Consistent with our findings showing that His96Arg mutation of BOLA3 impairs the maturation of [4Fe-4S]-NFU1, all the patients carrying the mutation displayed combined mitochondrial respiratory chain complexes deficiency, likely resulting in defects in the oxidative phosphorylation (OXPHOS) process. This evidence concerns the gene NFU1 and hyperinsulinemic hypoglycemia, familial, 4.