Mitochondrial Complex I Deficiency: Unraveling the Relevance of NDUFAF1 in Pediatric Hypertrophic Cardiomyopathy.

Hypertrophic cardiomyopathy (HCM) is rare in childhood, but it is associated with significant morbidity and mortality. Genetic causes of HCM are mostly related to sarcomeric genes abnormalities; however, syndromic, metabolic, and mitochondrial disorders play an important role in its etiopathogenesis in pediatric patients. We here describe a new case of apparently isolated HCM due to mitochondrial assembly factor gene NDUFAF1 biallelic variants (c.631C > T and an intragenic deletion encompassing exon 3, NM_016013.4). Alterations of this nuclear gene have been associated to Mitochondrial complex I deficiency, nuclear type 11 (OMIM *618234). We here report the fourth case of a child affected by complex I deficiency due to alterations in NDUFAF1 gene. His clinical features appear simpler when compared to the other cases described in the medical literature, increasing our knowledge regarding the highly heterogeneous clinical presentation associated with this disorder.