Townes-Brocks syndrome caused by de novo mutation in spalt-like transcription factor 1 gene: a case report and literature review / 中华围产医学杂志

ABSTRACT

Objective:To summarize the clinical features and gene variations in children with Townes-Brocks syndrome (TBS).Methods:The clinical data of a female infant diagnosed with TBS caused by human spalt-like transcription factor 1 ( SALL1) gene mutation in Gansu Maternal and Child Health Hospital in May 2022 were analyzed retrospectively. Relevant articles up to July 2022 were retrieved from several databases including CNKI, VIP, Wanfang, Chinese Medical Journal Network and PubMed with the terms of " SALL1 gene" and "Townes-Brocks syndrome". Patients diagnosed with TBS caused by SALL1 gene mutation were retrieved and the clinical phenotype-genotype correlations in patients with TBS caused by frameshift mutation in SALL1 gene were analyzed and summarized. Descriptive statistical analysis was applied. Results:(1) Clinical data The index patient was a 40-day-old girl exhibiting major clinical manifestations of polycystic kidney dysplasia, congenital external ear deformity, preaxial polydactyly and recto-perineal fistula. Whole exome sequencing and Sanger sequencing revealed a heterozygous variation of c.420delC (p.S141fs*42) in the SALL1 gene, while the same gene was found to be wild type in her parents and sister. The variant was predicted to be pathogenic (PVS1+PS2+PM2). (2) Literature review retrieved 161 cases of TBS, of which 71 were attributable to a frameshift mutation in SALL1 gene. Clinical phenotypes of the 71 cases and the index case were summarized. TBS was mainly characterized by external ear, hand and anal deformities, sometimes accompanied by hearing loss, abnormal kidney development and foot deformity. A small number of affected cases presented with rare clinical phenotypes such as abnormal eyes, hypothyroidism and abnormal development. At present, the human gene mutation database records 110 variations in the SALL1 gene, with a majority located in exon 2. The most common mutation type was frameshift variation, accounting for 52%, followed by missense variation and nonsense variation. Conclusion:TBS should be considered in children with ear, hand and anal malformations, accompanied by renal dysfunction and hearing loss, and genetic testing is recommended for timely diagnosis.