[Chitayat syndrome due to variant of ERF gene: A case report and literature review].

Objective: To explore the clinical features and management of a child with Chitayat syndrome.

Methods: A child presented at the Fengqing People's Hospital on August 8 2019 was selected as the study subject. Clinical data of the child were retrospectively analyzed. Peripheral blood samples were collected from the child and his father and sister. Whole-exome sequencing (WES) was carried out. Candidate variant was verified by Sanger sequencing. Genome Browser, AlphaFold, and PolyPhen-2 were employed for protein structure simulation and amino acid sequence conservation analysis. Pathogenicity of the variant was rated based on guidelines from the American College of Medical Genetics and Genomics (ACMG). Literature was retrieved from databases including CNKI, Wanfang, and PubMed using the keyword "Chitayat syndrome". The clinical characteristics and prognosis of patients with Chitayat syndrome were reviewed and analyzed. This study was approved by the Ethics Committee the Seventh Affiliated Hospital of Sun Yat-sen University (Ethics No.: KY-2024-086-01).

Results: The child was born at full term and had special facial features, skeletal abnormalities, recurrent respiratory tract infections and global developmental delay. WES and Sanger sequencing revealed that he has harbored a heterozygous c.266A>G p.(Tyr89Cys) variant of the ERF gene. Protein structure modeling suggested that the mutant protein has increased spatial distance between the side chain group and DNA, which may reduce its binding affinity to DNA. Amino acid sequence analysis indicated that the p.Tyr89 residue is highly conserved across multiple species. The variant was therefore classified as pathogenic (PM1+PM2_Supporting+PM6+PS1+PP3). The patient was diagnosed with "Chitayat syndrome". Nutritional support and rehabilitation training were recommended, though the child had died of severe pneumonia at 13 months old. Literature retrieval has collected 7 relevant articles, which involved 14 cases of Chitayat syndrome confirmed by genetic testing. Together with our case, all patients had facial dysmorphisms and skeletal deformities. Fourteen patients (93.3%) had respiratory distress. Seven of them (46.7%) had recurrent respiratory infections and 7 (46.7%) were confirmed with respiratory tract malacia. Eight (53.3%) patients had neuropsychological retardation, while 8 (53.3%) had growth delay. The main interventions for Chitayat syndrome include respiratory and nutritional support, and rehabilitation training for developmental delays.

Conclusion: Chitayat syndrome is rarely seen and its clinical manifestations may vary. Airway management and early intervention of developmental delay are important for improving the prognosis.