Etfb, known as electron transfer flavoprotein β subunit, is involved in mitochondrial energy metabolism, specifically in mitochondrial β -oxidation and ATP production. It functions as an obligatory electron acceptor for several dehydrogenases in the mitochondrial matrix, and electrons it accepts are transferred to the main mitochondrial respiratory chain by way of ETF dehydrogenase (ETFDH) [4]. Disorders related to its deficiency can lead to glutaric acidemia type II, an inherited metabolic disorder [4].

In research, a novel homozygous c.143_145delAGG (p.Glu48del) mutation in the ETFB gene was found in a patient with glutaric aciduria type II, who presented with a neonatal-onset form with congenital anomalies and rapid development of cardiomegaly after birth [2]. Exome array analysis identified ETFB as a novel susceptibility gene for anthracycline-induced cardiotoxicity, with the missense variant rs79338777 (p.Pro52Leu; c.155C > T) increasing the risk of chronic cardiotoxicity [3]. In children with congenital hydronephrosis, the gene and protein expression levels of ETFB were upregulated, and there was a negative correlation with split renal function, suggesting it may be a novel marker for hydronephrosis [1].

In conclusion, Etfb is crucial for mitochondrial energy-related functions. Its mutations are associated with glutaric aciduria type II and anthracycline-induced cardiotoxicity, and its expression changes are related to congenital hydronephrosis. Understanding Etfb through research models helps in revealing the mechanisms of these disease conditions and may provide potential targets for treatment.