Identification of ETFDH gene c. 487 + 2 T > A pathogenic variant and mechanisms for polycystic kidney in neonatal onset MADD.

Background: Multiple acyl-coenzyme A (CoA) dehydrogenase deficiency (MADD) is an autosomal recessive disorder resulting from mutations in the ETFDH gene. It is characterized by a wide spectrum of clinical symptoms, of which polycystic kidney disease is a specific phenotype of early-onset MADD. This study aims to broaden the genetic mutation spectrum of ETFDH gene. And we clarify the pathogenic mechanism of polycystic kidney caused by the loss of function of the ETFDH gene through in vitro experiments.

Results: Compound heterozygous variants in ETFDH (NM_004453: c.487 + 2 T > A, c.1395 T > G and c.1773-1774 del AT(in cis with c.1395 T > G) were identifed via trio-Whole Exome Sequencing (trio-WES) and confirmed pathogenic through Minigene Splice Assay and RT-PCR. This study, for the first time, demonstrated through both in vivo and in vitro experiments that c.487 + 2 T > A mutation lead to mRNA degradation through nonsense-mediated decay (NMD). Further cell experiments showed that downregulation of ETFDH gene led to lipid accumulation, enhanced oxidative stress, and upregulation of ZNF267 expression.

Conclusions: This study clarify the pathogenicity of c.487 + 2 T > A and c.1395 T > G mutations, aiding in the diagnosis and genetic counseling of ETFDH in clinical practice. The significance of this study is to reveal that ETFDH gene may be a key regulatory gene in the development of polycystic kidney.