RESUMEN
BACKGROUND: THOC1 mutation causes Deafness, autosomal dominant 86 [OMIM: 620280]. However, it has not been reported whether deletion of the THOC1 gene causes deafness. METHODS: Here, we report a 1-year-old girl with clinical features including Hypotonia, unilateral deafness in the right ear, and widening of lateral ventricles in 6 months. Gene mutations were identified by whole-exome sequencing. RESULTS: Through whole-exome sequencing, a deletion of 18p11.32-p11.21 contains the deletion of all THOC1 genes found in the patient but not in her parents' genomic DNA. The ClinGen Database Haplodose Insufficiency (HI) prediction tool determined that HI, THOC1 HI may cause unilateral deafness. Moreover, after 6 months of rehabilitation training, muscle tone returned to normal. However, at the age of 1 year, the patient developed symptoms of a large liver and hamartoma of both kidneys. CONCLUSION: From the above results, we propose that in our patient, THOC1 HI may cause unilateral deafness. Therefore, this study provides a new THOC1 deletion associated with unilateral deafness.