OBJECTIVE: To explore the genetic basis of a patient presenting with dysmorphism, intellectual disability, psychomotor delay and hypoplasia of corpus callosum by using next generation sequencing. METHODS: Genomic DNA was extracted from peripheral blood samples of the patient and his family members and subjected to exome sequencing. Suspected variants were verified with Sanger sequencing. RESULTS: The patient was found to carry a heterozygous c.1357delAinsGGA variant in exon 11 of the TCF4 gene, which was verified as de novo by Sanger sequencing. The variant may result in a truncated protein and affect its function. CONCLUSION The heterozygous c.1357delAinsGGA variant the TCF4 gene probably underlies the disease in the proband.
Facies ; Genetic Testing ; Humans ; Hyperventilation/genetics* ; Intellectual Disability/genetics* ; Male ; Transcription Factor 4/genetics*

Child ; Humans ; Facies ; Hyperventilation/genetics* ; Intellectual Disability/genetics* ; Mutation ; Transcription Factor 4/genetics*

OBJECTIVE: To explore the genetic etiology of a child featuring global developmental and mental retardation. METHODS: Chromosome G-banding karyotype analysis, copy number variation sequencing (CNV-seq) and high-resolution chromosome banding were used to screen the genomic variant in the child and his parents. RESULTS: Both the child and his father were found to have a karyotype of 46,XY,del(18)(q21.1q21.3), whilst his mother was 46,XX. CNV-seq analysis showed that the child was arr[19]18q21.2-q21.32(chr18:48 422 190-58 039 582)×1, with a 10.58 Mb deletion which encompassed the TCF4 gene. The same deletion was found in neither parent. High-resolution banding revealed that the father has a fragment of 18q21.1q21.3 inserted into 5p13.1. CONCLUSION The child was diagnosed with Pitt-Hopkins syndrome due to the 18q21.2q21.32 deletion. Chromosome karyotyping and CNV-seq can effectively identify submicroscopic chromosome anomalies.
Child ; Chromosome Banding ; Chromosome Deletion ; DNA Copy Number Variations ; Facies ; Humans ; Hyperventilation ; Intellectual Disability/genetics*

OBJECTIVE: To explore the genetic basis for a child featuring delayed intellectual development. METHODS: The child and his parents were subjected to conventional G-banding karyotyping and single nucleotide polymorphism array (SNP-array) analysis. Suspected copy number variations (CNVs) were verified in both parents. RESULTS: No karyotypic abnormality was found with the child and his parents. SNP-array results for both parents were normal. The child was found to harbor a de novo 172 kb deletion at 18q21.2 with a physical position of 52 957 042-53 129 237. The deletion only involved one OMIM gene, namely TCF4, resulting in removal of its exons 6 to 8. CONCLUSION The SNP-array assay has facilitated with the diagnosis of this child. Deletion of 18q21.2 region probably accounts for the Pitt-Hopkins syndrome (PTHS) in this patient.
Child ; Chromosome Deletion ; Chromosomes, Human, Pair 18 ; genetics ; DNA Copy Number Variations ; Developmental Disabilities ; genetics ; Facies ; Humans ; Hyperventilation ; genetics ; Intellectual Disability ; genetics ; Phenotype ; Transcription Factor 4 ; genetics

TCF4 (transcription factor 4; E2-2, ITF2) is a transcription factor that when haplo-insufficient causes Pitt-Hopkins Syndrome (PTHS), an autism-spectrum disorder that is associated with pervasive developmental delay and severe intellectual disability. The TCF4 gene is also a risk factor with highly significant linkage to schizophrenia, presumably via overexpression of the TCF4 gene product in the central nervous system. This review will present an overview of the clinical manifestations of PTHS and relate those clinical attributes to the underlying molecular genetics of TCF4. In order to provide a molecular biological context for the loss of function of TCF4 in PTHS, the review will also present a brief overview of the basic biochemistry of TCF4-mediated regulation of cellular and neuronal gene expression. In the final section of this review, I will discuss and speculate upon possible roles for the TCF4 transcription factor in neuronal function and comment upon how understanding these roles may give new insights into the molecular neurobiology of human cognition.
Animals ; Basic Helix-Loop-Helix Leucine Zipper Transcription Factors/genetics/*metabolism ; Disease Models, Animal ; Facies ; Humans ; Hyperventilation/diagnosis/*genetics/pathology ; Intellectual Disability/diagnosis/*genetics/pathology ; Neurons/metabolism/pathology ; *Transcription, Genetic