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Updated: Jul 2, 2026

In Vivo Functional Study of Disease-associated Rare Human Variants Using Drosophila
Published on: August 20, 2019
Further delineation of Pitt-Hopkins syndrome: phenotypic and genotypic description of 16 novel patients
Background:
Haploinsufficiency of the gene encoding for transcription factor 4 (TCF4) was recently identified as the underlying cause of Pitt-Hopkins syndrome (PTHS), an underdiagnosed mental-retardation syndrome characterised by a distinct facial gestalt, breathing anomalies and severe mental retardation.
Methods:
TCF4 mutational analysis was performed in 117 patients with PTHS-like features.
Results:
In total, 16 novel mutations were identified. All of these proven patients were severely mentally retarded and showed a distinct facial gestalt. In addition, 56% had breathing anomalies, 56% had microcephaly, 38% had seizures and 44% had MRI anomalies.
Conclusion:
This study provides further evidence of the mutational and clinical spectrum of PTHS and confirms its important role in the differential diagnosis of severe mental retardation.
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