P–044 A non-classical splice site variant in ANOS1 gene leading to Kallmann syndrome

Abstract

Abstract Study question Genetic risk of the non-classical splice site variant in ANOS1 gene Summary answer A non-classical ANOS1 splice site variant, c.1062 + 4T>C, causes Kallmann syndrome. What is known already Genetic abnormalities play a key role in the development of Kallmann syndrome. Although an overwhelming majority of missense and nonsense mutations occur in the exons of a gene, intron mutations can also be pathogenic. Study design, size, duration The research object is a family. Eight patients of the family were recruited in this study, three of them were diagnosed with Kallmann syndrome. Participants/materials, setting, methods Genomic DNA was extracted from peripheral blood and whole-exome sequencing (WES) was performed to identify the genetic abnormalities. PCR was performed to verify the WES results. The functional splicing reporter mini gene assay was performed to assess the impact of sequence variants on splicing. Main results and the role of chance The proband and other two patients exhibited the typical clinical features of KS. A non-classical splice site variant, c.1062 + 4T>C in ANOS1 gene was identified, whereas the other unaffected family members did not have this mutation. This mutation caused the disappearance of the splicing site of intron 7 and the splicing position became the 156th base of exon 7, which caused a frame-shift mutation, leading to a premature termination of translation. Limitations, reasons for caution Since the ANOS1 gene is almost not expressed in the blood, in order to uncover the effect of this splice site variant of ANOS1, we carried out a functional splicing reporter mini gene assay in the mini gene vector pEGFP-N1. Wider implications of the findings: This study shows that mutations in non-classical splicing regions are also pathogenic. Therefore, it is recommended that the detection and analysis of this gene should pay attention to the non-classical splice site variant. Trial registration number Not applicable