[Genetic analysis of a rare case of Pitt-Hopkins syndrome due to partial deletion of TCF4 gene].

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.