[Clinical analysis of a child with heterotopic ventricular gray matter Renpenning syndrome caused by PQBP1 gene mutation and a literature review].

Objective: To explore the genetic etiology of a child with Renpenning syndrome (RS), and review the literature on the clinical characteristics and gene mutations of RS.

Methods: A child with RS (patient 1) who was diagnosed and treated in the Pediatric Intensive Care Unit of the Third Affiliated Hospital of Zhengzhou University in November 2023 was selected as the research object. The medical history, family history, physical examination, cerebrospinal fluid examination, echocardiography, brain magnetic resonance imaging (MRI), brain magnetic resonance angiography, cardiac coronary CT angiography and intelligence quotient (IQ) score of child 1 were retrospectively collected. Peripheral venous blood samples were collected from patient 1, his parents, sister and brother, respectively. Genomic DNA was extracted from the child and his family members, and Trios-whole exome sequencing (Trios-WES) was performed. Sanger sequencing was used to verify the pedigree. Bioinformatics softwares (Mutation Taster, REVEL, SIFT, PolyPhen-2, GERP++, SWISS-MODEL) were applied. The pathogenicity of the detected variants was rated according to the American College of Medical Genetics and Genomics (ACMG) Standards and Guidelines for the Classification of Genetic Variants (hereinafter referred to as the ACMG Guidelines). "PQBP1 gene" "Renpenning syndrome" "PQBP1 gene" "Renpenning syndrome" were used as keywords in Chinese and English, respectively. Case reports of patients with RS caused by PQBP1 gene variants were retrieved from Wanfang Data Knowledge Service Platform, China National Knowledge Infrastructure and PubMed database. The clinical features and gene variants of RS caused by PQBP1 gene variants were summarized and analyzed. This study was reviewed by the Medical Ethics Committee of the Third Affiliated Hospital of Zhengzhou University (Approval No. 2024-334-01).

Results: The patient 1, a 12-year-old boy, was admitted to the hospital due to fever and disturbance of consciousness. Cerebrospinal fluid test showed viral encephalitis caused by human herpesvirus 7 infection. The main clinical manifestations were unusual facies (microcephaly, long narrow face, microphthalmos, superior oblique palpebral fissure, hypertelorism of inner canthus, bulbous nasal columella) and mental retardation. Auxiliary examination showed than patient 1 had atrial septal defect, nodular heterotopia in the posterior horn of the left ventricle, angiodysplasia, and low IQ. The disease began in infancy, and there was no family history of related diseases. A hemizygous deletion, c.459_462del (p.Arg153SerfsTer41), was identified in exon 5 of the PQBP1 gene in patient 1, which was inherited from his mother by Sanger sequencing. The results of bioinformatics analysis showed that the mutation was harmful. This variant was rated as pathogenic (PVS1+PS4+PM2_Supporting+PP3) according to ACMG Guidelines. According to the literature search strategy set in this study, a total of 13 cases of RS were retrieved, involving 16 cases of RS patient caused by PQBP1 gene mutation (patients 2-17), including patient 1, a total of 17 cases of RS. Among the 17 patients, 16 male patients had hemizygous mutations in the X chromosome PQBP1 gene, and 1 female patient had heterozygous mutations, including 12 deletion frameshift nonsense mutations, 3 point missense mutations, and 2 duplication mutations. Except for two fetuses, all patients had special facial features and low IQ to varying degrees. Ten patients had abnormal development of one or more organs such as eyes, heart, brain, etc. CONCLUSION: The main clinical manifestations of RS are developmental delay, long narrow face, bulbous nose, microcephaly, and may be accompanied by heterotopia of gray matter of ventricle and congenital heart disease. The c.459_462del (p.Arg153SerfsTer41) variant of the PQBP1 gene is the genetic basis of patient 1 in this study.