DNAJC19 is a mitochondrial inner membrane co-chaperone belonging to the Hsp40 family that regulates mitochondrial protein homeostasis 1. It functions as a component of the PAM (presequence translocase-associated motor) complex, facilitating ATP-dependent protein import into the mitochondrial matrix 1. DNAJC19 stimulates mitochondrial Hsp70 activity and works with prohibitins to regulate cardiolipin remodeling, essential for maintaining proper mitochondrial structure and cristae organization 2. Loss of DNAJC19 function causes dilated cardiomyopathy with ataxia (DCMA) syndrome, an autosomal recessive disorder characterized by early-onset cardiomyopathy, cerebellar atrophy, developmental delay, and 3-methylglutaconic aciduria 34. DNAJC19 mutations disrupt mitochondrial morphogenesis, leading to mitochondrial fragmentation and abnormal cristae formation 2. Patient-derived cardiomyocytes with truncating DNAJC19 mutations show increased mitochondrial respiration, elevated reactive oxygen species production, abnormal calcium kinetics, and reduced contractility 2. These metabolic and structural alterations directly impair cardiac function and contribute to the severe phenotype 5. DCMA represents a significant cause of childhood-onset cardiomyopathy requiring early genetic diagnosis and potential cardiac transplantation 5.