A novel CHD7 mutation in a Chinese patient with CHARGE syndrome

• CHD7 is a member of the chromodomain family.
• CHD7 gene in a Chinese boy clinically diagnosed with CHARGE syndrome was sequenced.
• A new heterozygous, two-base deletion of CHD7 located in exon11 (c.2916_2917del) was identified.
• The truncated CHD7 (Q972X) only maintains the chromodomains but lacks all the other functional domains.
• This is the first CHRAGE syndrome in Chinese patients diagnosed by gene analysis.

In Genetics Out-patient Department of Shanghai Children's Medical Center, we consulted a 3-year-old boy with multiple anomaly syndrome (congenital heart disease, cryptorchidism, congenital deafness, mental retardation, exophthalmos, laryngeal cartilage dysplasia and high arched palate). We ruled out the possibility of multiple deformities caused by genomic imbalances. The patient was then clinically considered to have CHARGE syndrome, an autosomal dominant multi-system disorder involving defects in multiple organs, and CHD7 is the only known gene associated with the syndrome. Sequencing analysis of CHD7 of the proband identified a de novo heterogeneous mutation (c.2916_2917del, p.Gln972HisfsX22), a two-nucleotide deletion causing reading frame shift and resulting in a truncated CHD7 protein. Computational structure analysis suggests that the truncated protein only contains the chromodomains of CHD7, but lacks the SWI2/SNF2-like ATPase/helicase domain and the DNA binding domain, which are indispensable for the proper function of the protein, especially on chromatin remodeling. The patient then received follow up treatment in different clinical departments in a long period. To our best knowledge, this is the first CHARGE syndrome in Chinese patients diagnosed by gene analysis. In summary, the clinical symptoms and the description of treatment in the present case, combined with genetic test and functional prediction of CHD7, are helpful for further understanding and genetic counseling of the CHARGE syndrome.