Molecular dynamics and minigene assay of new splicing variant c.4298-20T>A of COL4A5 gene that cause Alport syndrome

Frontiers in Genetics

Genetics

Lei Liang¹  Zeyu Cai²  Jianrong Zhao²  Haotian Wu³ 

[1] Center for Prenatal Diagnosis and Medical Genetics, Affiliated Hospital of Inner Mongolia Medical University, Hohhot, China;Department of Nephrology, Affiliated Hospital of Inner Mongolia Medical University, Hohhot, China;School of Public Health, Inner Mongolia Medical University, Hohhot, China;

关键词: alport syndrome;    COL4A5;    splicing variant;    minigene assay;    molecular dynamics;   

DOI  :  10.3389/fgene.2023.1059322

 received in 2022-10-01, accepted in 2023-02-13,  发布年份 2023

来源: Frontiers

【 摘 要 】

Introduction: Alport syndrome (AS; OMIM#308940) is a progressive hereditary kidney disease characterized by hearing loss and ocular abnormalities. According to the mode of inheritance, AS has three subtypes: X-linked (XL; OMIM#301050), autosomal recessive (AR; OMIM#203780), and autosomal dominant (AD; OMIM#104200). XLAS is caused by a pathogenic variant in COL4A5 (OMIM*303630) gene encoding type IV collagen (Col-IV) α5 chain, while ADAS and ARAS are consequences of a variant in COL4A3 (OMIM*120070) and COL4A4 (OMIM*120131) genes that encode Col-IV α3 and α4 chains, respectively. Usually, diagnosis of AS requires hereditary or pathological examinations. Splicing variants are hard to be determined as pathogenic or non-pathogenic based on the results of gene sequencing.Methods: This study focused on a splicing variant in COL4A5 gene, termed NM_000495.5: c.4298–20T>A, and to analyzed its authenticity and damaged α5 chain. In vitro minigene splicing assay was applied to investigate the effect of splicing variant, c.4298–20T>A, on COL4A5 mRNA synthesis. Molecular dynamics method was used to predict the capability of the responsible α5(IV) to form a triple helix.Results: The intron 46 of COL4A5 mRNA retained 18 bp, resulting in insertion of six amino acids behind the amino acid at position 1,433 of α5(IV). The predicted protein effect of this variant: p. (Pro1432_Gly1433insAspTyrPheValGluIle). As a consequence, the stability of α5(IV) secondary structure was impaired, probably leading to the unusual configuration of α345(IV).Discussion: Normally, splicing variant in COL4A5 gene can lead to phenotypes of XLAS, and the effect is associated with the extent of splicing. The patient reported here carried a c.4298–20T>A splicing variant in COL4A5 gene, and AS was highly suspected based on the pathology results. However, the patient did not manifest any ocular or ear abnormalities. We therefore present the c.4298–20T>A splicing variant in COL4A5 gene as likely-pathogenic splicing variant that leads to XLAS with mild phenotypes.

【 授权许可】

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Copyright © 2023 Liang, Wu, Cai and Zhao.