Molecular Syndromology
|June 7, 2012
Summary
Pitt-Hopkins syndrome (PTHS) is a genetic disorder caused by TCF4 gene haploinsufficiency. Diagnosis relies on clinical features and molecular confirmation of TCF4 gene abnormalities.
Area of Science:
- Genetics
- Molecular Biology
- Developmental Biology
Background:
- Pitt-Hopkins syndrome (PTHS) is a rare neurodevelopmental disorder.
- Characterized by severe intellectual disability, distinct facial features, breathing anomalies, and epilepsy.
- Congenital malformations are rare in PTHS patients.
Purpose of the Study:
- To summarize the current understanding of Pitt-Hopkins syndrome etiology and clinical presentation.
- To review the spectrum of TCF4 gene mutations associated with PTHS.
- To differentiate PTHS from similar genetic conditions.
Main Methods:
- Literature review of published cases of PTHS and TCF4 gene abnormalities.
- Analysis of mutation types, including deletions, frameshifts, nonsense, splice site, and missense mutations.
- Comparison of clinical phenotypes with identified genetic mutations.
Main Results:
- PTHS is caused by de novo haploinsufficiency of the TCF4 gene located at 18q21.2.
- Over 100 patients with TCF4 abnormalities have been reported, including those with 18q deletions.
- The mutational spectrum is diverse, with most mutations being private; no clear genotype-phenotype correlation exists.
- Pitt-Hopkins-like phenotypes are associated with CNTNAP2 and NRXN1 gene mutations.
Conclusions:
- TCF4 gene haploinsufficiency is the primary cause of Pitt-Hopkins syndrome.
- Molecular confirmation of TCF4 gene alterations is essential for PTHS diagnosis.
- Further research may elucidate genotype-phenotype correlations and expand diagnostic criteria.
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