[Analysis of clinical characteristics and genetic variant in a child with Nicolaides-Baraitser syndrome due to maternal mosaicism].

OBJECTIVE
To carry out genetic testing for a child featuring global developmental delay, abnormal liver function, congenital heart disease, and brain malformation.


METHODS
Peripheral blood samples of the child and his parents were collected for the extraction of genomic DNA and trio-whole exome sequencing. Candidate variant was verified by Sanger sequencing.


RESULTS
Genetic testing revealed that the child has harbored a heterozygous c.2002G>T (p.Glu668Ter) variant of the SMARCA2 gene, which was predicted to be likely pathogenic by bioinformatic analysis. His mother was found to be a low-percentage mosaic for the same variant, with a ratio of 0.054 (246/4549).


CONCLUSION
The child was diagnosed with Nicolaides-Baraitser syndrome resulting from maternal mosaicism for the SMARCA2 gene variant.