Pt827 was diagnosed with restrictive cardiomyopathy and complex I deficiency, and harbored the heterozygous de novo mutation c.575G>A (p.R192H, rs104894729) (S16 Fig) in TNNI3 (NM_000363); this exact mutation was reported to cause autosomal dominant familial restrictive cardiomyopathy (MIM 115210). Here, TNNI3 is linked to hyperinsulinemic hypoglycemia, familial, 4.