RNASEH2C c.194G>A is a Chinese-specific founder mutation in three unrelated patients with Aicardi-Goutières syndrome 3.

Biallelic pathogenic variants in RNASEH2C cause Aicardi-Goutières syndrome 3 (AGS3, MIM #610329), a rare early-onset encephalopathy characterized by intermittent unexplained fever, chilblains, irritability, progressive microcephaly, dystonia, spasticity, severe psychomotor retardation and abnormal brain imaging. Currently, approximately 50 individuals with AGS3 and 19 variants in RNASEH2C have been revealed. Here, we reported the novel clinical manifestations and genotypic information of three unrelated Chinese patients with AGS3 caused by pathogenic variants in RNASEH2C. In addition to three novel missense variants (c.101G>A, p.Cys34Tyr; c.401T>A, p.Leu134Gln and c.434G>T, p.Arg145Leu), one missense variant (c.194G>A, p.Gly65Asp) reoccurred in all patients but was completely absent in South Asian and other ethnicities. Our study expanded the variant spectrum of RNASEH2C and identified RNASEH2C c.194G>A as a Chinese-specific founder mutation. The novel phenotypes, including mouth ulcers, hip dysplasia, retarded dentition and hypogonadism, observed in our patients greatly enriched the clinical characteristics of AGS3.

[Clinical and genetic analysis of a novel CHD4 gene variant in a Chinese patient with Sifrim-Hitz-Weiss syndrome].

OBJECTIVE: To explore the genotype-phenotype correlation of a case with Sifrim-Hitz-Weiss syndrome (SIHIWES) caused by a novel CHD4 gene variant. METHODS: Genomic DNA was extracted from peripheral blood samples of the patient and her parents. Whole-exome sequencing (WES) was carried out for the patient.Suspected variant was verified by Sanger sequencing. RESULTS: The proband, a 2-year-old Chinese girl, presented with global developmental delay, intellectual disability, distinctive facial features and multiple congenital anomalies. Her prenatal manifestations included increased nuchal thickness, cranial and facial anomalies, and decreased fetal movement. WES has identified a novel variant in the CHD4 gene, namely NM_001273:c.2989C>G (p.Leu997Val) (GRCh37/hg19).Comparison of her phenotype with previously reported SIHIWES cases suggested that our patient's prenatal presentations were unreported before, with novel features including funduscopic anomaly, facial dysmorphisms such as asymmetrical ears, drooping eyelid, long philtrum and downturned mouth. CONCLUSION: Above findings have expanded the mutational spectrum of the CHD4 gene and revealed novel phenotypes in Chinese patients with SIHIWES.